2018 Update Page covers all the new technology and
applications we covered in this newsletter in 2018. Now you
can review all that new tech at once.
Fiber FAQs Page (FAQ s = frequently asked questions)
gathers up questions readers have asked us (which first ran
in this newsletter) and adds tech topics of general
months "Good Questions" has some unique
questions including one about how fiber optic cable can
catch fire from the signals it carries!
By A VFL: Fibers
Damaged Placing Them In Splice Trays
a trend? Twice in one week, we have inquiries from readers
with problems and both were traced to fibers cracked when
inserted in splice trays. The photo below shows one of them
illuminated with a VFL. This was the same issue we found in
the first field trial of a VFL more than 30 years ago that led
to its popularity in field troubleshooting.
With High Fiber Count Cables - Share Your Experiences!
recently gotten several inquires about these new high fiber
count cables - 1728, 3456 or even 6,912 fibers. Like this
one from Prusmian with 1728 fibers:
We've been looking for directions on how to deal with high fiber
count cables. Several contractors tell us ribbon splicing is the
way to go, and most of these cables now use a version of the new
ribbon types that are flexible. We've found directions from Corning
on ultra high-density cabinets and put together this table
from some articles on splicing ribbons:
Is that realistic? We'd like more for a future story on these
cables, new ribbon types and how installers deal with them.
your experiences - email us at firstname.lastname@example.org.
how to prevent damage to pipelines and cables
CGA 811 Excavation Safety Conference & Expo is the premiere
international event dedicated to providing educational content
and resources to help protect buried assets. As the largest
event in the underground damage prevention industry, the
Conference draws nearly 1,700 participants and offers three full
days of educational content, including CEUs for select
To The New FOA Schools in Greece And Charlotte, NC
pleased to announce that School
of Telecoms in Aigaleo, Greece (FOA school 768) and OnePath
LLC in Charlotte, NC (FOA school 379) have joined the
FOA as an approved schools offering FOA certification.
The FOA Guide: Fiber Optics For Managers
the FOA, as part of the fiber optic industry and especially in
our role as educators, most of our focus has been training the
designers and installers of fiber optic cable plants and
networks. But what about the people for whom they work or
build the networks? What do network managers, project
network owners, IT personnel, facilities managers, network
designers, estimators, inspectors, etc. need to know about
fiber optics to ensure the success of their project?
The responsibility for the success or failure of any project
ultimately lies with the project manager. We've seen quite a
few instances of fiber optic project problems caused by
improper management and many of the help calls we get at FOA
indicate the manager's lack of knowledge of fiber optics. Some
of the problems they call us about are amazing. An IT manager
for a large metropolitan area found that the cable plant he
had installed didn't work because it had 4,000 bad connectors.
Another sent us OTDR traces submitted by his contractor for
documentation that showed only that the cables were too short
to test with an OTDR. In one big project, contractors
subcontracted to firms that had no fiber experience who were
digging up and breaking underground utilities daily.
These kinds of problems can be cured easily if the managers
have some basic knowledge of fiber optics and the processes
involved in building networks.. They do not need a typical FOA
fiber optic training course because those courses are based on
KSAs – the knowledge skills and abilities needed by installers
- and while they need to know what skills are necessary for
installers, they do not necessarily need those skills
themselves . What they need is just a basic understanding of
fiber optic network design, installation, testing and
has been working with several groups to develop educational
programs for managers. We've started with a page in the FOA
Guide on Fiber
Optic Network Management that describes what our
advisors think is important and created a page to introduce
them to the language and technology of fiber optics which we
Optic Jargon - Illustrated." Over time, we'll be
expanding this section and create a Fiber U self-study course
Want To Be A Guinea Pig And Save?
As part of our program to adhere to international standards for
certifying bodies and to ensure FOA certified techs are up to
date on the latest technologies and applications, FOA is also
considering adding a short online course based on our annual "Fiber
Update" as a future requirement for renewal. This course
would cover new technology and applications that FOA thinks all
technicians should be familiar with. Over the next year we will
be testing this concept by offering it to selected individuals.
You may be one of those selected! Watch your email for your
New Book On Tech (Warning: Shameless Self-promotion
from your editor - J
by the CIA? Talk on tapping fiber classified? The stories
As the author/editor of the FOA series of books, website and
this newsletter, I'm kept very busy. But late last year I
managed to finish my first book on high tech business called Delusional
Management. It's part learning management by analyzing
what others do wrong, part some history of the tech industry,
including fiber optics and part memoir of 50 years in high tech.
And some humor. Available
on Amazon in paperback and Kindle. Jim Hayes
Reading - News Summary
To Build Fiber Network in West Virginia -
Facebook, through their subsidiary Middle Mile Infrastructure,
is planning to build a high capacity fiber optic cable network
crossing a portion of West Virginia as part of the company’s
ongoing larger network infrastructure build stretching from
Virginia to Ohio.
Power Far north First Nation system - (from Bill
This Canadian project will bring electricity to 24 first Nation
reserves including the farthest ones north, Bearskin Lake and
Sachigo Lake. The towers will have OPGW and
ADSS for SCADA and other communications. all cables will
contain 96 fiber.
Joy of Standards - NYTimes - Life
is a lot easier when you can plug into any socket.
DOT Installing Fiber Along Roadway Near Colorado Springs
-(KKTV) - 17 miles buried along roadway for $2.5m - that's
$147,058/mile - ~$28/foot or ~$91.40/meter.
Optical LAN Expands Connection Choices - Two new
Optical Network Terminals targets high-density, and outdoor,
applications driven by Tellabs’ industry pioneering true
enterprise Passive Optical LAN software.
sues AT&T over ‘5G E’ marketing, calling it
deceptive and misleading.
Going On At Bell Labs: IP and Optical Networks.
We can approach the theoretical maximum information
transfer rates, as defined as the Shannon Limit,
discovered in 1948 by Claude Shannon, Bell Labs pioneer
and “father of information theory”.
Summer School On Subsea Fiber Optic Communications.
Best Practices for Utilizing GIS Data.
(White paper) American City
OPGW - Quick Reference Guide (AFL).
Contractors - Fiber Optic Knowledge Doesn't Always Trickle
Down (EC Mag)
Fiber: The Coming Tech Revolution―and Why America Might Miss
It by Susan Crawford, Yale
University Press, available
on Amazon. This is an extremely detailed history of how
several American communities have built FTTH networks that have
benefited their communities and incited incumbents to use every
legal means to squash most of them. (See link above about
municipal broadband being outlawed.) I should be required
reading for any city officials who contemplate building their
own FTTH networks. While it covers Chattanooga, TN, Wilson, NC
and Santa Monica, CA well, it does not go into the many DIY
groups that we've detailed here in the FOA newsletter like the
ANZA, CA electrical co-op or Southern Fiberworx or the hundreds
of smaller networks that have been built or are in the works.
Technologies Issues OTDR Test Report Summary
Pearson of Pearson
Technologies,, FOA Founder and Master Instructor announced
his latest publication, a two-part report titled Mastering
Singlemode OTDR Testing. In the first part,
Pearson tested a two-segment fiber link with OTDRs from
three manufacturers. The segment lengths were 103m and 6317m At
1310nm and 1550nm, Pearson Technologies compared repeatability,
accuracy and agreement of three characteristics. The
characteristics were length, connector loss, attenuation rate.
In the second part, with the same OTDRs used in the first part,
Pearson Technologies determined the minimum segment length,
above which singlemode attenuation rate measurements become
A summary of the results of the first part follows.
All three OTDRs exhibited excellent repeatability at both short
and long lengths and at both wavelengths. The largest difference
between repeated measurements, 0.08 m (3.14”), was so small that
field problems would be unlikely. In addition, comparisons of
length measurements made with different OTDRs at different times
should not result in incorrect interpretations.
Connector Loss Repeatability
All three OTDRs exhibited excellent connector loss repeatability
at both wavelengths. The largest average difference between
repeated measurements, 0.039 dB, was so small that field
problems would be unlikely. In addition, comparisons of
connector loss measurements made with different OTDRs at
different times should not result in incorrect interpretations.
Attenuation Rate Repeatability
At 6317m, all three OTDRs exhibited excellent attenuation rate
repeatability at both wavelengths. Maximum difference between
repeated measurements was less than 0.001 dB/km. In addition,
comparisons of attenuation rate measurements made with different
OTDRs at different times should not result in incorrect
At 103m, all three OTDRs exhibited poor attenuation rate
repeatability. Part 2 of the report presents Pearson
Technologies’ understanding of the cause of this poor
At both 103m and 6317m, all three OTDRs exhibited acceptable
length accuracy at both wavelengths. The largest difference
between software and manual measurements was 0.24m (9.8“). This
value is not considered likely to cause problems in locating a
defect or event.
Connector Loss Accuracy
After elimination of obvious errors, all three OTDRs exhibited
acceptable connection loss accuracy at both wavelengths. The
largest difference between software and manual measurements was
0.014 dB. This difference is small enough that it is unlikely to
result in errors of interpretation.
Attenuation Rate Accuracy
At 6317m, the attenuation rate accuracy was excellent at both
wavelengths. However, at 100m, accuracy was absent at both
wavelengths. The second part of this report presents an analysis
of the causes of such inaccuracy of singlemode attenuation rates
for short length segments.
Software Length Agreement
At both 103m and 6317m and at both wavelengths, all three OTDRs
exhibited acceptable agreement between manual and software
length measurements. Using any of the three OTDRs to find a
defect at either distance allows the installer to get close
enough to the location to find the problem.
Software Connector Loss Agreement
At both wavelengths, agreement of manual and software connection
loss was not as good as agreement between of other
characteristics. This reduced level of agreement may result in
difficulty of interpretation of loss increase if multiple
measurements are made with different OTDRs at different times.
Software Attenuation Rate Agreement
At both wavelengths and at 6317m, attenuation rate agreement was
good at 1310 nm and excellent at 1550 nm. However, at 100m and
at both wavelengths, attenuation rate agreement was poor and
unacceptable. These results indicate that all three OTDR were
unable to produce accurate attenuation rates measurements of
short singlemode segments.
While determining agreement between reflectance measurements
made on the three OTDRs was not an objective, the study
demonstrated obvious disagreement, indicated by low to high
differences of 21.9 dB at 1310nmand 13.6 dB at 1550nm. In
addition, all traces demonstrated violation of the
ANSI/EIA/TIA-455-8- 2000 requirement that the reflectance not
indicate detector saturation. Such saturation indicates the
reflectance values are lower/better than reality. As such, all
three OTDRs indicated inaccurate reflectance results.
Automatic Software Analysis Errors
The automatic trace analysis software of all three OTDRs
exhibited a significant incidence of errors. A consequence of
these errors is that the OTDR operator cannot blindly accept the
values in the event table. Some of these results will be
Parameters In Error
Based on more than 1,584 OTDR tests, Mastering Singlemode
OTDR Testing includes 92 pages, 13 figures, and 85
After May 6, 2019, the report will be available from Amazon.
Loss: Are You Positive It’s Positive?
post on a company’s
article on the CI&M website discussed the topic of the
polarity (meaning “+” or “-“ numbers) of measurements of optical
loss, claiming loss was a positive number. The implication was
that some people failed fourth grade math and did not understand
positive and negative numbers. The claim is that insertion loss
is always a positive number. Is that right?
Well the real problem is that to understand this you need to
understand logarithms and that’s Algebra II*, way beyond fourth
grade addition and subtraction. You see dB is defined as a
With logarithms, if the ratio of measured power to reference
power is greater than 1, e.g. measured power is more than
reference power, the log is positive. If the ratio of measured
power to reference power is less than 1, e.g. measured power is
more than reference power, the log is negative. If the ratio is
1, the log is 0.
Since the logarithm for optical power ratio is base 10 and then
multiplied by 10, each change of 10 in the ratio of the measured
and reference power becomes a change of 10dB. E.g. +10 dB is a
factor of 10 (10 times log10 10 which is 1), +20dB is a factor
of 100 (10 times log10 100 which is 2), +30dB a factor of
1000 (10 times log10 1000 which is 3)and so on. Negative
dB means division, so -10 dB means a factor of 1/10th (10
times log10 0.1 which is -1), -20dB a factor of 1/100th
(10 times log10 0.01 which is -2) and so on. 0 dB means the
measured power to reference power ratio is 1 – they are equal.
Let’s try a graphic explanation of this equation. Take a look at
this “semi-log” graph (logarithmic on the x axis and linear on
the y axis) of dBm vs optical power in the range commonly used
for fiber optics and calculated with our equation above.
Remember 0 dBm means all power is referenced to 1 milliwatt
As you move to the right, power increases and the value in dBm
gets more positive – that would be gain. So from 1mw to 10mw, we
see a gain from 0dBm to +10dBm or 10dB, a positive change.
As you move to the left, to lower optical power, as would be
loss, the dBm value gets more negative. From 1mw to
100microwatts (that’s 1/10mw), we go from 0dBm to -10dBm, or
-10dB; that negative change indicating a loss of 10dB.
That shows gain is positive dB and loss is negative dB. Now
we’re getting to the fourth grade math.*
How about an example? Let’s say we decide to test a singlemode
cable plant. We start with a laser source and launch cable which
we measure our reference level for loss with a power meter to
have an output of 0dBm. That’s 1 milliwatt of power, about the
normal output of a fiber optic laser. After we attach the cable
plant to test and a receive cable to our power meter, we measure
What power did we measure? The power must be lower, of course,
since we have loss, and 3dB is approximately a factor of 2, so
the power the meter measured is 1mw divided by 2 = 1/2milliwatt
or 0.5mw. Since our power meter is measuring in dBm, it will
read minus 3dBm (-3 dBm), since lower optical power is always
more negative. If it read +3dBm, the power measured would be 2mw
and that would be a gain from our reference (0dBm) which we know
is incorrect – passive cable plants are not fiber amplifiers.
Here is the graphical version of this loss test:
And then there is this short movie on the FOA
Guide page explaining dB showing how a power meter shows
loss when a cable is stressed to induce loss:
As the fiber is stressed, inducing loss, the power level goes
from -20.0 dBm to --22.3 dBm.That's a more negative number.
No question – loss means a more negative power reading in dB and
a negative number in dB indicates loss.**
But if you are a manufacturer of fiber optic test instruments
that offers optical power meters and sources to test loss, why
would this confuse you?
Perhaps we should blame accounting.
Suppose you have a company that has $1million in sales and
$900,000 in expenses. What’s the profit? It’s $1,000,000 -
$900,000 = $100,000. That’s a profit, right?
But suppose your company has $1million in sales and $1,100,000
in expenses. What’s the bottom line? It’s $1,000,000 -
$1,100,000 = - $100,000. Wait a minute, that is a negative
number – that’s not a profit, it’s a loss.
So in accounting, profits are positive numbers and losses are
negative numbers when we do the math, but when we talk about
loss, we don’t say we have a loss of “-$100,000,” we just have
we have a loss of $100,000. Then we’ll put that number in
parentheses when we publish our P&L like this ($100,000) and
hope it doesn’t get noticed by investors, but you know it will.
Loss and gain in fiber optic measurements are similar. If you
are using a separate source and power meter, loss will be a
negative number and gain will be a positive number. But because
of convention, we sometimes drop the signs when we report the
values because loss always means the optical power measurement
was negative and gain means the optical power measurement was
positive. But maybe that’s not what the convention has evolved
Optical loss test sets (OLTS) aren’t designed to measure and
display optical power, just loss. The actual power measured is
lost in the algorithms used for calculating loss based on the
“0dB” reference power and the measured loss. Long ago, most OLTS
measured loss and displayed it as a negative number, but some
companies who got into the fiber optic test equipment business
from other test businesses arbitrarily decided to display loss
as a positive number, and today most OLTS do show loss as a
positive number. But when the instrument sees a gain, which it
can do if improperly used, it therefore displays a negative
number, which can be very confusing to a trained fiber tech who
understands fiber optic power and loss measurements.
OTDRs do the same thing. I looked at traces from a half-dozen
OTDRs and all showed loss as a positive number and gain as a
negative number. And yes, when you have a gainer in one
direction, they show it as a negative number. Telling them that
is wrong will fall on deaf ears, I’m afraid.
The same article/blog post goes on to discuss optical return
loss and reflectance, which has similar issues but they get it
more or less right, which is confusing. Why can they understand
that more negative numbers for reflectance means lower power in
the reflectance but claim the opposite for insertion loss?
The “less right” is that with most OTDRs reflectance of an event
and optical return loss (ORL) are not the same thing. ORL is the
summation of all reflectance events and fiber backscatter from
the entire length of fiber.
And, please, please stop saying “back reflection;” a reflection
always goes back toward the source so the term is redundant and
was dropped from fiber optics years ago.
*So the problem is not simply fourth grade math, it also
involves a bit of convention and tradition and marketing. And it
requires understanding logarithms that create the negative
number of loss. That’s more like Algebra II or 7th grade math,
and here is a good tutorial from Kahn Academy on that: https://www.khanacademy.org/math/algebra2/exponential-and-logarithmic-functions/introduction-to-logarithms/v/logarithms
And more basic, here is a tutorial on adding and subtracting
negative numbers https://www.khanacademy.org/math/cc-seventh-grade-math
** If you want to calculate this yourself, FOA
has a XLS spreadsheet you can download that will calculate
the equations for optical power for you.
The FOA has an explanation
of dB on our online Guide and a couple of graphics that
illustrate what happens with loss.
Near Fiber Optic Cables
we ran a Q&A question about blasting near fiber optic
cables. Bill Graham, FOA Board Member and long-time instructor
in Canada, tells us that he suggests a more conservative
approach. This is what he has taught in his classes:
and Fiber Optic Cables
1.) Aerial on poles or towers
2.) Buried in ground
Blasting close to poles with fiber optic cables can depend
on the soil between the blasting area and the pole. For
example: In parts of Ontario there are large areas of
solid granite. The pole is generally bracketed to the rock.
(Some areas have started drilling the rock) there is a solid
connection from the blast hole to the pole, up the pole onto the
bracket and to the Fiber Optic cable, which they seem to forget
We recommend the following:
1.) Cover the aerial cable with Big O (4”
perforated drain pipe slit along the length) as shown in the
photo above. This protects only from flying rock.
2.) Removing the cable from the pole clamp and
hanging it from the bracket with a Bungie strap.
Blasting locations are carefully engineered… however, if the
crew wants to get home early on Friday and they double up on the
blasting the damage risk increases substantially. ( The red cups
in the photo are blast holes.) Most companies are wary
enough not to guarantee “no glass damage”. This area is almost
all solid granite.
Cables Buried Underground:
Regardless of Kinder Morgan’s recommendation, I suggest 5-6
meters separation is not adequate and should be at least
12 to 15 meters.
For Small, Private FTTH Systems
Trubey worked with his homeowners association to research and
develop a FTTH network. In doing this, he researched FTTH
thoroughly (including FOA). He's created a website to share
what he learned. FTTH.Build
is an informational site for HOAs and small communities
on how to build your own Fiber To The Home gigabit Internet
This web site is to help Home Owners Associations and other
small communities who are looking to build their own fiber
optic network to provision gigabit Internet for their
residents. It assumes that you are on your own, and no telecom
carrier is interested is building out a fiber network for your
area. Methods described here are applicable to communities
ranging in size from a couple of hundred residents to 20,000
or more residents.
Fiber Optic Tech Consortium Has New Website
FOTC, a group of TIA companies that promote fiber use, has a new
website with lots of information on the organization, it's
webinars and white papers. It also has a section on member news
that includes new products and applications.
to expand our certification offerings, adding "Fiber For
Wireless" last year, and fine-tuning our current
offerings to keep up with the changes in fiber optic technology
and applications. In the last year we've updated our CFOT, CPCT
and CFOS/O certification programs and their FOA references
online and in textbooks.
The CFOT fiber certification update includes adding more
information about new technology and products like SOCs
(splice-on connectors), microcables, as well as expanding the
information on OSP and premises applications. The CPCT premises
cable program has been updated to cover the new technology in
areas like passive OLANs and data centers.
The biggest change in FOA programs was to the CFOS/O Outside
Plant (OSP) Specialist program. We were asked to cover more
about OSP construction so we integrated the material from the
FOA OSP Construction Guide written by FOA Master Instructor Joe
Botha into the course. To make room for the new material, we
changed the prerequisites of the course to require a CFOT,
instead of covering basic fiber tech in the OSP course.
Certifications Now Last For 3-Years
in 2019, all FOA certifications issued or renewed will be for a
period of 3 years. Most certification bodies worldwide have
standardized on 3 year certifications. FOA has been working with
a number of organizations that use our programs but have
standardized on 3 year certifications. FOA has decided that it
is time to change our policies to align with the majority of
Remember that FOA certification renewals include all the
certifications one individual has for one price. FOA does not
charge for any additional certifications, so, for example, if a
CFOT also has specialist certifications like the CFOS/T or
CFOS/S, they are included at no additional cost when the basic
certification is renewed.
created a new section of the FOA
Guide on OSP
Construction. We've expanded some sections to
include more on cable pulling, blowing and aerial construction
with lashed and ADSS cables. The FOA has extensive material
available in our textbooks and online FOA Guide on what is
involved in the fiber installation process (cable installation,
preparation, splicing, termination and testing), so consider
this the textbook for the construction processes that occur
before the typical FOA CFOT-certified techs begin their work.
Included in this new Guide is comprehensive information on new
techniques like air-blown cables using microcables and
microducts. It also covers aerial cable installation more
thoroughly than is typically found in websites or literature.
The audience for this new section of the FOA Guide includes the
management of organizations owning or installing fiber optic
cable plants, designers or estimators of the cable plant, as
well as the actual CFOT certified techs doing the installation
work. It is intended to provide background information on the
entire project and in conjunction with the other FOA information
on basic fiber, OSP fiber, design and testing, provide complete
information on all stages of a fiber optic communications
FOA Guide to OSP Construction
Now that we
have the FOA Guide on OSP Construction, we can do a free Fiber U
online course on the subject. The new Fiber
U Course On OSP Construction includes a
review of fiber optic technology for those just getting started
or looking for an update, a lesson on project preparation, then
covers underground construction, underground cable installation,
aerial cable construction and installation, then leads you to
the next steps in OSP construction, splicing, termination and
This Fiber U course is aimed at managers of fiber optic
projects, either with the network owner or the contractor
building it, want to know how this construction is done and how
it needs to be designed, estimated and construction. It is also
appropriate for installers and contractors who are involved in
the construction process also.
Take the free Fiber
U Course On OSP Construction here.
As we researched products and installation practices for
the new OSP Construction sections, we came across some
interesting products and services. See
FiberNext Job Board And Savings Club For CFOTs
Approved School FiberNext
has created an online job board for fiber techs and a special
"savings club" for CFOTs.
Job Board was designed to help connect employers with fiber
technicians and other fiber optic professionals. It is a place
where employers in the fiber optic market can post job
openings and a place where fiber optic professionals can post
that they are looking for employment. Please feel free to post
an opening or browse for your next job or employee. https://fibernext.com/job_board.php
FiberNext, besides being an FOA approved school is also a
distributor. FiberNext invites FOA CFOT®s to join the “FiberNext
CFOT® Club to get special savings on selected fiber optic
products. Visit https://fibernext.com/cfot_club.php to
sign up today ”
Fiber Optic Cable
received this note from Steve Maginnis, LD4Recycle/ CommuniCom
Recycling on recycling fiber optic cable:
We have 3 Processors gearing up to accept fiber optic
cable (FOC). As we all know, all FOC is not the same. Several
truckloads of “typical” FOC scrap from FOC mfgrs and “typical”
FOC and Coax cable have been studied and tested.
Therefore, today you can begin contacting me with the type FOC
material or scrap you toss to the landfills today. We need to
quantify the expected feedstock. Our expectation for quantities
is quite large (tons) but there is a capacity limit. And I do
have several processors that can take ALL materials and others
that can accept LIMITED types of FOC material and quantity.
LD4Recycle/ CommuniCom Recycling
(Visit our new
On The Job
the most important part of any job. Installers need to
understand the safety issues to be safe. An excellent guide to
analyzing job hazards is from OSHA, the US Occupational Safety
and Health Administration. Here
is a link to their guide for job hazard analysis.
Eye Fiber Optic Work in Deadly Wisconsin Gas Explosion
killed, nine injured, and three buildings destroyed in
downtown Sun Prairie, Wis.
A hole punched into a 4-in.-dia gas pipeline during
fiber-optic line laying is blamed for an explosion that killed a
34-year-old fire captain and injured nine other people,
including four firefighters, in downtown Sun Prairie, Wis., on
July 10. The injured were treated at nearby hospitals and have
since been released. The blast destroyed three buildings,
including the Barr House, a tavern at 100 Main St. that was
owned by the deceased fire captain, Cory Barr.
Sun Prairie Fire Chief Chris Garrison said at a news conference
that after the leak was initially reported at 6:20 PM CDT, first
responders established a 300-ft-dia "hot zone" in the area and
evacuated about 65 people before the explosion occurred. "The
rapid response of firefighters, EMS and police saved a lot of
lives," Garrison said. "This could have been a lot more tragic
than it was."
The owner of the fiber-optics network is Verizon Wireless, which
confirmed in a statement that it had contracted with Bear
Communications "to provide a fiber backhaul for our networks."
It added that no Verizon employees were present at the job site.
"Verizon does contract with local providers in various markets
to provide fiber backhaul for our networks," the Verizon
statement said. "While we have not been contacted about the
investigation, both we and Bear are prepared to work with law
enforcement, public safety and public officials as they
investigate this tragic situation."
the story in ENR. And the final
report by the NTSB details the mistakes made by the
FOA also has lots of information on safety: FOA
video and a Safety
Practices Guide For Underground Construction
you are familiar with the "One Call" and "Call Before You Dig"
(811) program, but are you also familiar with the people behind
it - the Common Ground Alliance and their Best Practices
is a member-driven association of 1,700 individuals,
organizations and sponsors in every facet of the underground
utility industry. Established in 2000, CGA is committed to
saving lives and preventing damage to underground
infrastructure by promoting effective damage prevention
practices. CGA has established itself as the leading
organization in an effort to reduce damages to underground
facilities in North America through shared responsibility
among all stakeholders.
formed in 2000, the CGA represents a continuation of the
damage prevention efforts embodied by the Common
Sponsored by the U.S. Department of Transportation and
completed in 1999, this Study represents the collaborative
work of 160 industry professionals who identified best
practices relating to damage prevention. Any
best practice or program endorsed by the CGA comes with
consensus support from experts representing the following
stakeholder groups: Excavators, Locators, Road Builders,
Electric, Telecommunications, Oil, Gas Distribution, Gas
Transmission, Railroad, One Call, Public Works, Equipment
Manufacturing, State Regulators, Insurance, Emergency
Services and Engineering/Design.
the CGA Best Practices Guide here.
are all the CGA resources for damage prevention.
FOA is a
non-profit professional society whose members are all certified
techs - mostly CFOT®s
-Certified Fiber Optic Technicians - but also may be CPCTs -
Certified Premises Cabling Technicians or corporate
members involved in fiber optics.
FOA is a "virtual organization" - we have no "brick and mortar"
presence. We operate over the Internet with operations centered
in California, with active workers and volunteers in locations
as diverse as Texas, Ohio, Canada, Singapore, Malaysia, Denmark,
South Africa, the Middle East and many more.
Being a virtual organization, FOA has very low overhead,
allowing us to offer cost-effective certifications and many free
programs to support our industry.
As of today, FOA has certified this many techs. About 90% come
from our schools but many experienced techs have become FOA
CFOT-certified directly through our "Work-to-Cert"
FOA has almost 200 approved training organizations in about 40
countries around the world around the world.
FOA has 14
fiber optic certification programs covering every aspect
of fiber optic network design, installation and operation.
Certifications: CFOT (basic fiber), CPCT (premises cabling),
CFOS/O (outside plant, taught with CFOT included) and CFOS/D
(fiber optic network design).
Skills Certifications (for installers and techs, requires
CFOT): CFOS/S (splicing), CFOS/C (connectors/termination),
CFOS/T (testing), CFOS/FC (fiber characterization).
Applications Certifications (for techs or anyone, including
managers and supervisors): FTTH (fiber to the home), CFOS/L
(optical LANs), CFOS/DC (data centers), CFOS/A (fiber to the
antenna), CFOS/DAS (distributed antenna systems) and CFOS/W
(fiber for wireless)
(what you are reading)
FOA monitors the trade press, websites and other
resources continually to look at what's happening in many
technologies that affect fiber optics. We're tracing
technologies as diverse as wireless, IoT, autonomous vehicles,
smart cities, energy, or anywhere fiber is used to bring news to
FOA continually updates our technical materials, online and
printed, and our curriculum to ensure our readers have access to
the latest technical information and our schools teach the
latest technology and applications. Our printed books are being
updated right now.
FOA created the
FOA Online Guide as a non-commercial trustworthy technical
reference almost a decade ago so the industry would have a
reliable technical reference. In the last year, over 1million
visitors downloaded about 4 million pages of technical
FOA offers free online self-study programs at Fiber
U. In 2017, the number of online sessions doubled to
200,000. Many of those are preparing for FOA certification
programs - taking courses at our schools or using the "Work-to-Cert"
program. Some of our schools are requiring Fiber U programs as
prerequisites for their classroom courses so they can spend more
time on hands-on activities.
FOA offers over 100 educational YouTube
videos that have been viewed 2.4 million times.
FOA offers its training programs to other organizations at no
cost to help them train their members properly in fiber optics.
For example, FOA has been working with the Electrical Training
Alliance (IBEW/NECA) for over 20 years, training their
instructors for their apprenticeship programs. We work with many
other organizations and companies to provide the materials they
FOA has about 300 corporate
members - companies in various aspects of the fiber optic
industry worldwide that we list online and offer discounts on
certifications and renewals.
FOA provides speakers for many conferences and even
presentations for use by other organizations to educate people
on the aspects of fiber optic communications.
FOA has a program to provide classroom
materials for STEM
teachers (science, technology, engineering and math)
introducing K-12 students to fiber optics and creating science
FOA provides forums for discussion on various social media. Our
LinkedIn groups have about 5,000 members each. If you are not
joining us on social media yet, please do.
In A Career In Fiber Optics?
FOA has created a new YouTube video to introduce students to
careers in fiber optics. It was made for showing to high school
and junior high students interested in tech careers but anyone
interested in a possible career in this field will find it
interesting. If you have kids in school or know teachers, let
them know about this too. Watch the FOA
Careers In Fiber Optics Video on YouTube and visit the FOA
Careers In Fiber Optics web page at www.foa.org/careers/.
The word on
the "Dig Once" program is getting out - FOA is getting calls
from cities asking us for information and advice. It helps that
the current Administration is trying to convince cities of the
advantages of installing ducts or conduits when they dig up a
street so they don't have to do it again. Here are some links
for more information.
The DoT page on the administration’s Executive Order: http://www.fhwa.dot.gov/policy/otps/exeorder.cfm
From the Council of State governments: http://www.csg.org/pubs/capitolideas/enews/cs41_1.aspx
From the city of San Francisco: http://sfgov.org/dt/dig-once
An article about Dakota County, MN: https://muninetworks.org/tags/tags/dig-once
the one to download and hand out:
A “How To” Guide from The Global Connect Initiative: https://share.america.gov/wp-content/uploads/2016/04/6.-GCI-Dig-Once.pdf
have contacts give us online links for useful information which
we like to share with our readers. Here are two:
We Warn You To Be Careful About Fiber Shards
Photo courtesy Brian Brandstetter, Mississauga
Source Of Articles On Fiber
President and editor of this newsletter Jim Hayes has also been
writing a column in Electrical
Contractor Magazine for more than 15 years now. Electrical
contractors do lots of fiber work and this column has covered
some toics they are interested in including installation
processes, network design, fiber applications and in the last
year, a lengthy series on dark fiber - what it is, how's its
used and how it benefits the growth of communication. A recent
web site redesign makes it easier to browse all these articles -
just go to http://www.ecmag.com/contributing-authors/jim-hayes
and you can see all of them.
Optic Education For Students At Any Age
about fiber optics all the time - it's in the news whenever we
hear articles about high tech, the Internet and communications,
and many communities are getting "fiber to the home." But few
people really understand fiber optics or how it works. FOA is
focused on educating the workforce that installs and operates
these fiber optic networks but we're always getting inquiries
from STEM (science, technology, engineering and math) teachers
who want to introduce fiber optics to younger students in K-12
grades or technical schools.
start with the FOA
Careers In Fiber Optics Video on YouTube and visit the FOA
Careers In Fiber Optics web page at www.foa.org/careers/.
These are for students who think they might be interested in
careers in fiber optics and want to know more about what fiber
Using red laser light (a VFL here but a laser pointer works
also) to show how fiber guides light.
FOA has begun developing a series of YouTube videos intended for
teaching students in elementary, middle and high schools about
fiber optics. The first FOA video is titled "Fiber
Optics For Teachers." With this video, we show teachers
how fiber works and carries signals and then explains simple
experiments to demonstrate how fiber optics works in the
classroom using some plastic fiber and a laser pointer. Since
many teachers do not know where to get the fiber, the FOA offers
to send them a sample for use in demonstrations in their
classroom (USA only right now.)
At the end of the video, teachers are given directions on how to
request samples of the plastic fiber from the FOA.
This video joins the "Fiber Optics Live" series How
Light Travels In A Fiber, Fiber
Attenuation and Connector
Loss that show how fiber works using simple experiments
that can be duplicated in any classroom. More videos will be
If you have kids or know some teachers who would be interested,
please send them to the introductory video Fiber
Optics For Teachers and we'll be glad to help them
get started with some entertaining programs for their
For Teachers In K-12 And Technical Schools
Teachers in all grades can introduce their students to fiber
optic technology with some simple demonstrations. FOA has
created a page for STEM or STEAM (science, technology,
and math) teachers with materials appropriate to their
classes. Fiber Optic
Resources For Teachers.
you have kids in school or know teachers who are interested,
send them to the FOA page Fiber
Optic Resources For Teachers.
Your Company Become An FOA Corporate Member?
As all FOA
members know, they join the FOA by becoming certified,
mostly taking their CFOTs but some CPCTs, either by
attending a FOA approved school or joining directly based on
field experience (our "work to cert" program.) Over the years,
we've been contacted by manufacturers, contractors, consultants,
and other types of organizations who ask about becoming members.
We don't certify companies or organizations, we told them, so we
were not sure what we could offer as a benefit of membership.
But then, companies asked about using our educational programs
to train employees, how they could get listed on the FOA website
as service providers or if they could get a quantity discount on
membership or certification for all the FOA members working for
them. That began to sound like a benefit for being an FOA
corporate member. And providing a list of useful suppliers to
the market could be a benefit to the industry as a whole.
So FOA has quietly been letting companies and other
organizations join the FOA to take advantage of those benefits
so we now have several hundred corporate members. We've put then
into a database and listed them on the FOA website in map
form. Here's the map.
The online map
can be used to find suppliers and service providers.
The map, like our map of schools, lets you find the FOA
corporate members close to you. The table form lists them
by category: Installer/Contractor, Component Manufacturer,
Installation Equip. Manufacturer, Transmission Equipment,
Services/Consulting, Distribution and Users of Fiber Optic
Networks. You can sort the tables to find members meeting your
needs, e.g. by location, certifications offered, etc. Click on
any column heading to sort that column; click twice to sort in
Does An Organization Become An FOA Corporate Member?
just fill in the online
application form. When your application is accepted, you
will be asked to pay the one time membership fee - $100US. You
will then be listed on the online
have access to exclusive FOA educational materials for your
employees and get discounts on certifications and
now posts events on our LinkedIn groups, Facebook page and
other social media
has a company page and three LinkedIn Groups
- official company page on LinkedIn
- covers FOA, technology and jobs in the fiber optic marketplace
Fiber Optic Training - open to all, covers fiber optic
technology and training topics
de La Asociación de Fibra Óptica FOA (Español)
FOA offers free standards for datalinks and testing the
installed fiber optic cable plant, patchcords and cable, optical
power from transmitters or at receivers and OTDR testing. Look
for the "1
PageStandard" web page and in the FOA Online Reference
301 Fiber Optic Installation Standard
cover components and systems and how to test them, but rarely
get into installation issues. The FOA NECA 301 standard which
covers installation of optical fiber systems has been revised
for the second time, adding considerable new materials. This
standard is derived from FOA educational material put in
standards form and approved by ANSI as an American National
Standard. It's specifically written to be used in contracts to
define "installation in a neat and workmanlike manner." The
standard is available from NECA.
FOA members can go
here for instructions on how to download your free copy.
Fiber U Self-Study Programs
"Fiber U" free online self-study programs help you learn about
fiber optics, study for FOA certifications or use them to help
create "blended learning" classes. There are two new free online
self-study programs on Fiber
U. Fiber Optic Network Design is for those interested in
learning more about how to design fiber optic networks or
studying for the CFOS/D certification. FTTx is for those wanting
to know more about fiber to the "x" - curb, home, wireless, etc.
- or studying for the CFOS/H certification.
Got to Fiber U
for more information.
Online Self-Study Programs Offer Certificates of Completion
been offering quite a few free online self-study programs on Fiber
U, our online learning site. We are always getting
questions about getting a certificate for completing the course
online, so we have setup an option to take a test online and get
a certificate of completion for these online courses.
While it's not FOA certification, FOA will recognize a Fiber
U Certificate of Completion as background experience to
qualify for applying for FOA certifications. We also intend to
expand the program to more specialized topics as preparation
for FOA specialist certifications.
If you have associates that want to get started in fiber,
have them take this course online to get started. Go to Fiber
U and get started.
Books And Publications
Many textbooks are behind the technology because they are
rarely updated. FOA really keeps our textbooks up to date. We
did a major update a year ago and another was just completed.
The The FOA
Reference Guide To Fiber Optics has been updated
to reflect new components like OM5 fiber, testing for fiber
characterization and more information on installation.
Reference Guide To Outside Plant FIber Optics
has been expanded to include an extensive section on outside
plant construction taken from Joe Botha's
OSP Construction Guide textbook. This additional
material is being added to support the new FOA CFOS/O OSP
tech certification program which now includes of OSP
Basic Fiber Optic Textbook Available in French and Spanish
de Diseño para Redes de Fibra Óptica en
Español - FOA
Design Book Available In Spanish Online
FOA has translated the FOA Guide To Fiber
Optic Network Design book and made it available online to
those studying for the CFOS/D Certification but whose native
language is Spanish. You
can access the Spanish translation of the Design book here.
A printed version will be available in the near future.
& Uncle Ted Guides - Perfect For Getting Started
Ted's Guides have moved to the FOA website.
Lennie is the place where many if not most fiber techs
begin their education. FOA has just updated the two
guides to ensure they stay relevant - more than 20 years
after they were first written.
Lennie goes all the way back to 1993 when he was created
as the mascot of the original "Fiber U" conference - the
same Fiber U that is now the FOA's web-based training
Lightwave's Guide To Fiber Optics was created
as a beginner's introduction to fiber optics. Over
60,000 printed version of Lennie's Guide were given away
and it became one of the first commercial web pages in
1994. Uncle Ted's
Guide To Communications Cabling was written a
few years later to introduce techs to "Cat 5" - UTP
wiring - that had only recently been standardized in
Lennie and Ted's Guides are used in the current Fiber U
online self-study programs and are still the best place
to start learning about fiber optics.
Ted's Guides are online at the links here, can be
downloaded as printable PDFs and are now also available
as free iBooks on iTunes.
Lightwave's Guide to Fiber Optics and
Ted's Guide To Communications Cabling
are now available free to iPad users who can download them from
the Apple iTunes store. Of course they are still available
online or for download.
You can also find these free guides on the FOA website - go here
for all the links: Lennie
Lightwave's Guide to Fiber Optics and Uncle
Ted's Guide To Communications Cabling
Download PDFs of Lennie
or Uncle Ted.
LossCalc estimates the optical loss of a fiber optic link. This
will save time for the installer of a fiber optic link needing
to know whether test results are reasonable and/or make a
"pass/fail" determination. It can also help the designer of a
link to determine if communications equipment will operate over
By choosing the type of link (singlemode or multimode) and
specifying the length of the fiber and numbers of connections
and splices, it will calculate the end to end loss of the link.
The app has default specifications for singlemode and multimode
links or the user may create custom setups with specifications
appropriate for any application. http://itunes.apple.com/us/app/foa-losscalc/id476262894?mt=8&ls=1
Self -Study in Fiber Optics
first app is a self-study version of the FOA Reference Guide to
Fiber Optics. The FOA APP builds on the FOA basic fiber optic
textbook to create an interactive learning environment that
builds on the iBook electronic version of the book to add a
guide to use for self-study and real-time testing that provides
feedback on what you have learned and correct answers to
questions answered incorrectly.
The FOA APP is priced at only $9.99, same as the iBook, so the
self-study program is free. Download it from the Apple APP Store
with your iPad or iTunes.
FOA has many videos on ,
including two Lecture Series (Fiber Optics and Premises
Cabling), Hands-On lectures on both and some other informational
and instructional videos. For all the videos, go
to the FOA Channel "thefoainc" or use the direct links
a complete list of FOA Videos with links to each video on
The Jobs In Fiber Optics? FOA talks about all the
applications for fiber optics, what jobs involve and the
qualifications for the workers in the field.
Optics - Live! A
series of videos that use lab demonstrations to show how
optical fiber works.
Project Management - what's involved in a
copper/fiber/wireless project -advice for the customer and the
Of Counterfeit Cable
have read the stories we have written about the counterfeit
"Cat 5" cable made from copper-clad aluminum rather than pure
copper. Recently we tried an unscientific burn test on the
cable compared to a known good UL tested cable and posted a
video on YouTube. You can see the results below.
Cable Real UL-rated cable
difference is obvious and the danger is real. Watch the video
on YouTube: Premises
Cabling Lecture 11: Counterfeit Cat 5 Cabling
complete list of FOA Videos with links to each video on
all the FOA Channel on YouTube.
New in the FOA Online Fiber Optic Reference Guide?
continually updating the Online Reference Guide to keep up with
changes in the industry and adding lots of new pages of
technical information. Go to the FOA
Guide Table of Contents to see the latest updates - look
FOA Newsletter, Online Guide and website with DuckDuckGo.
FOA Online Fiber Optic Reference Guide.
Communications Technologies, FOA
Approved School #378.
a listing of all the FOA-Approved schools here.
Find An FOA-Approved Training
inquiries we get regarding finding a FOA-Approved training
organization want to know two things: what school is closest to
me or what school offers the certifications I need. The FOA has
about 200 training organizations we have approved worldwide so
finding the right one can be difficult! We've been looking at
ways to make it easier, and we think we've got a good solution.
In fact we have two solutions.
First we have added a sortable
table of all the FOA-Approved schools.
You can also use our FOA
Google Map to find FOA-Approved schools.
Should A Fiber Optics or Cabling Tech Know and What Skills Do
certifications are based on our KSAs - the Knowledge, Skills and
Abilities that techs need to succeed. Read the FOA KSAs
for fiber and cabling techs.
enjoy feedback, especially when it shows how great some FOA
instructors are. These came from students of Tom Rauch, an
instructor at BDI
"I took your fiber optics certification courses this past March.
I just wanted to let you know that in two weeks I start working
as a fiber optic technician with ___ up in ___. You mentioned on
the first day of the course that there is always one guy in
class who had rubbed his last two nickels together to be there
and, in that instance, I was that guy. Now I'm going to be able
to provide for my family like never before and I owe it to the
certification that I received from you and BDI Datalynk. I just
wanted to thank you again."
"Thanks to our tremendously knowledgeable and patient instructor
Thomas Rauch, who was not only generous in sharing his wealth of
information, but he did so with ease, humor and in a way that
invited curiosity and participation. He was encouraging and
proud of our accomplishments and helped us learn from our
mistakes in a way that did not break our confidence, rather it
pushed us to better results the next go around. The hands on
labs were just AWESOME!" Just thought you should know what a
class act you have representing you in his travels..... but then
again you probably already knew that! : )
In almost 19 years at Verizon and having held numerous
positions, I have gone through many training sessions. I cannot
remember ever having been actually looking forward to coming
back to class quickly after lunch, to get back to the hands on
activities, and walking away with the sense of empowerment that
the information presented was not only relevant but dead on
point accurate! I will be signing up for the Outside Plant class
on March! I can't say enough good things about Tom and his
impact! Feel free to quote me, I can only imagine that he will
open so many doors and change so many lives in the years to
come, with his style of teaching! Great experience, awesome job!"
and FOA Partner on Fiber Optic Training
International Brotherhood of Electrical Workers (IBEW) and the
National Electrical Contractors Association(NECA) through the
National Joint Apprenticeship and Training Committee
a partnership with the FOA has published a new textbook for
training IBEW apprentices and journeymen in fiber optics. The
new textbook uses the material from the FOA Reference Guide To
Fiber Optics with new material and photos from other NJATC
from one of our certified instructors: I want to thank
you and your organization for all the resources you provide for
the students and the opportunity to offer the certification to
the students. The fact that you published the book yourself to
get the cost down and the unlimited free resources on your
website shows a commitment to the public that is second to none.
I let it be known to the students that the FOA is the best in
the industry at supplying knowledge and resources related to the
communication industry. I look forward to passing on the
information that you provide for the industry.
Question! Tech Questions/Comments Worth Repeating
The FOA Fiber FAQs
Page (FAQ s = frequently asked questions) gathers up
questions readers have asked us and adds tech topics of
Questions From FOA Newsletter Readers
Test Multimode At 1310nm
Q: Can I test multimode over 1310 wavelength?
A: Certainly you can, but why? In fact, multimode fiber
has been tested at both 850 nm and 1300 nm for most of its
history. Some standards still call for testing at both
When network speeds were 100Mb/s or less, sources were LEDs at
850nm used for shorter links - a few hundred meters - and LEDs
at 1300nm were used for longer wavelengths, up to 2km for
networks like Ethernet, FDDI and ESCON.
When Ethernet jumped to 1 gigabit/s, LEDs could not be used;
they were limited to ~200 Mb/s. The new fast VCSEL sources
(vertical cavity surface-emitting lasers) were adopted for most
links. Some networks still offered a 1300 nm option using 1310
nm Fabry-Perot lasers since VCSELs are limited to about 950nm
wavelength max. The 1310 lasers available were generally
pigtailed with singlemode fiber and required some special launch
cables to prevent modal problems, and even though they offered
longer range, they were not really cheaper than using singlemode
fiber and never gained much popularity. (See Specifications for
fiber optic links and systems, including FTTx)
So multimode fiber became almost exclusively used at 850nm. In
standards committees we discussed dropping the requirement for
testing at 1300nm, but some argued that since the fiber is more
sensitive to stress/bending losses at 1300nm, testing at 1300nm
provided information on the stress in the fiber. Once multimode
fiber became almost exclusively bend-insensitive fiber, that
argument lost validity.
While some standards still call for 1300nm testing and many test
sets offer 850nm and 1300nm LED sources, it’s probably not worth
Fiber Backscatter Coefficient
I was wondering if you have an idea of how accurate the numbers
from a fiber datasheet are for the stated backscatter
coefficient of the fiber. When looking at these numbers
reported on datasheets, they are nice round numbers like -77dB,
-82dB etc., which tells me that those aren’t actual
measurements. They are more ballpark values. Would
you happen to know roughly what sort of accuracy those would
have for a given length of fiber?
A: We believe is the number is an average from some tests
done whenever the fiber was designed and first manufactured and
is +/- several dB. Remember it’s not a guaranteed spec like
attenuation coefficient which they do measure.
Remember it is dependent on the pulse width. Corning in the
SMF-28 data sheet quotes the numbers you have for a 1ns pulse
You can probably surmise that 1 ns pulse is hardly a square wave
and there will be lots of variations in the integrated power in
a 1ns pulse created by different instruments. And who knows how
you relate that power to a 5, 10, 20 ns or whatever pulse.
This paper by Corning talks about reflectance and backscatter
and has some interesting points:
The key is backscatter is inversely proportional to mode field
diameter, so small changes in fiber diameter can cause changes
in backscatter - and MFD variations of several percent are
Q: For overhead installation, can snow shoes, or other
service loop devices, hold two separate cables? I imagine
the bend radius is a factor.
A: Snowshoes come in many sizes and are often sized for
holding several cables, for example loops around dome splice
closures with 2 cables being spliced.
Q: If I
have 50 micron test leads for my OLTS and I used them to test a
62.5 micron fiber link what can I expect in terms of
results? Will the 50 micron leads give me (generally)
higher or lower loss values?
A: Yes, you will see higher and or lower loss depending on which
way you test. See this
page in the FOA Guide on Mismatched Fibers.
Pull ADSS Cable In Ducts Underground?
Q: Our city is installing a 1.5 mile run, mostly aerial
and we want to use ADSS cable. There are two or three road
crossings where we want to go underground in conduit installed
by directional boring. Can the ADSS cable be dead-ended, brought
to the ground, figure-8ed and pulled through conduit then
continue the aerial installation?
A: The answer is yes this is not an issue and is done all
the time. It is standard procedure. (Thanks to Pat Dobbins, FOA,
the expert on ADSS cables.)
Q: I recently read an article you wrote in April of last
year about micro trenching..Currently, I am employed with an
underground construction company. Something we have never been
involved with is micro trenching and would like to possibly get
some equipment and training scheduled in the near future. In
saying that, it has seemed to be almost impossible to find
numbers on the price per foot. Essentially, I am asking if you
have any resources to some up with those numbers or models to
maybe use for pricing purposes.
A: Microtrenching is becoming another tool that
contractors are adopting because like directional boring is is
less disruptive than regular underground construction. I’m
working with one group that’s using microtrenching in CA cities,
installing microducts and a 288 fiber about the size
of a #2 pencil. Cost is difficult to generalize other than “more
than aerial and less than trenching.” Cost is very dependent
on where you are working and what the local geography
looks like. We know one contractor who claimed to do 5 miles a
day in rural Washington at costs near that of aerial. It’s
especially good in areas with lots of base stone where trenching
or boring is near impossible or cluttered utilities downtown.
Here are a couple of pages on the FOA website about
Plant Fiber Optic Cable Plant Construction
Ditch Witch sells equipment for trenching and trains users.
Condux has the equipment for blown cable and offers training
several times a year.
Old Multimode Fiber
Q: We have old multimode fiber and we are still connecting
more equipment to it over greater distances and need some way to
insure the equipment will work.
A: I do not know of any simple formula for figuring this
out. Last time I remember such a formula from around 2000 done
for Gigabit Ethernet with VCSELs and the equation reminded me of
the quantum mechanics course I took in physics. The problem is
you have two bandwidth factors, modal dispersion and chromatic
dispersion. Modal dispersion is highly dependent on mode fill,
e.g. the metric “encircled flux” was developed to define the
mode fill of multimode fiber with VCSEL sources for simulations
to estimate bandwidth. Chromatic dispersion is dependent on the
fiber spec and the spectral width of the source which is better
with lasers and LEDs.
What generally happens is the standards group developing the
network standard, especially IEEE 802.3 for Ethernet, runs the
numbers and specifies a maximum distance for the particular
network and its speed. FOA has a table of these specs here: Specifications
for fiber optic links and systems, including FTTx
Can A Fiber Optic Cable
Q: While working on a cut-over of a dwdm circuit
something has happened that I am now looking for an explanation.
A transmission fiber emitted "fire" on that same fiber! We did
not see any optical light we saw fire. About 5 cm of fiber
burned and remained smoke. What phenomenon occurred? Are the
dwdm amplifiers so powerful enough to generate fire?
Unfortunately I could not get into the station to take the model
of the equipment.
A: We’ve heard of high power WDM systems exploding dirt
of the endface of fiber connectors and damaging them, but this
is a new one. We contacted several technical people in fiber
companies and found that this can happen if there was a crack in
the fiber in the cable near the connector or lots of reflection
perhaps caused by a very dirty connector that allowed the very
high power to heat the cable enough for combustion. DWDM with
many multiplexed signals and a fiber amplifier creates a lot of
power confined to a very small core of the singlemode fiber.
That power can ignite the acrylate coating on the fiber.
ADSS Cable Underground
Q: I'm installing an aerial run of ADSS cable and wonder
if I can pull the cable under roads in duct installed by
directional boring without splicing when I need to go
A: Yes you can pull ADSS cable in ducts installed by
directional boring without splicing. Just install the ADSS cable
link to the pole where you need to go underground and "dead end"
it at that pole. Drop the cable down, "figure-8" the cable to
prepare for the pull, then pull the cable in the duct. If you go
aerial on the other side, just continue the ADSS installation
Reflective Events Causing Transmission Problems
Q: I have a technical question about reflective events. I
recently assisted to troubleshoot an intermittent SM fiber link
for a customer. The cable was dug up a few years ago and a fiber
contractor has (fusion spiced) a different chunk of cable into
the link to repair it. When troubleshooting the link, I checked
the cable with the otdr. I found that each of the 12 fibers had
a reflective event at the fusion splice. This was only at the
splice tube closest to me. The other fusion splices in the other
tube were virtually invisible (as they should be). I'm a little
puzzled as to why there are reflections at the fusion splices. I
did a little research, but couldn't come up with a good answer
as to what is a possible cause of the reflections. (The OTDR
also showed a lot of ghosting on every fiber tested) (in some
cases it recorded over 40 ghost events) Although I haven't been
able to confirm that there is high Bit error rate due to the
transceiver not providing these statistics, (except for 3 out of
10 pings fail) I am suspecting that High reflectance is possibly
the cause of their unreliable fiber link.
A: Reflectance is a big problem in SM links, especially
short links. If you are seeing lots of ghosts, I suspect the
link is very short. Fusion splices can have reflectance if the
splicer is improperly set and the fusion is incomplete or has
bubbles. Those splices should have not only have reflectance but
higher loss. The solution is to open up the closure, use a VFL
to find the reflective events and redo the splices.
Blasting Near Fiber Optic Cables
have a project where blasting is planned near fiber optic
cables. We find no standards for this. Is it safe for the fiber
or should we treat it like other utilities like gas and water?
recommends considering fiber optic cables to be similar to gas
lines when blasting nearby. We know of no standards for this
but there are some descriptions of projects requiring blasting
near fiber optic cable installations. Here is a pipeline
company's guidelines for blasting. The guidelines seems
to focus on staying 5m from the fiber optic cable and using
careful blasting techniques.
Connector Protective Caps
Q:How do you clean LC Fiber Optic end caps (the cap that
covers the cleaned fiber cable)? Is there a tool for that?
A: We assume you are talking about the small plastic
protective caps on the connector ferrule. There is a joke in the
industry that goes “there’s a reason they call them "dust caps’”
they’re often full of dust.” The problem is these are plastic
molded parts that are made by the billions for various purposes
- some just fit fiber optic connectors. They come out of the
molding machine and are dumped in barrels. No provision is made
to keep them clean, plus they will have some mold release
chemicals inside them that can attract or hold dust. Even static
electricity is a problem.
We know no way to clean them nor to keep them clean. We
recommend using them to protect the connector ferrule - in fact
we’re trying to get people to call them “protective caps” - but
after they are removed and before use (connecting to another
cable or a transceiver or testing them) they need inspection and
See these pages in the FOA Guide: Microscope
Inspection And Cleaning of Fiber Optic Connectors Cleaning
Fiber Optic Connections
Directional Splice Loss
I have a customer that is splicing a fiber distribution hub to
their fiber plant. The fiber distribution hub utilizes
100FT long fiber stubs of SMF G.657.A1 and the fiber plant uses
SMF G.654.D. The project has a contract fusion splice
passing spec of 0.2dB loss, averaged bi-directional and also a
one-way <0.3dB loss (either direction) specification; using
an OTDR for measurements.
From my research, if the splices OTDR’s test results for the 2
directions are -0.2dB / +0.6 (average of +0.2), the network is
not actually seeing a +0.6dB loss; but this is how the OTDR
interprets the backscatter information… the OTDR being somewhat
confused due to the bend insensitive fiber characteristics.
A: Correct - the directional differences are due to the
mode field diameter variations in the two fibers. G.654 is
a large MFD fiber, ~12.5microns, compared to ~9 microns for
G.657.A fiber. The OTDR measures based on backscatter which will
be very different for the two fibers.
Markers For Underground Fiber Optic Cables
Q: I have a general question about above ground
markers for fiber optic cable in conduit. Is there a
recommended spacing for the markers? Is there a standard
to reference for this?
A: We asked some people who make them and they said the
guideline is “line of sight.” The rules for markers are
mainly what information needs to be on them. Of course we also
recommend adding marker tape about a foot above the conduit. I
was curious if there were any legal issues and I found this
interesting page from Cornell Law School: https://www.law.cornell.edu/cfr/text/49/192.707
So I might add to line of sight any crossings of roadways,
rail ways and some markers for bridge crossings.
We have a new section on the FOA Guide: Outside
Plant Fiber Optic Cable Plant Construction that may be
And Return Loss
Q: Help me understand measuring reflection little better.
Why do we consider -55dB to be a better reading than, say,
-25dB? If reflection and return loss are inverse readings and we
had a 55dB return loss, would that positive reading for return
loss be considered good?
A: Reflectance is measured as the ratio of reflected to
incoming signal at a connection. The confusion comes because
reflectance and return loss are inverse readings. Consider this:
If we have 1/1000 of the light reflected, the reflectance would
be -30 dB (1/1000 = -30 dB) but the return loss would be 30dB
since it is defined as 1000/1, the inverse, and is described as
Likewise, an APC connector would have a reflectance of -50 dB or
a return loss of 50 dB.
However, return loss as tested by all OTDRs is not be the
reflection from a single event but the total of all reflectance
events plus total backscatter from the length of fiber being
tested in the trace.
This is where most people are confused and misuse the terms.
questions are now available here on the FOA Guide.
Reading or Watching:
up at the FOA Pinterest
continuing quest to help people understand how to test fiber
optic cable plants and communications systems, we've created two
more "QuickStart Guides to Fiber Optic Testing." They are
simple, step-by-step guides on how to test fiber optic cable
plants, patchcords or single cables using insertion loss or OTDR
techniques and optical power from transceivers. It's as
straightforward as it can get - what equipment do you need, what
are the procedures for testing, options in implementing the
test, measurement errors and documenting the results.
It can't get much simpler.
Send anybody you know who needs to know about fiber optic
testing here to learn how it's done in a few minutes.
Fiber Optic Cable Plants And Patchcords
Fiber Optic Cable Plants With An OTDR
Optical Power In Communications Systems
Crossword Puzzles? Here's Some On Fiber Optics
Do you like
crossword puzzles? How about one on fiber optics - or maybe a
half-dozen of them? FOA Master Instructor Eric Pearson of Pearson
Technologies has created a series of crossword puzzles on
fiber optics that are keyed to the FOA CFOT reference materials
and his book Professional
Fiber Optic Installation, v.9. You can have fun and
study fiber optics at the same time!
This months crossword puzzle is on "Optoelectronics and
Splicing" - Download
the crossword puzzle on "Optoelectronics
missed the earlier puzzles, here they are:
the PDF file of the crossword on "Light and Fiber".
the PDF file of the crossword puzzle on "Cables".
the crossword on "Connectors
Fiber, Do You Know How Good It Is?
millions of miles of long distance fiber installed around the
world and most of it likely to see an upgrade of the systems
operating on it, probably in the near future. Twenty years ago,
most of it was probably running at ~1Gb/s, ten years ago it was
probably 2.5 Gb/s, recently it was likely to be 10Gb/s but now
many are being considered for 100Gb/s or beyond. Can the fiber
support such speeds? Can it be "repaired" or "modified" to make
it possible to use it at higher speeds? If you own that fiber,
can you say what it is worth without knowing its future upgrade
In order to know the potential for upgrades on your cable plant,
you need to test it. This process involves a number of tests and
is called "fiber characterization." Greg Stearns of TTP-US, an
FOA Corporate Member, performs these tests and has written a
short article on why you need to characterize fiber and how its
done. Read about fiber characterization from someone who does it
often and can explain it well.
the paper here (PDF, 80kB).
In The US Do Contractors Need Licenses For Fiber Optics?
get asked where in the US do contractors doing fiber optic
installations need licenses. We found a good website for that
information, the NECA -NEIS website. You might remember
NECA-EIS, as they are the partner with the FOA in the NECA/FOA
301 Fiber Optic Installation Standard. NECA is the National
Electrical Contractors Association and NEIS stands for National
Electrical Installation Standards. They have a very easy to use
map and table that gives you data on every state in the US, so
mark these pages for future reference.
(See “State Regulations”)
(all electrical licensing)
Low Voltage: http://www.neca-neis.org/state/index.cfm?fa=specialty_licensing
Fusion Splicing And Selecting Singlemode Fiber
We've been asked many times "How long does it take to splice a
cable?" It's not a simple answer as it varies with the number of
fibers in the cable and the work setup, including whether one or
two techs are working at a job site. FOA Master Instructor Joe
Botha of Triple Play in South Africa did his own analysis based
on decades of experience both splicing cables and teaching
others how to do it properly. This is one of the best analyses
we have seen because Joe includes prep times as well as splicing
times and differentiates between one tech and two techs working
together. He adds some other tips on fusion splicing too. This
should be mandatory reading for every tech and given to every
is Joe's splicing analysis.
Joe also has an excellent writeup on how
to choose singlemode fiber that helps understanding
the different types of G.6xx fiber. Read
And you will want to read Joe's report on splicing
different types of SM fiber, including bend-insensitive
(G.657) fiber. Read
- Mike Holt's Explanation Of The US National Electrical Code
(NEC) For Communications Cables
is the acknowledged expert of the US National Electrical Code
(NEC). His books and seminars are highly praised for their
ability to make a very complicated standard (that is in fact
Code - law - in most areas of the US) easily understood. Part of
the appeal is Mike's great drawings that make understanding so
much easier. Mike makes Chapter 8 of his book available free. It
covers communications cables, telephones, LANs, CATV and CCTV,
for premises applications. Even if you live in a region or
country where the NEC is not the law, you may find this
Mike's Chapter Here.
Technical Website For Installers
has one of the best technical website for cable installers. Check
out their website, especially “Videos,” “Engineer’s Corner”
and “Calculators.” http://www.polywater.com/NNNBSL.pdf
Optic Safety Poster
We've had numerous requests to reprint our guidelines
on safety when working with fiber optics, so we have
created a "Safety Poster" for you to print and post in your
classroom, worksite, etc. We suggest giving a copy to every
student and installer.
Tech Topics -
Fiber Optic Tester In Your Pocket? (See the video on
The camera in your old cell phone is sensitive to infrared light
- lots more than your eye - and can detect light in an optical
fiber or from a transmitter. Chris Hillyer,CFOT/CFOS/I,
Master Instructor, Northern California Sound & Communication
JATC brought this to our attention.
you have an old cell phone, try it. Our experience is that older
cell phone cameras have better sensitivity at IR wavelengths
than newer phones, so you may want to toss that old flip phone
into the toolbox.
YOKOGAWA OTDR Has Extended range, High Resolution And Multitasking
One OTDR manufacturer you don't hear as much about is YOKOGAWA
(formerly ANDO) which is too bad - they make some of the best
OTDRs, exemplified by this new model AQ7280. Need long range -
how about 50dB. High resolution - 0.6m dead zone. Like touch
screens, but for some functions want hard buttons, it's got
that. Options for VFL, microscope, light source and power meter,
etc. - it has that too.
But the unique aspect of the YOKOGAWA AQ7280 is it offers
multitasking - you can let do a trace with long averages while
you inspect connectors, make power readings, use the VFL or
info on the YOKOGAWA AQ7280.
thanks Yokogawa for a gift of an OTDR to use for R&D and
you read the FOA
pages on cleaning?