1. THE 10 MOST COMMON NEC® VIOLATIONS IN OUR INDUSTRY.
By: Santiago Beron, RCDD, CTS
It is sad how sometimes the responsibility of NEC® code compliance is shifted from one
party to another in projects that include low voltage systems. The designer clears the
responsibility with a paragraph in the specifications that usually reads “The contractor
shall comply with all codes and regulations”. The contractor executing the job shifts
responsibility of code compliance to the engineer of record, since the job was permitted
with drawings signed and sealed by the engineer of record. The engineer of record
usually designs all the electrical system and maybe “raceways only” for the low voltage
systems, but it is very likely that he/she was not responsible for the design of the low
voltage systems, so the low voltage design was really never under his/her responsibility.
RCDDs who design and install low voltage systems are (fortunately or unfortunately) the
party most suitable to check a design for code compliance, regardless if they are acting as
designers, contractor or possibly as engineers of record. Unfortunately the knowledge of
the code sometimes is believed by many to be limited to plenum or non plenum rated
cable decisions. Most low voltage training that is out there in our industry really does not
address in detail code issues. There is specialized training for code issues, but when you
sit through one of those you fill there is a big disconnect between what you see out there
in the field and in manufacturer’s stands and the explanations and terminology used in
those code seminars.
A very typical false belief in our industry is that if a project passed an inspection by a city
official or inspector it means that it is a code compliant installation, so it is believed the
designer and/or contractor did the right thing. This is false also, in many cases it just
means the issues were not caught by the inspector. I have seen new buildings recently
completed with code violations. There are two reasons why inspections don’t report code
violations in low voltage systems very frequently. The first reason is that in many
projects the general contractor or construction manager calls for a electrical inspection as
soon as the electrical work is completed, but as we all know the low voltage trades are the
last ones to leave the premises. So by the time the inspections take place the low voltage
work is not complete or sometimes just getting started. The second reason is that
inspectors themselves are very focused in the “mayor” systems like fire alarm and
electrical systems. They are supposed to, and in fact do check, low voltage work; but to
them it is not high in their priority list and with so many details to remember in the
“mayor” systems, the inspectors seldom go into great detail in the low voltage systems.
In an effort to help bring clarity to code issues I have prepared a list of the most common
NEC® code violations in our industry. This list references the particular NEC® 2005
code paragraphs that are broken. They are not listed in any particular order.
1. Audio cables run in cable trays with other low voltage cable. NEC® 2005
introduced a new article (725.56.F) that prohibits audio cables (speaker,
microphone or line level signals) to be run in the same raceway with other Class 2

2. or class 3 circuits (low voltage power and network cables). This is a common
violation especially with audio systems that work on twisted pair cables. It is a
common misconception to say that all cables of the same type (i.e. CAT5e cables)
can be run together because they are the same cable type. In this case the code
dictates the wiring method for this circuit depending on the purpose of the circuit
not based on the cable type.
2. Power cords run above ceilings. Article 400.8.5 prohibits running flexible power
cords above ceiling. Sometimes when TV displays or projectors are suspended
from the roof or slab structure, power outlets are placed above the ceiling to
connect those devices. A variation of this code violation is running power cords
below the raised floor used for air distribution in computer rooms non-compliant
with article 645. This violation is mostly related to electric work and not to low
voltage systems, but I’m including it because it is driven by power requirements
in low voltage systems.
3. Cables suspended from a cable tray system. It is very common to see low voltage
cables strap to the bottom of a cables tray system. Article 392.6.J, allows this
support method only in industrial installations serviced by qualified personnel. In
commercial building it is ok to strap from the tray but additional supports are
required. Most likely this article was written thinking of heavy power cables, but
unfortunately there is no exception for low voltage cables. It does not seem to be a
big deal or a really hazardous situation, but this is being analyzed only from the
code compliance point of view. A spin-off this code violation is also supporting
low voltage cables from electrical raceways. Article 800.133.C prohibits this
practice.
4. Unlisted broadband backbone cables run inside the building for more than 50 ft.
Article 820.113 exception 2 limits unlisted broadband (coax) cables to 50 ft from
point of entrance. In commercial buildings with requirements for large bandwidth
system and because of attenuation issues, it is required to run PIII-500 or 650
coaxial backbone cables to maintain the signal. These cables are usually made for
outside plant applications and the offering in riser rated versions is very limited,
so that is why is easy to fall for this one.
5. Secondary protection used in lieu of primary protection. Article 800.90.D states
that secondary primary protection can not be used without primary protection.
This requirement is not only for telephone cables but for other low voltage
circuits like Class 2 wiring or audio systems. The code violation comes when
installers or designers install/design a protection module without knowing the
classification of the protector. Primary protectors are listed under UL 497,
secondary protectors are listed under UL 497A. The similarity of the UL numbers
and the failure of some manufacturer to use the same terminology of the NEC®
(primary or secondary protection) make it easy to install/design the wrong device.
6. Patch cords run in plenum spaces. Article 800.154.A explains that only CMP
rated cables can be run in plenum spaces. This is not a big surprise for most
people in our industry but with the proliferation of wireless access point and IP
cameras it has been required to terminate horizontal cables above ceilings,
creating code issues. Because of the need to test the cable for those applications,
jacks are installed also above the ceiling. The code violation comes by leaving the

3. jack exposed to the plenum and/or using a factory made patch cord (rated as CM
or CMG only) to make the final connection to the device.
7. Low voltage cables run from multi-output power supplies with non class 2 rated
outputs installed in the same raceway or cable tray with other low voltage cables.
Article 725.55.A does not allow running Class 2 and Class 3 circuits with power,
lighting and Class 1 circuits in the same cable or raceway, except for very limited
cases. In our industry there are a lot of multiple output power supplies (i.e. for
CCTV cameras and access control systems) that because of the way they are built
they are not classified as Class 2 outputs but Class 1. Unfortunately the
installation manual for those devices don’t mention explicitly Class 1 anywhere in
the document, they just don’t mention Class 2. It is too easy to fall for this code
violation.
8. Ungrounded or improperly grounded primary or secondary protectors. Article
800.170.A and 800.170.B estipulate that all primary protectors need to be
grounded and secondary protection needs to be grounded when present in the
device. In our industry it is well know the fact that primary protectors need to be
grounded. The code violation comes most of the time by running excessive
lengths of ground cable to reach a distance ground bar when other grounding
means are closer. Secondary protectors are installed many times as a result of a
specific situation when equipment got damaged. Those retrofits jobs are done
many times by unqualified personnel who are not aware of the grounding
requirements for secondary devices.
9. Unlisted communication cables coming into the building in EMT conduit and
extending beyond 50 ft. Article 800.2 defines point of entrance as “the point at
which the wire or cable emerges from the external wall, from a concrete slab or
from a rigid metal conduit or an intermediate metal conduit grounded to an
electrode”. The code violation comes when assuming that EMT conduit is also ok
to extend the point of entrance. Electricians don’t like using rigid metal conduit
because of the treading of the conduit ends and because is a heavier pipe, and in
“their” world the point of entrance can’t be extended with pipe.
10. Insulated grounding backbone cables run in air handling spaces in the cable tray.
Insulations for large gauge (3/0 or AWG-6) electrical cables are usually not listed
for plenum use, since their main use is in for electrical work, where they are run
in conduit. Article 800.154 is clear in requiring cable listings for plenum use. The
code violation comes when running those cables as telecommunications
grounding backbones (or other grounding wires for telecommunications) in the
cable tray system with other low voltage cables. They are installed in the cable
tray because they are not current carrying conductors. Fortunately BICSI and TIA
have revised the concept of the telecommunications grounding backbones and
those long grounding backbones are being eliminated. It is good practice to say
with un-insulated cables or run separate conduits for those cables.
I’m sure some of you are thinking of other common violations, but for now we will just
keep them to 10. As I said before, they are not listed in any order, since I have no data to
corroborate which of those occur more frequently.

4. RCCD’s should make an effort to keep up to date in all the code changes. I know reading
the code is confusing and dense and many times you can’t find straight answers, but if we
don’t make this effort, chances are, nobody else will.