encased electrodes, and 250.52(A)( 3)
( 2) clarifies that, where more than one
concrete-encased electrode is present, it
is permissible to bond only one. In your
situation, the NEC requires a minimum
of one connection to a concrete-encased
electrode. It should be noted that this
requirement states that “it shall be permissible to bond only one,” recognizing
that, where there is more than one
concrete-encased electrode and all are
bonded, the net result is a better grounding electrode system.
Rigid conduit threadless
coupling for grounding
In an indoor installation of rigid metal
conduit (RMC), multiple points in conduit
runs made it infeasible to use threaded
couplings, so we used listed threadless
couplings. The plant engineer took
exception with the installation and
claimed that, since these were 480-volt
(V) feeders, we could not use the RMC as
an equipment grounding conductor (EGC)
because the conductors contained in the
conduit were more than 250V. An EGC
was installed with the feeder. However,
I have searched the NEC and not found
anything other than Section 344.60 that
permits RMC as an EGC. Can you help?
The scope of Article 344 covers RMC
and all associated fittings. Section 344.6
requires all associated fittings, which
would include couplings, to be listed.
Section 344.42(A) specifically permits threadless couplings. In addition,
250.118( 2) recognizes RMC as an EGC.
Nothing in the NEC would prohibit the
use of RMC as an EGC where listed
threadless couplings are used.
In the 2015 UL White Book, threadless
couplings fall under the product category
“Conduit Fittings DWTT.” This category
specifically permits listed threadless
couplings on RMC for grounding purposes. It permits threadless fittings for
use with EMT, RMC and intermediate
metal conduit for grounding purposes
without voltage limitations where they
are installed in accordance with the NEC.
Why aren’t all definitions
in Article 100?
The NEC has Article 100 for definitions,
but other articles contain definitions as
well. This can get confusing when trying
to apply a given Code rule. If there are
terms that I am not sure of, I find myself
looking in Article 100 and then in the
pertinent article. I think all definitions
should be placed in Article 100. Why are
they in different articles?
In the introduction to the NEC, Section
90. 1(A) clarifies that the NEC is not a
design specification or an instruction
manual for untrained people. NEC users
must understand Code arrangement. The
NEC style manual, which is available on
www.nfpa.org, governs the Code format.
The style manual requires definitions to
be in alphabetical order and prohibits
definitions from containing requirements
or recommendations. In general, Article
100 contains definitions of terms that
appear in two or more other articles of
the NEC, but individual articles may con-
tain definitions in the second section of
the article. The definitions in Article 100
apply globally throughout the NEC, and
the definitions in the second section of an
article apply only in that article.
It is extremely important that the NEC
user understands this format. It is essential to keep that separation. Adding all
definitions to Article 100 may sound like
a great idea, but that would actually create
confusion and misapplication. Definitions
necessary for application in an individual
article would be in Article 100 instead of
being logically located and easy to find in
the second section of an article.
For example, Article 517 contains 39
definitions necessary for the application
of NEC requirements for healthcare
facilities. They are located up front in
that article for clarity and usability.
Code users who are not familiar with the
requirements in Article 517 should familiarize themselves with those definitions
before attempting to apply requirements
within. Other issues would occur where
a defined term works in a given article
but not in other areas of the NEC.
DOLLARD is the safety coordinator for IBEW Local No. 98 in Philadelphia and works closely
with contractors to ensure job-site safety and compliance with all installation codes and
standards. He is a member of the NEC Correlating Committee, NEC CMP- 10, NEC CMP- 13, NFPA
70E, NFPA 90A/B and the UL Electrical Council. He can be reached at email@example.com.
Section 300.11 contains requirements for securing and supporting raceways,
cable assemblies, boxes, cabinets and fittings above ceilings.
Section 300.11(A) provides general requirements
that the equipment is to be securely
fastened in place.