MECKLENBURG COUNTY
Land Use and Environmental Service Agency
Code Enforcement
3/9/11 ELECTRICAL CONSISTENCY MEETING
Code Consistency Questions
1. Do all low voltage devices have to be installed to approve a final?
Yes, No, and Maybe. There are so many varieties of low voltage installations that are going to
be installed at so many different stages of construction that it is not feasible to say that ALL
low voltage devices must be installed at the final inspection. The following is a guide to what
is required:
 All code required low voltage systems must have devices and system fully
installed.
 All systems or portions of systems that will be energized when power is turned
on must have that system or portions fully installed
 All systems that have wiring un-terminated and for future use, must have that
wiring protected and tagged for” future use.”
 All components that require grounding must be grounded per code.
 All installed components, devices, etc shall be labeled and listed
2. What is required for an Industrial Machinery exemption?
First you must become completely familiar with the Department Directive on Industrial
Machinery found on our website at:
http://charmeck.org/mecklenburg/county/CodeEnforcement/Electrical/Documents/IMandFAQ.
pdf
Next a Declaration Letter described in the Directive must be submitted by the owner or officer
of the business to the authority having jurisdiction and / or the inspector on the job for review
and documentation. Finally the inspector will evaluate the machinery at the installation to see
if it meets the intent of GS 143-138(b), and if so, inspect the job accordingly.
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3. When does work have to be brought up to current code?
This is an issue that for the most part has to be evaluated on a case-by-case basis; in
general all work must meet the current code. Some specific replacement/repair work
guidelines such as flood & fire damage, remodel jobs, kitchen cabinet replacement and
existing bathroom remodels can be found in the Electrical Interpretation page of our
website as follows:
http://charmeck.org/mecklenburg/county/CodeEnforcement/Electrical/Pages/Electrical
%20Interpretations.aspx
4. The central vacuum system installer installed a bunch of their suction outlets
onto existing electrical receptacle outlets. In some cases these existing outlets
are 20 amp wire and breakers. The wire that comes from the assembly is a five
foot length #14 AWG. He says UL allows this as the devices are listed. Is
this correct?
No. the items are a recognized component, not a “listed system”. UL
White Book DMLW NEC 422.15(A) which references 210.23(A) and also
422.15(B) which states that the conductors cannot be less in size than the
conductors they connect to.
5. I have a 3,000 amp service and two 2,000 amp services in the same room. The water
main is located 400 feet away. A designer insists that I install either three separate 3/0 AWG
copper grounding electrode conductors or two 300 kcmil conductors in parallel. May I run a
single 3/0 AWG copper wire from a bus bar (1/4” x 2” x 12”) that is in the room containing
these services to the water main to serve as the ground for all the services and connect each
service to this bus bar?
Yes, A common grounding electrode is acceptable. The 250.64(a) thru (F) of the
2008 NEC makes it clear that a common GEC must be a 3/0 cu conductor. While all three
services could fail, they would not all fail at the same instance. The grounding electrode
connection is not there to open an overcurrent device and when you look at an installation if
there are just made (rod) type electrodes
a #6 is the maximum size required. A separate grounding electrode conductor shall be run
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from each electrical service to a grounding electrode or a common grounding electrode
conductor. 250.58 requires the same electrode(s) be used as the common tie point for all
services. 250.64(F) allows the installer to use a bus bar for connecting “(B) bonding jumpers
from grounding electrodes “if there are more than one. Typically each service may be
connected with a properly sized EGC to the closest steel framing member and the steel frame
is grounded properly per 250.52(A) (2).
6. There have been several questions regarding CSST bonding come up, We need some
clarification. Do we require # 6 per mechanical code or do we require bond per CSST
installation instructions?
Yes. 310.2 CSST Bonding of the Fuel Gas Code states: CSST Gas piping systems shall be
bonded to the electrical service grounding electrode system at the point where the gas service
enters the building. The bonding jumper shall not be smaller than 6 AWG copper wire or
equivalent. If the manufacturer’s instructions call for a size larger than #6, then it must be
used, otherwise we use 310.2
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