GEC/EGC 250.121 Exception 2014 NEC

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shortcircuit2

Senior Member
Location
South of Bawstin
Can I use the equipment grounding conductor in the SER feeder cable to a subpanel as the grounding electrode conductor for the connection to grounding electrodes under this new exception?
 

mwm1752

Senior Member
Location
Aspen, Colo
sizing is critical & a SER feeder EGC is usually sized to the OCPD not the service entrance conductors Cir Mil for a sub panel
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Can I use the equipment grounding conductor in the SER feeder cable to a subpanel as the grounding electrode conductor for the connection to grounding electrodes under this new exception?
Can you install it in a manner where all of the installation requirements for a grounding electrode conductor are met? Also why does a sub-panel need a grounding electrode conductor connection?

The rule and its exception needs to be removed from the code. The rule saying you can't use a EGC as a GEC went in the 2011 code, then in 2014 they added the exception. That really puts us right back where we were in the 2008 code.
 

bphgravity

Senior Member
Location
Florida
I like this exception and feel CMP 5 made a good decision reversing the prohibition in the 2011 edition. This option can save the installer a lot of time, materials, and money. There really is no safety or sound technical reason to not permit a conductor like an EGC to serve more than one purpose. The grounded (neutral) service conductor serves at least three purposes all at the same time. So why not double up an EGC as a GEC...
 

ActionDave

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Durango, CO, 10 h 20 min from the winged horses.
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Licensed Electrician
I like this exception and feel CMP 5 made a good decision reversing the prohibition in the 2011 edition. This option can save the installer a lot of time, materials, and money. There really is no safety or sound technical reason to not permit a conductor like an EGC to serve more than one purpose. The grounded (neutral) service conductor serves at least three purposes all at the same time. So why not double up an EGC as a GEC...
I like the exception too, but you wouldn't need an exception if you didn't have the rule, so why not just get rid of the rule and save some ink.
 

shortcircuit2

Senior Member
Location
South of Bawstin
Can you install it in a manner where all of the installation requirements for a grounding electrode conductor are met? Also why does a sub-panel need a grounding electrode conductor connection?

The sub-panel may be closer to the grounding electrode. So I could just connect the grounding electrode to the equipment grounding conductor in the sub-panel with a irreversible connection, thereby saving money by not wasting material and labor for something that is already installed and usable as the grounding electrode conductor.
 

shortcircuit2

Senior Member
Location
South of Bawstin
sizing is critical & a SER feeder EGC is usually sized to the OCPD not the service entrance conductors Cir Mil for a sub panel

Point taken...but for example the connection to Rod, Pipe or Plate electrodes only requires a #6 copper and connection to Concrete-Encased Electrodes only requires a #4 copper maximum.
 

bphgravity

Senior Member
Location
Florida
Having it written does add clarity - protection from those who don't understand that the code is permissive.

I agree. With the code being silent on the matter, one may feel the practice is not permitted where others find no such prohibition. This leads to inconsistent enforcement.

What leads you to believe the NEC is intended to be a permissive code when not otherwise explicitly stated in a "shall be permitted" type format?
 

bphgravity

Senior Member
Location
Florida
Sure. The NEC has many provisions for minimum compliance. But what if someone wants to exceed the minimum requirement with non-conforming practices?

Let's take a common one that has been discussed on this Forum in the past. Section 210.52(F) states at least one receptacle outlet shall be installed in areas designated for the installation of laundry equipment. Section 210.11(C)(2) states this one required receptacle shall be supplied by a 20-ampere branch circuit. So to comply with the code, I install a single receptacle in the laundry room and supply it with a 20A branch circuit. I have met the code.

Nowhere in the code does it say I can't install as many other branch circuits or receptacles in that room as I want once the minimum requirement has been met.. So, does this mean the code permits additional receptacles to be installed in the laundry room and supplied from perhaps a 15A branch circuit that also supplies other outlets not in the laundry room?

If the NEC is 100% permissive, it would have to prohibit everything not intended by a minimum code requirement. If the NEC is 100% prohibitive, it would have to give permission for every possible scenario. Shouldn't we consider this on a case-by-case basis?

That is, there are a few instances where the code intends something to not be permitted even though it is not explicitly expressed as such?
 

iwire

Moderator
Staff member
Location
Massachusetts
What code section would you cite if I installed a 15 amp branch circuit in addition to the 20 amp one I already installed in the laundry area?

If the NEC does not prohibit it I can do it
 

bphgravity

Senior Member
Location
Florida
So, why then do we need a 3XX.10 section for all the wiring methods and not just a 3XX.12 section? If the code is 100% permissive as you are all claiming, it would only need to tell us what is not permitted. No?
 
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