EGC sizing question

csoc64

Senior Member
Location
northeast
If I oversize an equipment grounding conductor to avoid having to protect it if it is "subject to physical damage", do I need to then maintain that size to the panel? In this case, I'm using a #6 egc where it is exposed, circuit is 25A, so I would be pulling a #12 egc (in emt) from my jbox to the panel.
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
If I oversize an equipment grounding conductor to avoid having to protect it if it is "subject to physical damage", do I need to then maintain that size to the panel? In this case, I'm using a #6 egc where it is exposed, circuit is 25A, so I would be pulling a #12 egc (in emt) from my jbox to the panel.
What are you doing that the equipment ground is going to be exposed?
What about the Ungrounded conductors? Are they exposed also?
Silly question here by me, are you reading about grounding electrode conductors and not about equipment grounding conductors?
 

shortcircuit2

Senior Member
Location
South of Bawstin
I don't see anything in the code that says you have to upsize the EGC all the way back to the panel-board. So I say your good to go on the exposed part for the upsizing for protection...
 

kwired

Electron manager
Location
NE Nebraska
I think OP intended to ask about the GEC and not an EGC.


Just re-read OP, now I don't really know what he is asking about, seems to be mixing requirements for GEC and EGC together and applying them to whatever it is he has.
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
I am confused as to how the EGC got out of the EMT.
the original post:
If I oversize an equipment grounding conductor to avoid having to protect it if it is "subject to physical damage", do I need to then maintain that size to the panel? In this case, I'm using a #6 egc where it is exposed, circuit is 25A, so I would be pulling a #12 egc (in emt) from my jbox to the panel.

he said: where it is exposed.
Or did I confuse you? :0)
 

jumper

Senior Member
the original post:
If I oversize an equipment grounding conductor to avoid having to protect it if it is "subject to physical damage", do I need to then maintain that size to the panel? In this case, I'm using a #6 egc where it is exposed, circuit is 25A, so I would be pulling a #12 egc (in emt) from my jbox to the panel.

he said: where it is exposed.
Or did I confuse you? :0)
My confusion is as to why the EGC is exposed if the circuit conductors are in EMT.

I guess I am dense and missing something.:?
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
My confusion is as to why the EGC is exposed if the circuit conductors are in EMT.

I guess I am dense and missing something.:?
It looks like he is exposing the "EGC" from the j-box to the final connection. That's where I get confused if the EGC is exposed what about the other wires in the circuit? Are they exposed too?
 

charlie b

Moderator
Staff member
Location
Seattle, WA
The OP mentions a 25 amp circuit, so this is not a service, and we need not ask about GECs. I gather that there is a set of #12 ungrounded conductors with or without a neutral, and a #12 EGC, all run in EMT from the panel to a J-box. From that point, the wires run in open air, or in cable tray, or by some other "exposed" method, to the load. The OP wants to use a larger EGC in the exposed area. I think that is acceptable. The OP wants to not have to use that same larger EGC all the way back to the panel. I think that is acceptable as well.

What is not acceptable is the OP's statement that he plans to use a #12 EGC in a 25 amp circuit. You need a #10 minimum. Reference 250.122. What is also not acceptable, and this is an inference of mine and not a direct statement by the OP, is the use of #12 wires in a 25 amp circuit. I made that inference as a leap of logic from the OP's use of a #12 EGC. If that is indeed the OP's intent, then I would refer the OP to NEC article 240.4(D).
 

csoc64

Senior Member
Location
northeast
Sorry for the lack of detail here folks. My confusion stems from the fact that I'm jumping in on the back end of a project. Project is a dc roof mounted solar pv array. The egc in question runs under the array, picks up the rails on the roof and then runs from the roof (through emt with #10 RHW dc conductors) to a combiner box mounted on the wall of the building. Individual string circuits are approx 8.5A. There is probably a total of 10' of exposed conductor. I've been told that we run a #6 because only it is "exposed" to physical damage (according to some ahj's, although opinions have varied from town to town). The purpose of my initial post was to determine if I needed to maintain my egc sizing to the inverter. Hope this provides some clarification.
 

mwm1752

Senior Member
Location
Aspen, Colo
sound so solar -------- does the GEC have at least one continous path & or/why run an ECG unless require by specs? no confusingtonship here lol
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Engineer
I don't believe there is anything in the code book indicating that size XXX is OK where subject to physical damage. There's a few for GEC's, but even the #4 allowance for those has been removed from the code book.

Damage protection is up to the inspector. He may be happy with a larger/stronger conductor. Or he may want some structural guard. Or use EMT pipe. Or just tie/secure the thing often to follow some other structure so it will be difficult to damage.

There is no rule saying you can't upsize/downsize the EGC. You just have to use the minimum size or larger. So if you go big, you can came back down to #10 for a 25A circuit.
 
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