# equipment ground conductor for PV arry?



## gabriel*PV (Nov 7, 2015)

Hello All, 

questions.? 

I work in los angeles california. I install PV systems for local solar company. 
we are having issues on what size equip grounding conductor size to use. 
the CODE BOOK show this:

250.166 Size of the Direct-Current Grounding Electrode
Conductor. The size of the grounding electrode conductor
for a dc system shall be as specified in 250.166(A) and
(B), except as permitted by 250.166(C) through (E). The
grounding electrode conductor for a dc system shall meet the
sizing requirements in this section but shall not be required to
be larger than 3/0 copper or 250 kcmil aluminum.


(A) Not Smaller Than the Neutral Conductor. Where the
dc system consists of a 3-wire balancer set or a balancer winding
with overcurrent protection as provided in 445.12(D), the
grounding electrode conductor shall not be smaller than the
neutral conductor and not smaller than 8 AWG copper or
6 AWG aluminum.


(B) Not Smaller Than the Largest Conductor. Where the
dc system is other than as in 250.166(A), the grounding
electrode conductor shall not be smaller than the largest
conductor supplied by the system, and not smaller than
8 AWG copper or 6 AWG aluminum.


Here is the question????
Is section "A" talking about the A/C side of the system or the D/C side.?

On the roof we use #10 RHW 90˚, so we should use #10 THWN-2.
(NOT #6 ) of course we have ( J) boxes to protect the #10. that aside. 

I have always done A/C solar tie ins with no less than a #8thwn, 
but this company is installing #6 egc from the arry to the main panel.

could someone please point me in the right direction to get the answer.

running a #6 EGC for 6. 35v 6amp models is a bit crazy!


----------



## Dennis Alwon (May 9, 2009)

An equipment grounding conductor is not the same as a grounding electrode conductor. 250.122 is for the equipment grounding conductor however there are times when the equipment grounding conductor can be used as a gec



> 250.121 Use of Equipment Grounding Conductors. An
> equipment grounding conductor shall not be used as a
> grounding electrode conductor.
> Exception: A wire-type equipment grounding conductor installed
> ...


----------



## Barjack (Mar 28, 2010)

I would also suggest taking a good, long look at Part V. of Art. 690, as it specifically applies to what you are asking.


----------



## macmikeman (Jan 23, 2007)

Dennis Alwon said:


> An equipment grounding conductor is not the same as a grounding electrode conductor. 250.122 is for the equipment grounding conductor however there are times when the equipment grounding conductor can be used as a gec



The problem you you Dennis is you keep stealing the words out of my mouth, mainly because I am sleeping and you are awake......:laughing:


----------



## backstay (Feb 3, 2011)

The ground wire that comes from the array is the equipment grounding conductor. It is sized from table 250.122 for the most part. The inverter will have a marked dc GEC terminal. That wire is sized from 250.166. It goes to the grounding electrode when accessible or to the service disconnect when not. #4 is larger than necessary but it allows you to not have to run it in conduit.


----------



## FaultCurrent (May 13, 2014)

250.166 (A) does not apply. This refers to balancer conductors used to equalize the loads produced by 2 DC gensets connected together in a 3 wire DC system.


----------

