Module grounding revisited [RE-wrenches]

[Greg Egan]

Brad, 

The following is my take on how to size the equipment grounding
conductor for a PV array. I KNOW there are more
experienced wrenches out there so fire away as needed. 

Art. 690.45 
..."equip. grounding conductor for PV source...shall be sized for 125%
of the PV originated short circuit current in that circuit." 

690.45 goes on to say if the circuit is protected by ground fault
protection equipment you need to use Table 250.122 to size the
grounding conductor. So for an example, if I had 12 Sharp 165 watt
panels in series, I'd only have a short circuit current of
5.46. So, either way you sized it,  (multiplying by 1.25 or using the
table) #10 would be more than adequate. 

Article 250.120 (C) states if the equipment grounding conductor is
subject to physical damage, it has to be larger than #6, so if
I thought the customer was going to be throwing hammers at it, I'd go
with #4. 

Greg 

I have a question about the size of the ground wire. I think I've read 
in the NEC that AWG #6 stranded or #8 solid is required where subject to 
physical damage. Does ground wiring in an array qualify as subject to 
physical damage (if the combiner is adjacent)? Or is #10 ground wire 
adequate? Since #10 or smaller interconnect wire seems to be accepted, 
maybe that's all that's needed for ground wire. Any thoughts? 

Thanks 
Brad Bassett 

-- 
Greg Egan 
Alaska Renewable Energy 
981 Gold Mine Trail Fairbanks, Alaska 99712 
Phone: 907-457-4299; Fax: 907-457-4290; Email: gegan at renewalaska.com 
URL:  http://www.renewalaska.com 
  
-- 
Greg Egan
Alaska Renewable Energy
981 Gold Mine Trail Fairbanks, Alaska 99712
Phone: 907-457-4299; Fax: 907-457-4290; Email: gegan at renewalaska.com 
URL:  http://www.renewalaska.com

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