[RE-wrenches] Fuse sizing in battery circuits

[Drake]

Hi Ray,

Thanks for that information.  I'm glad they covered that. I never 
install more than a #4.

The question I'm still not sure of is weather or not we need to 
ground the DC.  I always have run a GEC to the DC.  It would be great 
if we didn't need to do so on the Sunny Islands especially, since 
they are not set up for DC grounding.

Drake

At 01:51 PM 4/16/2013, you wrote:
>Hi Drake;
>
>Read down a bit more and 250.166(C) and (D) limit the size of the 
>GEC to #4 or #6 max., depending on what electrode is used.
>This used to not be the case, and systems in the 90s had 4/0 cable 
>to a 5/8" electrode: which just like your 1/2" pipe example was 
>absolutely ridiculous.
>
>R.Ray Walters
>CTO, Solarray, Inc
>Nabcep Certified PV Installer,
>Licensed Master Electrician
>Solar Design Engineer
>303 505-8760
>
>On 4/16/2013 9:31 AM, Drake wrote:
>>
>>
>>So, in a standard battery system, with a charge control, ground 
>>fault protection and an array, the DC system will likely need 
>>grounding. If the DC system is grounded, then the battery cables 
>>are grounded also.
>>In 250.166 (B) it says the grounding electrode conductor (GEC) 
>>shall not be smaller than the largest conductor supplied by the system.
>>
>>If the battery cables are "supplied by the system" doesn't this 
>>imply that the GEC should be the size of the battery cable?  This 
>>is the logic that has led some inspectors to require a 4/0 copper 
>>wire to be bonded to a 1/2" water pipe. This is, of course, technically absurd.
>
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