[RE-wrenches] Fuse sizing in battery circuits

[Ray Walters]

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.