[RE-wrenches] Fuse sizing in battery circuits

[Ray Walters]

Hi August;

250.162(A) says "operating at greater than 50 v", which a 48 v nominal 
system operates most of the time at over 50 v, at least when solar 
charging and/or selling back.
We used to get dinged many years ago for using breakers rated at 50v dc 
on 48 v systems.  John Wiles used to insist we use the highest possible 
voltage (Voc of modules on coldest day)
Personally I prefer ungrounded systems, so I'm not saying there's 
anything wrong from a safety stand point, just that inspectors here 
don't see it the same way.

R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

On 4/15/2013 2:20 PM, August Goers wrote:
>
> Hi Drake,
>
> The Sunny Island System runs at 48 V nominal so I don't believe 
> 250.162(A) applies. We have some really savvy inspectors in the Bay 
> Area and they were happy for us to be ungrounded since we're operating 
> at 48 V. Yes, the actual voltage might go above 50 V when charging but 
> I believe it is the nominal voltage that the code cares about.
>
> Best,
>
>

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