[RE-wrenches] Fuse sizing in battery circuits

[Bob-O Schultze]

Even though the CBs may be more convenient, I'd opt for the Class T fuses because they are current limiting whereas CBs are generally not. In a direct short, the inrush current is huge. The T fuse will clamp that for a brief time and then blow. That works in your favor for heavy motor starting surges as well. I agree with Ray about the Boltswitch products.  Well built and hell for stout.
Bob-O

On Apr 8, 2013, at 7:13 AM, Ray Walters wrote:

I know you said that you would prefer breakers, but I've used Boltswitch pullout disconnects with class T fuses on many systems.  In the past 15 years, I've only blown 1 class T fuse, and they do offer better circuit protection.  Here's a PDF of some class T rated fused switches that are rated from 200 amp to 1200 amp DC.  See the series T models.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer, 
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 4/8/2013 7:57 AM, William Dorsett wrote:
> Have you tried Eaton/Heinemann breakers? Old number is (410) 546-9778. They’ve had some jumbo breakers that Trace used to use on their battery disconnects.
>  
> Bill Dorsett
> Manhattan, KS
>  
> From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Troy Harvey
> Sent: Sunday, April 07, 2013 9:39 PM
> To: Allan at positiveenergysolar.com; RE-wrenches
> Subject: Re: [RE-wrenches] Fuse sizing in battery circuits
>  
> Allan,
>  
> that is a good graph. Thanks. The time vs current is way different than whst I've seen from fuse charts in the past.
>  
> I'd rather use DC-breakers, but I'm having trouble finding 350AMP DC breakers for 350MCM cable. Any resources?
>  
> thanks,
> 
> Troy Harvey
> ---------------------
> Principal Engineer
> Heliocentric
> 801-453-9434
> taharvey at heliocentric.org
> 
> 
>  
> 
> 
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