[RE-wrenches] Supply Side Tap Overcurrent Protection

[Hans Frederickson]

Anything less than a 100A main is a no-go a for residential service:

NEC 230.79(C):
"For a one-family dwelling, the service disconnecting means shall have a
rating of not less than 100 amperes, 3-wire."

Also, I don't think any AHJ is going to accept a load calculation in lieu of
proper bus sizing in the service. What's to stop the owner from adding loads
later on? I agree with Eric... time for a service upgrade.


-Hans Frederickson
 

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Steven
Lawrence
Sent: Wednesday, March 31, 2010 9:54 AM
To: re-wrenches at lists.re-wrenches.org
Subject: Re: [RE-wrenches] Supply Side Tap Overcurrent Protection

Why can't you do a line side tap and downsize the main breaker?  Use a 60A
main disconnect for the line side tap, and use a 60A main breaker for the
service panel.  That's similar to what I did except I downsized the 200A
main to a 150A. This also allowed a manual interlock kit in the main service
panel that can be fed from the backup load panel.  

Steven Lawrence

______________________________________________________

Date: Wed, 31 Mar 2010 08:13:10 -0700 (PDT)
From: Nick Soleil <nicksoleilsolar at yahoo.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Subject: Re: [RE-wrenches] Supply Side Tap Overcurrent Protection
Message-ID: <342120.66732.qm at web44904.mail.sp1.yahoo.com>
Content-Type: text/plain; charset="us-ascii"

    Downsize the main breaker?  I would if I could, but the customer only
has 100 Amps now, and the solar is fed with two breakers, a 30A and a 40A.
So to be under 120Amps, I would have to size the main to 50 Amps, which may
be problematic.
    I can also do the line side tap, but had heard that a load analysis may
be accepted instead.  The loads of the house will never use more than 100
Amps.  I am wondering if any codes or white papers detail that option.  

 Nick Soleil
Project Manager
Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953
Cell:   707-321-2937
Office: 707-789-9537
Fax:    707-769-9037


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