[RE-wrenches] Supply Side Tap Overcurrent Protection

[Eric Andrews]

We recommend to the customer to upgrade their service if it's not adequate
(old/outdated/too small).  In the grand scheme of things, that's a small
add-on.  Whenever there's a questionable interconnect, it's always prudent
to get a pre-approval from your AHJ and your utility.  A supply side tap may
be just as cumbersome as upgrading the service.  There is no magic "load
analysis" approval in the NEC for an owner load that's significantly under
loading their service.  I would say your AHJ will have the final answer on
your situation.  They will appreciate being brought into the situation
before work has been done.
 
Also, if the service panel is rated for 100 amps then you can legally
interconnect 20 x .8 = 16.7 amps per the 120% rule.  30A and 40A breakers?
 
Eric R. Andrews
NABCEP Certified PV Installer
 
>> 
>> 
 
    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
 
 
  _____  

From: Eric Andrews <eric at ecosolarnow.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Tue, March 30, 2010 10:25:45 AM
Subject: Re: [RE-wrenches] Supply Side Tap Overcurrent Protection



Nick-
 
Just downsize the main breaker.  For example, a 200 amp panel w/ a 200 amp
main breaker could be reduced to a 150 amp main breaker to allow for more
solar to be connected.  You need to calculate for the 120% rule.
 
Eric R. Andrews
NABCEP Certified PV Installer
 
 
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