[RE-wrenches] Supply Side Tap Overcurrent Protection

[August Goers]

Nick –

It would be great if a load exception could be made but I’ve never heard of it. Do you have any references to the code? -August

August Goers

Luminalt Energy Corporation
O: 415.564.7652
M: 415.559.1525
F: 650.244.9167
august at luminalt.com

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Nick Soleil
Sent: Wednesday, March 31, 2010 12:15 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Supply Side Tap Overcurrent Protection

    I feel confident that the load will not be over 80 Amps at any time, and therefore do not think that a service upgrade is necessary.  If the load is increased in the future (as in any situation,) the panel may need to be upgraded in the future.  By 'legal,' I assume you mean that it is approved by the applicable codes.
     I do agree that according to the 120% rule, the bussing is undersized, and a service upgrade would be a good solution.  However, I have heard that an exception can be made if a load analysis is provided.  My questions is specifically about the exception.  I have a firm understanding of my other options.
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: Wed, March 31, 2010 9:19:48 AM
Subject: Re: [RE-wrenches] Supply Side Tap Overcurrent Protection


We recommend to the customer to upgrade their service if it’s not adequate (old/outdated/too small).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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