[RE-wrenches] Supply Side Tap Overcurrent Protection

[Nick Soleil]

    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(old/outdated/too small).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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