[RE-wrenches] Parallel wire runs to increase size

[Nick Soleil]

That's true Dan.  "Not all of the current" would be on the larger wire, but most 
would be, assuming that the old #10 and the connections are still good.  And 
hopefully, it isn't landed on the 12V terminals on the back of the 
refrigerator.  


 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: Exeltech <exeltech at yahoo.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Wed, February 2, 2011 9:26:12 AM
Subject: Re: [RE-wrenches] Parallel wire runs to increase size


NEC 310.4 permits parallel conductors of 1/0 or larger.  Conductors smaller than 
1/0 are permitted, but with stipulations.

Nick's assertion "most if not all of the current will flow on the larger wires" 
is incorrect. The current will be shared proportionately between two paralleled 
conductors commensurate with their individual resistances.

The original query related to recreational vehicle PV DC-side installation, and 
referenced installation of a "second PV", implying only one existed initially.  
This would thus fall outside the bounds of the NEC, but shouldn't be interpreted 
to mean some of the common-sense aspects of the NEC aren't to be considered.

Dan



--- On Wed, 2/2/11, Jason Szumlanski <Jason at fafcosolar.com> wrote:


>From: Jason Szumlanski <Jason at fafcosolar.com>
>Subject: Re: [RE-wrenches] Parallel wire runs to increase size
>To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
>Date: Wednesday, February 2, 2011, 11:15 AM
>
>
>Nick,
> 
>Can you cite a code section that supports this. (not challenging you – it makes 
>sense and I agree)
> 
>I have been wondering about SMA’s recommendation to parallel two 1/0 cables for 
>a Sunny Island. If the wire sizes and  lengths are identical, is this 
>acceptable?
> 
>Jason Szumlanski
>Fafco Solar
> 
>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, February 02, 2011 12:05 PM
>To: RE-wrenches
>Subject: Re: [RE-wrenches] Parallel wire runs to increase size
> 
>You shouldn't parallel wiring that way.  That is not acceptable by code, and it 
>is unnecessary.   If the #10 is not sufficient just replace it.  Due to the fact 
>that the larger wiring has much less resistance, most if not all of the current 
>will flow on the larger wires.
> 
>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:"Starlight Solar, Larry Crutcher" <larry at starlightsolar.com>
>To: RE-wrenches  <re-wrenches at lists.re-wrenches.org>
>Sent: Wed, February 2, 2011 8:00:07 AM
>Subject: [RE-wrenches] Parallel wire runs to increase size
>Wrenches,
> 
>Some of our business involves repairing poor PV solar installations on 
>recreational vehicles. So often we wind up installing a roof junction box and 
>running a second PV to controller wire and then replacing the controller to 
>battery wire size. For instance, we may find a 10 gauge wire run to the 
>controller. We then add #8, #6, #4 or even 2 gauge and parallel to the #10 
>depending on power and distance of the run. My question: Is there a calculator 
>or chart that will tell me what the  combination of any two wire sizes equate 
>to? example: #10 + #4 = X
> 
>Thanks.
>Larry Crutcher
>Starlight Solar Power Systems
>powered by STARLIGHT™
> 
>-----Inline Attachment Follows-----
>
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