[RE-wrenches] voltage drop

[R. Walters]

I have a volt drop spreadsheet on our website as well at http:// 
www.solarray.com/TechGuides/TGmain_T.php
It uses NEC temp correction for resistance, and another temp  
correction for ampacity. One is based on ambient air temp, and one is  
wire temp. All calculations are taken directly from the 2005 NEC 
( don't think wire changed in 2008) Also, it lets you look at various  
wires at the same time like William's. I don't currently have AC on  
it, but it's getting cold here, so maybe I'll add that this winter.
I hid the ampacity stuff I attempted, since NEC has so many factors  
to consider, but its still on there, if you unhide all the rows.  I  
also tried to do a sizing based on wire cost thing, but when wire  
pricing shot up, it threw all that off too.
You can still use that, you just have to enter your per ft cost for  
each wire size. The idea was to not spend $1000 putting in 4/0 cable  
to save $100 worth of solar power.


Ray

On Dec 10, 2008, at 8:16 AM, Wind-sun.com wrote:

> The NEC values are for 75C, but not everything operates at that  
> temperature (167F), nor or all uses of wire under NEC codes. I  
> understand why the spreadsheet is set up for NEC since that covers  
> probably 98% of all uses.
>
> At room temperature (25C), the resistance values are almost 20%  
> less - the "standard" physics value of #10 AWG is almost exactly 1  
> ohm per 1000 feet at 26C.
>
> http://en.wikipedia.org/wiki/American_wire_gauge
>
> ...................................................................... 
> ............................
> Northern Arizona Wind & Sun - Electricity From The Sun
> ...................................................................... 
> ............................
>
> ----- Original Message ----- From: "William Miller"  
> <wrmiller at charter.net>
> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> Sent: Tuesday, December 09, 2008 11:48 PM
> Subject: Re: [RE-wrenches] voltage drop
>
>
>> Dear Wind & Sun:
>>
>> What "standard" are you referring to?  We are using the 75C values  
>> from the NEC in order to assure code compliance.  We need to have  
>> a direct link to the NEC in case of compliance or liability issues.
>>
>> Thanks for asking.
>>
>> William Miller
>>
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R. Walters
Solarray.com
NABCEP # 04170442	



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