[RE-wrenches] fewer wires, mo bettah?

[Hans Frederickson]

Marco,
In this case, slightly differing resistance between your grounded and
ungrounded conductors will not make any difference. You will just need to do
your DC voltage drop calculations for each half separately, instead of the
typical voltage drop calculation that uses wire length x 2. Different
resistance in parallel battery cables is an important issue, but that's not
what you're talking about.
 
Regards,
-Hans

 
  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Marco
Mangelsdorf
Sent: Monday, September 20, 2010 11:08 AM
To: 'RE-wrenches'
Subject: [RE-wrenches] fewer wires, mo bettah?



Check this out.

 

Four series strings of mods on a same plane roof feeding a larger Sunny Boy
or Fronius inverter.

 

Four #10 conductors for the ungrounded, fused (at the inverter) conductors.
And for the grounded conductor, a single, common, larger conductor from
those four strings.

 

So instead of four pairs of wires, or eight total, I'm using just five (plus
ground).

 

Assuming that the larger grounded conductor is adequately sized taking into
account conduit fill and temp derate for exposed conduit, does anyone see a
problem in doing this?

 

I've already been doing this for several years with no problems that I can
tell.  But it occurred to me whether different resistances between the
ungrounded conductors and the grounded conductor might be an issue.

 

Feedback appreciated.

 

Thanks,

marco

 

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