[RE-wrenches] conductors and the 120% rule

[Chris Mason]

The conductors have to be rated for 200A as normal. Fault current can only
come from the grid.
While the total available current on the bus of a panel is the total of the
source breakers, in the conductors, grid and solar power cancel out and the
total is not the sum of the two.


On Tue, Mar 4, 2014 at 1:05 PM, Kirk Herander <kirk at vtsolar.com> wrote:

> Hello,
>
> I have a 225 amp 3-phase main lug sub-panel protected by a 200 amp
> breaker. My inverter breaker feeding the sub panel is 60 amps. So 225 a bus
> x 1.2 = 270 amps. That's less than the sum of the two breakers of 260 amps,
> so no issue there. The conductors between sub and main panel have to be
> rated for at least 260/1.2 = 217 amps, correct? Is this 217 amps before or
> after derating the conductor?
>
>
>
>
>
> Kirk Herander
>
> VT Solar, LLC
>
> dba Vermont Solar Engineering
>
> NABCEPTM Certified Inaugural Certificant
>
> NYSERDA-eligible Installer
>
> VT RE Incentive Program Partner
>
> 802.863.1202
>
>
>
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-- 
Chris Mason
President, Comet Systems Ltd
www.cometenergysystems.com
Cell: 264.235.5670
Skype: netconcepts
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