[RE-wrenches] Gray code area

[Bill Brooks]

Drake,

 

They will not let you eliminate the box with the main breaker since the
conductors are run through the building. You are back to a load side
connection. However, since there are no loads pulled off that conductor to
the residential panel before the panel, connecting to the line side of the
residential panel makes it impossible to overcurrent the conductor. Most
inspectors will accept this method. The PV system will have to have a fused
disconnect at least as large as 125% of the sum of the full-current ratings
for the group of inverters, but it could be up to the ampacity of the wire
(I believe you said this was a 200-amp service). 

 

As long as you are feeding the service conductor from the opposite end as
the supply breaker, and there are no loads taken off that supply conductor
until the residential panel, you can make the argument that the sum of the
supply breakers is only 200-amps. That is because there is a 200-amp breaker
at one end, and a 200-amp breaker (PV) at the other end (the conductor only
can be supplied by 200-amps in either direction). In any fault analysis
scenario you can conjure up, there is no way to overcurrent the conductor.
Even a dead short in the wire can only carry 200-amps from each
direction-that is acceptable in standard fault analysis because the current
flow at the fault is disregarded. You have met the requirements of 690.64
(B). 

 

If you put it in the residential panel, you must comply with the 120%
rule--for now.

 

Bill.

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Drake
Chamberlin
Sent: Thursday, July 31, 2008 7:53 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Gray code area

 

Bill,

That is a great point.  As it stands, the box ahead of the residence does
contain a main breaker.  If we get rid of that breaker and turn it into a
lugs only panel, it would satisfy the requirements.  I wonder how that would
pan out, since the wiring runs through this other building.  

Thanks,

Drake 


At 12:49 PM 7/31/2008, you wrote:



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Drake,
 
690.64 relates everything to the service disconnects. All the rest of this
is semantics. As long as the PV connection is upstream of the service
disconnect (i.e. in between the service disconnect and the service meter),
it is considered a line side service connection.
 
If there is no way to turn off the residential service in the panel with the
"feed-thru" lugs, there is no service disconnect for the residential service
yet. That way if the connection were on the line side of the first service
disconnect for the residence (one of two services at the site, both coming
from the same service drop-to get all the semantics proper), it is
considered a line-side connection. So what is it..?
 
Bill.
 
From: re-wrenches-bounces at lists.re-wrenches.org [
<mailto:re-wrenches-bounces at lists.re-wrenches.org>
mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Drake
Chamberlin
Sent: Thursday, July 31, 2008 9:13 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Gray code area
 
At 03:24 PM 7/30/2008, you wrote:

According to the two paragraphs above, the commercial building has two
commercial services???  One will receive PV and one will not??

One service is for the commercial building and one is for the residence.
There is one service drop to two meters.  Both services will be fed PV. 


Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
740-448-7328
303-328-5533
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Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
740-448-7328
303-328-5533

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