"Point of Connection" To Tap, or Not to Tap" [RE-wrenches]

[Mark Frye]

Bruce,

I have been looking at this with a buddy who just went through it on a 
job he did, but this was a fused disconnect on the load side if the main 
disconnecting means.  The same argument was made by the AHJ that the 
point of connection was the tap not the fused disconnect, and this is 
not allowed.  I think it is pretty clear that the terminals in the fused 
disconnect are the “point of connection”.  The taps are just that, taps. 
I understand that a few major players in the solar field were consulted, 
but none were willing to weight in strongly against the determination of 
the AJH so....no go with the fused diconnect. Too bad for us all.

Here is my mental exercise that make this seem pretty clear to me. Prior 
to doing the solar work, I pull a separate permit to install a new 
branch circuit. I tap a feeder and install a fused disconnect. That’s 
it.  I don’t really want to connect anything to circuit, I just want to 
have it there.  I do not believe that there is anything in the code or 
in common sense that would prohibit my from doing this. Fine. Now I pull 
a permit to install a solar system, and the “point of connection” is the 
terminals in the fused disconnect. So in the end, what is the difference 
other than the AHJ imposing an interpretation that goes against common 
sense?

How is this different whether this exercise is played out above or below 
the main disconnecting means?

As far as the conductor size for these taps, the tap rules in Article 
240.21 define the allowable conductor size relative the length of the 
tap and the size of the OCP in the feeder and the branch (for the load 
side connection only).

As far as the line side connections, I think this is essentially a new 
service and the tap conductor need only be sized to the OCP in the PV 
system circuit referring to Article 230.

In a groundfault/short circuit situation in the service drop conductors, 
the only protection are the fuses at the utilty transformer anyway.  The 
OCP in the main is to protect the service drop conductors from more 
"long term" overcurrent so the conductors are matched in size to the OCP 
or vis-a-versa.

I have seen postings here egarding the nature of the line side 
connection being like a service but I haven't seen a thread here 
regarding the "point of connection" issue.

Good Luck.

Mark Frye
Berkeley Solar Electric Systems


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