Tap rule?

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dwellselectric

dwellselectric

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Cape Cod, Massachusetts
On a job I roughed the homeowner has a solar company come in and install panels on the roof. I went to cut the panel in and saw this. Is this legal? They tapped off the 4/0 with #6's to feed the 60amp disconnect. I don't understand the tap rule it just didn't seem right to me.
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Looks like a supply s threeide PV connection, which is legal. AFAIK the conductors (if short) only need to be large enough to be protected by the 60A breaker.

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Supply-side connections are allowed for PV systems. (The relevant Code sections are found in 690.64 or 705.12, depending on what cycle you are working under.) While not technically a "service" per Article 100, these connections are often designed and built to the same standards. Hence a 60 A fused disconnect or larger is used. The allowable hardware for the point of common connection tends to vary by AHJ.

Mike Holt wrote a SolarPro magazine article a few years back that describes best practices for supply side connections.
 
dwellselectric said:
Thank you for the information :)
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FYI, some utilities would now consider this a 260A service ( I have come across this in Western Mass). So either the feeders would need to be upsized to carry 260A or a 200A main disco breaker would need to be installed ahead of the solar tap conductors.
 
Where did those tap conductors terminate ? (a disconnect ? located ? )
 
The tap rule does not apply here because solar panels are a source/supply, not a load.
 
csoc64 said:
FYI, some utilities would now consider this a 260A service ( I have come across this in Western Mass). So either the feeders would need to be upsized to carry 260A or a 200A main disco breaker would need to be installed ahead of the solar tap conductors.
Click to expand...

Really? The current flow options are pretty simple. The max current that can flow back at the utility is 60 A. And the max current that can flow to the loads is 200 A.

What's the 260 A scenario? (Dude reverse wires his PV inverter to illuminate the modules at night?)

The PV system isn't a load. If there is a fault and reverse currents flow to the PV inverter, it will be a short duration event that clears the fuses in ac disconnecting means.

I don't understand that interpretation. (Not to say it doesn't happen.) :slaphead:

If you put the 200 A main breaker ahead of the POI for the PV system, it's no longer a supply side interconnection and fall under the 120% rule. Supply side connections are clearly allowed by Code, and are limited only by the rating of the service.
 
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