Emergency Disconnect for 1 or 2 family dwelling

Merry Christmas
Grouch

Grouch

Senior Member
Location
New York, NY
The 2020 NEC introduced the emergency disconnect for a 1 or 2 family household in section 230.85. The NYC amendments added an exception to that section, stating the following:

Section 230.85 – Add an Exception at the end of Section 230.85 to read as follows:

Exception: If the emergency disconnecting means cannot be located in a readily accessible outdoor location, or if the utility metering equipment is located indoors, 1 of the following disconnecting means shall be permitted:
1. A remote disconnecting means provided by the utility
2. An indoor shunt-trip disconnecting means with the control device located in a readily accessible outdoor location and marked, “Remote Emergency Disconnect”
3. An approved equivalent means

My question is regarding #2, with the shunt-trip. How do you power the control device located outside, that controls the indoor shunt-trip breaker? Do I bring 120 volts to the control device by tapping off one of the hot wires of the service entrance conductors? It would seem strange to bring 120 volts from a panel inside the house, since that panel would be on the load side of the shunt trip emergency disconnect and service equipment.
 
I would power the shunt trip off one of the branch circuit breakers in the indoor panel. There is no way I would use unprotected service conductors.
 
don_resqcapt19 said:
I would power the shunt trip off one of the branch circuit breakers in the indoor panel. There is no way I would use unprotected service conductors.
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It's just strange. You hit the shunt trip, and you would immediately lose power to that shunt trip. It doesn't matter I guess, since at that point power is disconnected from the dwelling anyway.
 
Grouch said:
It's just strange. You hit the shunt trip, and you would immediately lose power to that shunt trip.
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If the shunt trip coil is not rated to be continuously powered, and if the breaker doesn't have an internal mechanism to disconnect the coil when off, then the above behavior is a necessary feature to avoid burning up the shunt trip coil.

I have no idea if most/all shunt trip breakers have such an internal mechanism, just that the couple I have installed state in their documentation they do, so I didn't have to worry about the issue.

Cheers, Wayne
 
Grouch said:
It's just strange. You hit the shunt trip, and you would immediately lose power to that shunt trip. It doesn't matter I guess, since at that point power is disconnected from the dwelling anyway.
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You have to manually reset the breaker so no need for any power to the button have you have activated the shunt trip,
 
Grouch said:
It's just strange. You hit the shunt trip, and you would immediately lose power to that shunt trip. It doesn't matter I guess, since at that point power is disconnected from the dwelling anyway.
Click to expand...
Other shunt trip applications often do receive shunt coil voltage from the same circuit that is being interrupted. This method also assures you don't leave the shunt coil energized after closing the switch that actuates the shunt coil. Which can prevent burning out the shunt coil if it is a type not intended for long term energization, which some might be.

I wouldn't want to tap the service conductors even if you put an overcurrent device near the tap, would still leave you with that control circuit within the building still energized, part of the idea is you are supposedly de-energizing all the wiring in the building when you operate that emergency disconnect switch.
 
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