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Emergency Power off (EPO) button for Generac generator

peter d

peter d

Senior Member
Location
New England
Have an inspector who wants an EPO on the side of house for generator in the backyard. It's a Generac. Is it necessary to interupt all 3 DC conductors or just the wire that controls the engine start/stop?
 
qcroanoke

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Sorta retired........
peter d said:
Have an inspector who wants an EPO on the side of house for generator in the backyard. It's a Generac. Is it necessary to interupt all 3 DC conductors or just the wire that controls the engine start/stop?
Click to expand...
Is it 15 kw or more?
And I'm not so sure breaking the start/stop wiring would do what you want. We put it in series with the estop button but all of ours is commercial not residential.
 
peter d

peter d

Senior Member
Location
New England
qcroanoke said:
Is it 15 kw or more?
And I'm not so sure breaking the start/stop wiring would do what you want. We put it in series with the estop button but all of ours is commercial not residential.
Click to expand...

Yes, 24 kw. I've heard the new generators come equipped with e-stop so we will likely just wire it in series with that one.
 
E

Ephraim Barlow

New User
Location
Colorado
Occupation
Electrical contractor
NFPA 70 (2023)
445.19 Emergency Shutdown of Prime Mover.

(B) Remote Emergency Shutdown.



For other than one- and two-family dwelling units, generators with greater than 15 kW rating shall be provided with a remote emergency stop switch to shut down the prime mover. The remote emergency stop switch shall be located outside the equipment room or generator enclosure at a readily accessible location and shall also meet the requirements of 445.19(A)(1) and (A)(2).
The remote emergency stop switch shall be permitted to be mounted on the exterior of the generator enclosure. The remote emergency stop switch shall be labeled Generator Emergency Shutdown, and the label shall meet the requirements of 110.21(B).





NFPA 110 — Standard for Emergency and Standby Power Systems (2022)
5.6.5.8.1
The remote emergency stop switch shall be located outside the room housing the prime mover or exterior enclosure and shall be permitted to be mounted on the exterior of the enclosure.
 
H

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
Interrupting the wire from the transferswitch will probably not shut the generator down, commercial units have a cool down timer, but residential is a little different. If it is a new generator, there probably is a terminal strip for connecting an external e-stop by removing a jumper, but I don’t know about Generac. I believe my Cummins RS20 has a harness for an external e-stop.
 
H

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
peter d said:
Have an inspector who wants an EPO on the side of house for generator in the backyard. It's a Generac. Is it necessary to interupt all 3 DC conductors or just the wire that controls the engine start/stop?
Click to expand...
Unless Generac has changed, the start/stop control is onboard at the generator. All the transferswitch does is send the utility voltage to the generator control board, which the generator makes the decision to start. Everybody else gets the start command from the transferswitch.
The dc wires only power the load shed relay board, and give the transfer signal to the switch.
 
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