2020 NEC Compliant 400A Common Disconnect Kit

[kkyyllee]

Good morning, my AHJ has received a request if this "common disconnect accessory kit" would be accepted to meet the requirements of the 2020 NEC 230.71B. Would you consider this to be a

2. Panelboards with a main service disconnecting means in each panelboard enclosure

You could operate each disconnect independently once the dead front is removed. This doesn't appear to meet the intent to me.

 

[wwhitney]

The definition of "disconnecting means" in article 100 is

"Disconnecting Means. A device, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply."

So the question is whether the Common Disconnect Kit successfully turns two disconnects (two individual devices that may each be operated independently) into a single disconnect (a single group of two devices which are operated together). If it does, then the service complies with the basic requirement of 230.71 "Each service shall have only one disconnecting means unless . . ."

Under the 2017 NEC, you could have an MLO panel contains multiple disconnecting means. If you used a 12 space panel on a single phase service and used 12 single pole breakers, that would violate the requirement of at most six "operations of the hand". But 2017 NEC 230.71(B) specified that if you used six handle ties to create 6 2-pole disconnects, that would comply with the limitation.

Thus the idea the handle ties change the number of disconnects present has a long history.

Cheers, Wayne

 

[Elect117]

I see zero issue with the concept. I do have some issues with that design.

1) I don't know how I feel about the screws being to the inside of the box and the act of sliding it requires the screws to not move or come lose. If they do, is there a possibility that one breaker will get snapped or broken by being torqued.

2) What happens when a breaker trips? Does the handle tie trip both circuits? Is there a risk that the individual breaker handles will break making their joint operation now impossible.

3) Is there a chance you have to remove the kit in order to work in that section? It appears to be a removable cover and is probably not an issue but that is also something to consider.

Code wise, the concept is okay. But in practice, I think this design can create a hazard.

 

[petersonra]

Seems like it is functional. One handle turns off everything. Kind of ugly, but it does the job.

 

[wwhitney]

1) I don't know how I feel about the screws being to the inside of the box and the act of sliding it requires the screws to not move or come lose. If they do, is there a possibility that one breaker will get snapped or broken by being torqued.

Those screws are presumably shoulder bolts, so that when the screws are tight the gap between the dead front and the base of the head is larger than the thickness of the sliding plate.

Cheers, Wayne

 

[kkyyllee]

Thank you for the feedback, everyone. I will follow up if I see one installed in the field with photos.