Auxiliary Panel

[mathew stouffer]

Do the neutrals and grounds still need to be isolated in this auxiliary panel. I was not sure if the use of tap blocks would affect this. It is a 100 amps service disconnect with the tap blocks supplying power to the aux panel. One breaker is for an AC and the other is for some type of exterior lighting.

[Jerry Peck]

Do the neutrals and grounds still need to be isolated in this auxiliary panel.


Not sure what you mean by "auxiliary panel".

The above is why I keep stressing to think in terms of "service equipment" and 'other-than service equipment', i.e., just a "panel".

IF it is "service equipment" then the neutral is required to be bonded to ground.

IF it is just a "panel" (i.e., it is 'other-than service equipment') then the neutral is required to be isolated from ground.

Looks to me as though that is just a "panel" as it is 'other-than service equipment' - the "service equipment is in the enclosure on the right where the meter is, correct? The service equipment is where the main disconnects are and anything on the load side of the service disconnect would be a feeder and the feeder neutral would be isolated from ground.

[mathew stouffer]

Thanks Jerry.

[Rick Cantrell]

"Not sure what you mean by "auxiliary panel"."

Jerry, I think he means it's a "Subpanel":)

[mathew stouffer]

Holy **** I am getting beat up for that.

[Rick Cantrell]

FWIW
Looks like there are 2 100 amp breakers, that would make it a 200 amp service.

[Roger Frazee]

Hi Matt

First ... no one here misunderstood what you were asking by using the terminology "auxiliary panel". And since you didn't use the dreaded "sub-panel" word I thought the question was just fine.......:)

Anyway the point being if you refer to a panel that is not service equipment it is just a panel or panelboard or load center. If that panel is attached or in the same dwelling with the service equipment it will always have neutral and ground separated and should have a four wire feeder whether it is a tapped feeder or not. If it is load side of the service equipment in most cases this doesn't change that requirement.. However ... since the photos all but made the service equipment obvious I really didn't care what you called the panel next to it.

As you have noticed you have a tapped 4 wire feeder load side of the service equipment. In the panel serving the a/c and outside lights you have both equipment grounds and the feeder equipment ground landed on its neutral bar with the branch circuit neutral of a multiwire branch circuit for that 20 amp double pole. By doing this neutral current is going to be using the feeder neutral and feeder equipment ground to return to the service equipment and then to the transformer ..... this is essentially providing a parallel path. You do not want objectionable (system current) on the feeder equipment grounding wire.

Also notice in that panel that the 'green' bonding screw is installed through that metal strap. It needs to come out and not seeing any other location holes for a grounding bar to be installed in that panel..... One would have to be added....correctly. It could be that the strap removes and you use the holes under it to install a grounding bar ...I'm not sure.

So when you see a 4 wire feeder to a single phase panel load side of service equipment then you must have neutral and ground separated at that panel to prevent the parallel path.... it is that easy to determine.