Installing an ammeter/voltmeter for a subpanel

Old 12-14-17, 08:08 AM
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 1
Upvotes: 0
Received 0 Upvotes on 0 Posts
Installing an ammeter/voltmeter for a subpanel

I am helping a friend out and installing a 100amp subpanel in his garage 6 inches from the back of his 200amp main panel outside (Southern California). we want to monitor the amps used and whatnot for the whole panel so I bought this:

My question, is can you permanently mount this in the subpanel, or does it have to be outside the subpanel in a separate box? the leads off the CT are pretty short and i would run the main legs through the CT. I want to be safe and to code. I haven't found anything about this sort of thing, which makes me believe its not ok.
Old 12-14-17, 09:05 AM
Join Date: Feb 2014
Location: USA
Posts: 1,771
Received 0 Upvotes on 0 Posts
I don't know about the code, but I would mount it in a separate box next to the panel.
Old 12-14-17, 10:43 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 65,963
Received 4,148 Upvotes on 3,725 Posts
Welcome to the forums.

There's a fine line here. Code says panels shouldn't be modified. Covers are not specifically mentioned. I think those breaker locks/interlocks that bolt into the cover are iffy.

In my opinion.... it is not customary to modify a panel cover and install that meter in the cover. I would recommend installing it in a separate enclosure also.

They don't discuss connection to the panel with that unit. It needs to be connected to a 2P circuit breaker as it needs 240v.

I have similar devices on some of my pro equipment. I connect directly to the incoming lines that supply the panel but I use two fully insulated fuseholders and 5A 250v fuses for protection. This is my method. I'm not recommending it to you.... just mentioning it.
Old 12-15-17, 09:43 AM
Forum Topic Moderator
Join Date: Sep 2005
Location: USA
Posts: 6,177
Received 435 Upvotes on 387 Posts
I too would recommend a separate box. At some point in time, it'll die and will need to be replaced - and you'll end up having to cover a large cutout in the panel cover.

I would use something like this
Either in a 4x4 or 6x6 size depending on the size of the meter. Connect it to the panel with a short nipple.

It looks like you can easily extend the wires on the CT transformer.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: