Wood

Should all panels be mounted on wood other than directly to concrete? I would think if the water begins to wick through the concrete then this exposes the panels to moisture. What are your thoughts?
Also, this panel is rated for 140amps and it has a 150amp main.

Direct mount to concrete is fine. The rating of the maximum breaker-size should have been included in the listing information, but generally, the breaker should not exceed the panel rating.

interesting…as I am not sure I have ever seen a panel rated for 140A but alas I have not seen everything out their thats for sure.

It is not uncommon to find an enclosure lets say rated for 225A but the main breaker in the panel is only 150A. This is fine but remember if those are the only two things you know then the panel is a 150A rated panel because of the weakest link theory ( I used to have a video for this online but thanks to a special person I was yanked…but I wont go their )

Lets also say you have a SE cable feeding the panel ( Service Entrance Conductor=SE ) that is rated 225A, with a main breaker of 150A and a conductor sized 4/0 AL which is good for 200A via 310.15(B)(6)…what is the service rating…150A due to the weakest link…

Hope this helps.

P.S. Their is no problem with the panel mounting to concrete, if the location is possibly a damp location lets say then you have to maintain the concerns of 312.2 which details the 1/4" air space behind the panel which is usually taken care of by the panel manufacturer. Give NEC 312.2 a view… personally I like installing panels on treated plywood when on a concrete wall…because it also affords me the ability to secure the conductors to the backing as it leaves the panel enclosure and just plain looks NEAT…:wink:

Gary
I’ve been an electrician and contractor for 37 years and I can assure you I have never seen or heard of a panel rating of 140 amps. All panels these days have protrusions on the back that holds the panel off the wall leaving an air space so moisture will not become a problem.

Gary
Iam not making it up, it has 140 amp marked in the panel. Unfortunately I don’t have a pic.

Hi Gary
Do you know the make of the panel?

Gary E
CH, here is a pic.

I would not worry too much on the mounting on the concrete wall issue. Not a wet location based on what I see and no real concerns to the mounting location.