what are some of the ways that a 120/240 service/breaker panel is installed in an unfinished basement block wall?? Is direct mounting ok , or does there need to be some kind of backing first so that the panel remains spaced from the wall??
Article 312.2(A) states that enclosures should be mounted so that there is at least 1/4" of airspace between the enclosure and the wall in damp and wet locations. If the location is not a damp or wet location, the enclosure should be mounted firmly secured to the surface it is mounted per Article 110.13(A).
Yes, you will notice that most enclosures listed for use in wet and damp (outdoors) locations have 1/4" protrusions (feet) at the mounting holes for this exact purpose.
Using wood is going to be a judgment call and more of a building code issue. It would probably better to use a metallic strut (unistrut, kindorf) for this purpose.
Some places require spacing off concrete. I think the specify wood but can't say now. Our co allways does it. Depending on the outside wall thickness sometimes just a sheet of plywood other times a few 2x4 and plywood. The panels always look in better shape if they were spaced off the wall. In the big developments they never space the panels off the walls.
As for being treated wood or strut I'm sure it's better but I don't feel It's nessisary. Up into to 1980's homes were built with standard wood on the foundation. Do you see that much of a rott problem? How many years do you expect out of a residential panel 40-60?
On that note, it isn't an NEC violation to have the panel mounted in a 2x4 framed wall, such that it has that 1/4" gap behind the panel?
We've had to fir our panels out--I assumed it was an insulation standard, to avoid a gap behind the panel that would go uninsulated and cause that flavor of trouble. I talked to the GC on our job today, and the AHJ we're dealing with told him that it was to protect the home runs going into the panel. Sorry, but that's not code, right?
Am I missing something, or is my wrath going to be unleashed for good reason?