mounting of breaker panel

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SceneryDriver

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Location
NJ
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Electrical and Automation Designer
I've recently moved from the West Coast to the East, and I've just heard a new (to me) case of what I think is an inspector going overboard.

Is it a common practice on the East Coast for inspectors to require that breaker panels and conduit run in basements (considered a dry location) to be mounted on plywood, or otherwise be stood off from the cinder block/concrete wall? This is a residential application.

I can find no justification for this; I've run many hundreds of feet of EMT directly attached to brick and poured concrete walls and ceilings without problem or comment.

I've mounted many a breaker panel directly to the basement wall without standing it off. Have we all been doing it wrong all these years, or has this local inspector gone off the deep end? :) I'm hearing this secondhand, but the inspector is apparently claiming that it protects against some type of corrosion of the conduit. Consider me skeptical to say the least.

Thanks, all!


SceneryDriver
 
I think it is based on 312.2. Even though many panels have "dimples" that provide the 1/4" spacing, the dimples are still part of the enclosure and would be in contact with the damp basement wall. The question of damp of dry is a question for the AHJ, however, I see most masonry basement walls as being damp. (I am not saying that the basement itself is a damp location, although many basements are, I am just saying that the basement wall surface is a damp location)
 
Especially when the surface of the well is kept away from dry air by a mounted enclosure.
And the exudate from concrete, block or brick walls with earth on the other side can be corrosive.
 
It is just tradition in the Northeast and 'what the inspector likes to see'. Try to pin him down in code section and I bet they change the subject to other possible violations they could find. :rant:
 
iwire said:
It is just tradition in the Northeast and 'what the inspector likes to see'. Try to pin him down in code section and I bet they change the subject to other possible violations they could find. :rant:
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That's exactly what happened. It's "what the inspector likes to see." It bothers me when people roll over and do unnecessary work to placate an uninformed inspector. The "easier to do it his way than the right way" mentality drives me nuts. Doing things a certain way because of sound engineering is absolutely proper. Derpy opinions are not sound engineering.

I realize that mounting a panel on plywood isn't really a big deal, but in this case, the inspector is requiring that ALL conduit running across the block walls be stood off the brick with plywood.

If it's a damp location (which is most certainly isn't in this case) we should probably stop installing EMT outside. :blink: As for the corrosion issue, masonry is an alkaline environment (with a few exceptions). Steel actually lasts longer in that environment.

Standing off a panel in a damp location makes some sense, especially if the panel is NEMA 1. Doing the same for conduit does not. If it's damp, use RT fittings, though isn't that what THWN wire is for?



SceneryDriver
 
SceneryDriver said:
That's exactly what happened. It's "what the inspector likes to see." It bothers me when people roll over and do unnecessary work to placate an uninformed inspector. The "easier to do it his way than the right way" mentality drives me nuts. Doing things a certain way because of sound engineering is absolutely proper. Derpy opinions are not sound engineering.

I realize that mounting a panel on plywood isn't really a big deal, but in this case, the inspector is requiring that ALL conduit running across the block walls be stood off the brick with plywood.

If it's a damp location (which is most certainly isn't in this case) we should probably stop installing EMT outside. :blink: As for the corrosion issue, masonry is an alkaline environment (with a few exceptions). Steel actually lasts longer in that environment.

Standing off a panel in a damp location makes some sense, especially if the panel is NEMA 1. Doing the same for conduit does not. If it's damp, use RT fittings, though isn't that what THWN wire is for?



SceneryDriver
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mineralac straps:happyyes:
 
mjf said:
for future reference, that's a brand name with a large variety of strap styles.
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No doubt true but in my area if you order 'minnis' (Short for Minerallac) you will get a pipe hanger that looks like this ....

505781.jpg

... in any brand the supply house happens to be selling. :)
 
It may not be in the code, but there are decades of experience in this part of the country that tend to indicate that panels and metallic conduits/boxes in contact with basement wall will corrode and fall apart. It's not the moisture per se, but galvanic corrosion as a result of the ground current in those metallic objects and the steel sacrificing itself to protect the galvanized coating. Depending on the moisture levels, it can take from just a few years to a few decades, but the stuff WILL fall off the wall at some point, especially in older homes in developments where water runoff wasn't planned and high moisture is an everyday thing.
 
Amount of moisture on exterior side of that basement wall will effect how damp the interior side is.

Most new construction I run into they usually have better sealing, better drainage, or something that generally makes for a drier wall then you may see on older installations. People with new houses with a basement are generally utilizing that basement as part of their living space, damp exterior walls make for poor conditions for the living space - it invites mold, mildew, and allergy problems. There are places around here with high water table - you just don't build a home with basement in those areas or you build up the grade so moisture problems are minimized if you plan to have a basement.

If walls are frequently damp you likely will have corrosion problems with equipment mounted on them. If they are not damp, it is not much different then mounting same equipment on a similar wall that is not below grade.

If replacing an old service that has corroded severely - probably a good idea to at least space the new one off the old wall somehow, or use stainless or non metallic enclosures.
 
growler said:
To paint the back board is not really over kill.

You have to use pressure treated lumber and the new pressure treated lumber is very corrosive.
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And you have to watch what fasteners you use with newer pressure treated lumber or the fasteners will corrode away. Galvanized fasteners generally not a good idea.
 
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