receptacle boxes on basement concrete wall

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  #1  
Old 10-08-08, 12:33 AM
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receptacle boxes on basement concrete wall

I need to mount some receptacle boxes on my concrete wall in my basement. These will be below grade, so I think that this is considered a wet location. What are my options? Can I:

1) Use a 'typical' weatherproof grey alum. box mounted directly to the concrete, emt compression fitting threaded into the box, emt as sleeving up into the joist space, and emt-to-NM clamp, 100% NM-B

2) Use a 'handy box' non-weatherproof box mounted to the concrete with 1/4" plastic spacers between the box and wall, emt compression fitting, emt sleeving, emt-to-NM clamp, 100% NM-B

3) handy box directly to wall w/o spacers, emt compression fitting, emt sleeving, emt-to-NM clamp, 100% NM-B

4) something else


Do I need to hold the emt off the wall rather than bending an offset to run it next to the wall? (thinking that the 'wet' wall could allow water to run down the emt and into the box) Or does this not matter?


Thanks,
Rick
 
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Old 10-08-08, 05:54 AM
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I'd use grey surface mount pvc and put a GFCI on the first receptacle. You'd run THWN wires, running NM would be near impossible.
 
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Old 10-08-08, 07:50 AM
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Your basement should not meet the NEC definition of a wet location. If it does you really need to take care of those issues first. By NEC definition a wet location is "Installations under ground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather".

Handy boxes does not have enough cubic inch capacity to be used. A 3x2x1 1/2 box only has 7.5 cubic inches. A device counts as 2 conductors and the ground would add another. 3 x 2 cubic inches for 14 ga wire =6. You still would need another 4 inches just to add the black and white wires. I would typically mount a 4" sq. box with either a raised plaster ring or cover.
 
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Old 10-08-08, 09:00 AM
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Originally Posted by rockin_rick View Post
Do I need to hold the emt off the wall rather than bending an offset to run it next to the wall?
Flat to the wall with an offset is okay.

Unless you have serious drainage or foundation problems, the basement should not be a wet location, probably not even a damp location, but what I would consider a "normally dry" location.

Damp is defined as having no saturation, but "moderate degrees of moisture"; and goes on to list examples as "covered porches, some basements, some barns and cold storage warehouses".
 
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Old 10-08-08, 10:37 AM
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I would recommend using AC (Armored) Cable. It's a bit more expensive, but no need for conduit.
 
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Old 10-08-08, 03:44 PM
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Originally Posted by pcboss View Post
By NEC definition a wet location is "Installations under ground or in concrete slabs or masonry in direct contact with the earth...".
I had read this and perhaps I misinterpreted this as meaning that the entire surface of the concrete block basement wall that is underground would be considered a wet location, and thus the box mounted to it would be mounted in a wet location. Is this not true (assuming that the rest of the basement is a dry location)?

Originally Posted by pcboss View Post
Handy boxes does not have enough cubic inch capacity to be used. A 3x2x1 1/2 box only has 7.5 cubic inches.
Wow didn't realize that they were so small. I do fully know how to do box fill calcs, just hadn't checked into handy boxes yet. But I know I've seen them used as receptacle boxes before, evidently not to code... Since they're so small what are they used for (other than un-permitted installs, lol)? Pull points for a conduit run?

Thanks again,
Rick
 
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Old 10-11-08, 01:33 PM
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I just checked the handy boxes available locally at big box and they are listed as 11.5 cu in. So I could fit in a device with 12 AWG in (only). Perhaps these handy boxes are bigger than yours?

Thanks,
Rick
 
 

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