Poured in place electrical

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marmathsen

Senior Member
Location
Seattle, Wa ...ish
Occupation
Electrical Contractor
We are going to be doing a single family residence that has a bunch of finish grade concrete walls with switches and outlets in them. I've done similar installations for stair light and retaining wall lights but there will be a lot in this house.

I was just hoping to get opionions from people on best practices. It doesn't sound like there are boxes or brackets specifically designed to get tied to the rebar or the forms. Floor boxes was all I could find that specifically details a poured concrete installation.

Weatherproof bell boxes or masonry boxes? Or maybe even some sort of plastic box?

Smurf tube (ENT) or pvc or carlflex etc?

Methods of attachment to the forms or rebar?

Thanks in advance for your responses or any additional input.

Rob

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Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
We use masonry boxes with pvc sleeve to accessible areas. You need to work closely with your contractor and the concrete form guys. Make sure they know what height and our form guys will usually fasten the boxes to the form. I think they put screws thru the box into the forms and then break them off when the form is removed.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
If you want PVC boxes Carlon for use with ENT makes a large selection:

http://www.carlonsales.com/mudboxes.php

A863S.jpg

There are also various metal boxes suitable for poured concrete:

https://www.clipsal.com/Trade/Produ...ANDARD-SIZE?c=1&ms=2&mg=355&g=3552694&cl=2957

A0001233.PNG
 

masterinbama

Senior Member

Adamjamma

Senior Member
Having done several in Jamaica what we usually do is nail through metal box to plywood sheathing... the nail bends easy enough to break later. But, also need to fill inside of box with paper, even twisting some down the pipes. Biggest problem is reaming the boxes out as the manufacturers knockouts are usually only 1/2 inch and I have found from experience that I need 3/4 or 1 inch. Use pvc male adaptors with the bushings into pvc pipe, and use springs to bend it... if I could find a good system of bending the ovals would switch to them.., but make sure you glue them as well.
At the panel area I have been spray painting my pvc pipes different colors and then using same paint color at the junction points in the walls, to help keep from losing track of which conduit is which.
Local method by most electricians is to put pipes only in place, then chase out the walls, put in boxes, but I have found it neater to put everything in before pouring concrete. Still a lot of work either way, but with more and more mud rings on the market, that is helping reduce the problems of finishing.
Now if manufacturers would make pvc boxes cheap in sizes like the metal ones. If you use the ones that can be ganged together, a hint is to go to the ones that the switch screw point is pointed in the box rather than out of the box... this makes less problems clearing concrete from the screws. Also, box can handle the three and four way switches without as many shorting problems. Just cannot find those in Jamaica so have to get them in Atlanta..lol...
 

Adamjamma

Senior Member
I always tape my conduit entries and pack the boxes with damp sand. Helps keep the concrete out and the sand can be removed with a shop vac.

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I had not thought of that. Have been using concrete bags and newspapers..lol...taping the conduits would let you label them as well, in case your notes went missing.
 
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