# Which conduit system to use in poured walls



## RIVETER (Sep 26, 2009)

1940-b said:


> I'm going to be doing a residential job that has 10' tall x 8" thick exterior concrete walls and homowners want all outlets and switches in the concrete since the concrete will be the finished wall. What conduit/boxes are the best to use? PVC seems good for corrosion inhibiting since I've seen plenty of emt/metal boxes in concrete very corroded. Also thought of ENT. Suggestions?


I've not done it, don't know if it is legal, but I'll go with pvc. It has to be better and more reliable and labor saving.


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## freeagnt54 (Aug 6, 2008)

1940-b said:


> I'm going to be doing a residential job that has 10' tall x 8" thick exterior concrete walls and homowners want all outlets and switches in the concrete since the concrete will be the finished wall. What conduit/boxes are the best to use? PVC seems good for corrosion inhibiting since I've seen plenty of emt/metal boxes in concrete very corroded. Also thought of ENT. Suggestions?


Pvc is the best option in my opinion. Ent might seem faster but It always ends up needing more supports to hold it in place and it can by a pain to get a fish tape through.


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## 1940-b (Nov 14, 2014)

freeagnt54 said:


> Pvc is the best option in my opinion. Ent might seem faster but It always ends up needing more supports to hold it in place and it can by a pain to get a fish tape through.


What about boxes? Metal? I don't too many options in PVC for 3 or 4 gang boxes.


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## ponyboy (Nov 18, 2012)

Use deep 4 squares with mud rings. They won't compress or deform in the pour and give you plenty of room. Just tape em up


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## GatewaySparky (Jul 23, 2010)

I think PVC would be fine. you should check with your building inspector and/or engineer if you will be installing a lot of it in volume.


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## 1.21gigawatts (Jun 22, 2013)

Ive used ENT with duct tape and the boxes turned out well. We supported the boxes with 1/4" rod poking thru the mudring and wood forms with nuts and washers. Boxes were level and flush. We only lost a few out of hundreds set in the pour. The rods spin out after the forms are removed.


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## Bootss (Dec 30, 2011)

make sure you strap and secure those conduits and boxes well that cement can knock that stuff out of whack


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## Canadian sparky (Sep 19, 2011)

You need to support the boxes REALLY WELL..there's nothing worse than when they pry the forms off and you're box is on a 45 because you didn't support it properly..this is what we use up here in new high rise
http://www.royalbuildingproducts.co..._Fittings_Solutions/ENT Slab Box Brochure.pdf


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## Southeast Power (Jan 18, 2009)

We used to prefab metal boxes, mud rings on, all duct taped up with a sponge inside, with the connectors in them and tie wire through the boxes so that all we needed to do was drill a couple of holes through the forms and pull the tie wire through and then twist the wires together after the forms were up.
It's was easy for the carpenters to strip the forms by just cutting the tie wire.
EMT with taped up set screw fittings were the most reliable, first floor slabs were PVC. 
This was before smurf tube. I think smurf became more popular for horizontal runs and there are some products made by Carlon and others especially for slabs and direct bury in concrete.
3/4 PVC would be a good choice except for the weakness of typical fittings. You would have to tie wire it really tight to the rebar.


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## 220/221 (Sep 25, 2007)

ponyboy said:


> Use deep 4 squares with mud rings. They won't compress or deform in the pour and give you plenty of room. Just tape em up




Won't you end up with a weak spot around the mud ring where the concrete is thin ?


I've never installed boxes in poured concrete walls. How do you seal and secure the boxes to keep them flush and free from concrete?

I'd go masonry boxes, tape the holes/opening, pre install ground pigtails and figure out a way to hold them 100% tight to the form. Maybe 6/32/washer screw them thru the form, into the device holes?


EDIT: I like the sponge idea!


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## Techy (Mar 4, 2011)

220/221 said:


> Won't you end up with a weak spot around the mud ring where the concrete is thin ?
> 
> 
> I've never installed boxes in poured concrete walls. How do you seal and secure the boxes to keep them flush and free from concrete?
> ...


not if you use an 1 1/2" mudring, thats what i usually use for concrete work


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## eds (Mar 21, 2009)

What do you do when they use aluminum forms


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