Conduits to bottom of junction box

[RookiEE]

Hi All,

I have some outdoor receptacles and I am routing the conduits below floor for slab-on-grade floor. We usually specify 3/4'' conduit as minimum, can you have 3 of 3/4'' conduits entering the bottom of a junction box? Typically 4'' SQ or 4-11/16'' SQ junction box has 3 knockouts on the sides, mostly 1/2'' knockouts, I did found junction box with 3 - 3/4'' knockouts on the sides: https://www.emerson.com/documents/c...sion-rings-covers-catalog-pages-en-724286.pdf

Wondering if you can have 3 - 3/4'' conduits entering one side of junction box and if the box is common. Also after adding the locknuts, bushing, connectors etc, if still can connect 3 - 3/4'' into one side of junction box.
Is it common to route receptacles in a room in a loop so each junction box has only one conduit in and one conduit out? or branch out from one junction box and feed two sides of the room, and that junction box will have one conduit in and two conduits out?

Thanks.

 

[Eddie702]

As far as the J boxes you can have all the conduits out of 1 box or loop through a box with 2 conduits it can be doe either way. You just have to make sure the boxes are large enough for the contained conductors etc. Two conduits/box would be neater.

I would use 4 11/16 boxes for sure. I would use deep boxes if you have the room deep boxes. 3 3/4 KOs

 

[RookiEE]

Thanks for the input, anyone else can give input on this? Is it possible in the industry or is it rare that junction boxes have 3 - 3/4 KOs at the bottom side for conduits to enter? Rare but still available as the cutsheet I found? Fourth row 4SJD-3/4 on the first page has 10 - 3/4 KOs on 4 sides.

 

[electrofelon]

Thanks for the input, anyone else can give input on this? Is it possible in the industry or is it rare that junction boxes have 3 - 3/4 KOs at the bottom side for conduits to enter? Rare but still available as the cutsheet I found? Fourth row 4SJD-3/4 on the first page has 10 - 3/4 KOs on 4 sides.

(3) 3/4 on a side of a 4sq is tight, not sure if they would all fit. Just use a 4 and 11/16, they have (3) 3/4 from the factory.

How is this going to be finished? Is it something you want put a receptacle in in a finished wall? Or just a j box in a utility room? If the former, just use a mud ring. If the latter I might treat myself to a bigger box like a 6x6.

 

[rambojoe]

Its more common to bring homeruns above ceiling.. otherwise 4"11/16 always..

 

[RookiEE]

It's for exterior receptacle on first floor, so all conduits will be routed below slab and up to the bottom of junction box. Assuming its practical to use 4-11/16'' box with (3) 3/4 KOs plus the locknuts, bushing etc.

 

[electrofelon]

It's for exterior receptacle on first floor, so all conduits will be routed below slab and up to the bottom of junction box. Assuming its practical to use 4-11/16'' box with (3) 3/4 KOs plus the locknuts, bushing etc.

yes the 4 and 11 is fine for the 3 3/4. Using a fixed box for an exterior recep is often problematic. What is the siding material? I usually use a cut in box or an arlington in-box for exterior.

 

[RookiEE]

It's actually for a school, I believe the exterior walls are concrete, and also feeding outlets on the concrete bench at courtyard.

 

[infinity]

It's actually for a school, I believe the exterior walls are concrete, and also feeding outlets on the concrete bench at courtyard.

So these boxes will be recessed within the wall and finished with some type of flush receptacle covers? With 3 raceways a 4 11/16" X 2 1/8" deep box might work depending on how many conductors you're pulling. In thick walls you may also be able to use an extension collar box on the 4 11/16" box to increase the box volume.

 

[rambojoe]

I always use 4/11's because i can instantly know its a homer or a significant j-box...aside from-if it runs to a panel its probably gonna get add ons or chnge orders...

 

[RookiEE]

Yes they will be in wall and with WP cover, will be 3 circuits in one conduit.