Piping in Can Lights

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macmikeman

Senior Member
One of my biggest fears when running emt thru floor joists is mystery compression of the joists themselves which would then collapse the 24'' gap between joist even with floor sheathing, that will damage the recess cans installed into the ceilings........... yep. Keeps me up all night sometimes.
 
The room is 22' wide and 32' long.
The floorjoists are factory made out of 2x4's and are 24" tall 22' long on 24" centers across a lower room.
The top is decked with 3/4" Tongue and groove OSB and is going to be used for storage.

JAP>

images

Are you describing floor joists similar to these? if so, future fishing of wiring is fairly easy.
 

jap

Senior Member
Occupation
Electrician
One of my biggest fears when running emt thru floor joists is mystery compression of the joists themselves which would then collapse the 24'' gap between joist even with floor sheathing, that will damage the recess cans installed into the ceilings........... yep. Keeps me up all night sometimes.


I'm glad I'm not the only one it bothers.


JAP>
 

jap

Senior Member
Occupation
Electrician
Do you also have the recurring nightmare of being entombed between floor and ceiling and crushed to death as people walk on the floor above?

No, but I think the sight of a can light trim that isnt sucked up tight against the sheetrock would be a bigger nightmare for me....:)
 

luckylerado

Senior Member
If there is that much deflection, the drywall will be cracking off the ceiling every time someone walks around on the upper floor. I think you are concerned about a non issue or rather one that should fall on the structural guy.

Did someone else in your organization bid the work for MC?
 

jap

Senior Member
Occupation
Electrician
BTW, while you guys were talking I wired them all in MC.

What's next boss?

I hate MC Cable with a passsion, much like most of the people writing job specs around here.
Although widely used in other areas, around here , the job specs generally limit the use of MC Cable or do not allow its use at all.


JAP>
 

jap

Senior Member
Occupation
Electrician
I guess that's where I got turned off on it.
Although I would have liked to have used it at times it was'nt allowed even when we tried to use it.
 

jap

Senior Member
Occupation
Electrician
If there is that much deflection, the drywall will be cracking off the ceiling every time someone walks around on the upper floor. I think you are concerned about a non issue or rather one that should fall on the structural guy.

Did someone else in your organization bid the work for MC?

No,
It was originally supposed to be a drop ceiling with metal studs.
All the receptacle, data, and switch stubups were to be installed in emt and tied together from box to box along the ouside walls and above the ceiling like normal.

The drop ceiling and metal studs changed to stud walls and wood floorjoists and a hard lid ceiling.
The switches, receptacles and data were still required to be in emt, but then everything had to be piped together inside the floorjoists since there was no access above the ceiling.

The question of the feeder conduits that turned down to the switches and receptacles arose seeing as how regardless of how strong the floorjoists and OSB are there is still some flex in them, and the switch boxes and receptacles were fixed to BB2-16 Box Supports in the 16" wall cavities.

I'm trying to avoid the conflict now that I'm there, but I like most, really never gave it a 2nd thought before this one.


JAP>
 

jap

Senior Member
Occupation
Electrician
Not me, love the stuff. 12/4 especially for starting branch circuits.

I guess its alright if you use a lot of it and have it laying around,or, if they sold it by the foot, but in this instance most of the homeruns are already pipe in.
 

Fulthrotl

~Autocorrect is My Worst Enema.~
No, but I think the sight of a can light trim that isnt sucked up tight against the sheetrock would be a bigger nightmare for me....:)

ok. you want hard pipe, and no pushdown.
now, that we have a picture, it's easier.

bend short 90's out of the top of the j box.
kick them so they lay alongside one of the truss zigzags.
you can cross the trusses or run parallel with one, doesn't matter.
tie wire them to the steel truss strut. they will scooch as necessary.

all the trusses we use here have steel tube lattice. if yours are wood,
use nail straps, and don't set them too hard.

there won't be any push down from vibration.

pull wire, make up before sheetrock, fold the wire nuts facing
the inside cover of the j box, so you can get to them later if needed.

me, i'd use stranded wire, but then again, i always use stranded wire.

make up with wagos, walk away.
 

jap

Senior Member
Occupation
Electrician
I think that's what I'm planning on doing.
I feel if the pipe can run along the truss instead of in between them, if there's any flex, it all should go up and down together.
Running the pipe perpindicular to the trusses shoulnt be an issue either.

Its when your running between the trusses on the filler blocks is where you get into trouble.

Was just needing second opinions.

Thanks,
JAP>
 

iwire

Moderator
Staff member
Location
Massachusetts
I hate MC Cable with a passsion, much like most of the people writing job specs around here.
Although widely used in other areas, around here , the job specs generally limit the use of MC Cable or do not allow its use at all.


JAP>

Almost every job spec we get shows EMT, yet almost every job we do is MC.

Why is that?


VE, value engineering, when we bid we bid it as EMT and provide an alternate for MC.


Most people paying the bill go for MC.

I prefer MC for most things, like can lights.
 
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