Poke-Thru Junction Box Clearance Below

[mwagner]

This question is relating to the poke-thru devices with the junction box on the end attached to conduit. I am wondering if that box needs to follow the same rules as other junction boxes in the NEC in that it needs to be accessible? It seems weird that these floor devices would require access right below them while floor-boxes with the conduit run in the slab don't need any sort of removability.

I looked online but I didn't see anything saying anything about this and I even checked a few product manuals. I have been making sure that there is enough space to get a ladder up to these, but a column of clearance is very inconvenient for the trades.

What are everyone's thought's on this?

Thanks!

 

[jap]

This question is relating to the poke-thru devices with the junction box on the end attached to conduit. I am wondering if that box needs to follow the same rules as other junction boxes in the NEC in that it needs to be accessible? It seems weird that these floor devices would require access right below them while floor-boxes with the conduit run in the slab don't need any sort of removability.

I looked online but I didn't see anything saying anything about this and I even checked a few product manuals. I have been making sure that there is enough space to get a ladder up to these, but a column of clearance is very inconvenient for the trades.

What are everyone's thought's on this?

Thanks!

They need to be accessible.

The difference is that a poke thru floorbox may have a splice in it's junction box, accessible from the bottom, whereas in a standard floorbox in the slab, the pipes come into the floorbox itself and, is accessible through the top.

Even if there wasn't a splice in the J-box, it'd be tough to pull the wiring through the J-box and up without access to it.

JAP>

 

[PD1972]

The poke-thru floor box junction boxes do need to be accessible. However, I would imagine that these junction boxes do not need an entire column of clearance nor will they even require the working space noted in 110.26(A) as these junction boxes will not likely require servicing/maintenance while energized. It's pretty common commercial practice for junction boxes above lay-in grid ceilings to be accessed by ladder so I am not sure what project specific circumstances are making you believe it is inconvenient for a tradesman to use a ladder.

Poke-throughs and floor boxes are typically selected based on application. I typically use poke-throughs in existing or new construction where there is access from the floor below (ie, installing poke-throughs on the second floor of a building with grid-ceilings on the first floor). In existing construction, this avoids the necessary cutting and restoration efforts associated with installing a new floor box and its associated conduits in existing slab. In new construction, this avoids coordinating floor box locations as the floors are being poured.

 

[jap]

The poke-thru floor box junction boxes do need to be accessible. However, I would imagine that these junction boxes do not need an entire column of clearance nor will they even require the working space noted in 110.26(A) as these junction boxes will not likely require servicing/maintenance while energized. It's pretty common commercial practice for junction boxes above lay-in grid ceilings to be accessed by ladder so I am not sure what project specific circumstances are making you believe it is inconvenient for a tradesman to use a ladder.

Poke-throughs and floor boxes are typically selected based on application. I typically use poke-throughs in existing or new construction where there is access from the floor below (ie, installing poke-throughs on the second floor of a building with grid-ceilings on the first floor). In existing construction, this avoids the necessary cutting and restoration efforts associated with installing a new floor box and its associated conduits in existing slab. In new construction, this avoids coordinating floor box locations as the floors are being poured.

And, speaking from field experience, where it get's interesting is when the different floors are occupied by different companies.

Having to go into a tenant space on the 1st floor and take apart their ceiling to service a poke-thru floorbox on the 2nd floor.

Been there more than once.

JAP>

 

[mwagner]

@jap, @PD1972, Thank you both for your replies.

It's pretty common commercial practice for junction boxes above lay-in grid ceilings to be accessed by ladder so I am not sure what project specific circumstances are making you believe it is inconvenient for a tradesman to use a ladder.

I don't think it's inconvenient to use a ladder when access to the box is accounted for. I coordinate these things using BIM and I always have to put some sort of an access column otherwise you wont even be able to see even it if you removed the whole ceiling because of the ductwork and piping. We also use them on existing buildings, but that is when real estate above the ceiling is a premium due to the constraints posed by the existing structure.

For the specific job I'm working on now, they are requesting floor receptacles in the room above a food service area where the hoods, ductwork, and concrete joists would make access impossible.

 

[PD1972]

... I always have to put some sort of an access column otherwise you wont even be able to see even it if you removed the whole ceiling because of the ductwork and piping. We also use them on existing buildings, but that is when real estate above the ceiling is a premium due to the constraints posed by the existing structure.

For the specific job I'm working on now, they are requesting floor receptacles in the room above a food service area where the hoods, ductwork, and concrete joists would make access impossible.

Specify a poke-thru device where the access junction box on the bottom is not attached to the bottom feed device. Poke-thru devices are available with just a bottom assembly where it is a trade size conduit stub with no box attached. The contractor would then be able to locate the junction box wherever they need to avoid conflicts with above ceiling ducts/pipes/etc. I think the Legrand Evolution series poke-thru devices has product data sheets that show you all the available bottom assembly options so look at those.

 

[mwagner]

Specify a poke-thru device where the access junction box on the bottom is not attached to the bottom feed device. Poke-thru devices are available with just a bottom assembly where it is a trade size conduit stub with no box attached.

I will look into that, thank you very much for the help!

 

[LarryFine]

For the specific job I'm working on now, they are requesting floor receptacles in the room above a food service area where the hoods, ductwork, and concrete joists would make access impossible.

If there is absolutely no access from below, you're left with notching and patching the floor for conduits.

 

[jap]

Regardless of the type of floor box, an electrician worth his salt will hard pipe it with no '"non-accessible" J-boxes in the run going to it.

Or at least the guys I work with do.

Tell us where you want it, and let us take it from there.

JAP>

 

[mwagner]

Thanks guys,

That's almost was what I was getting at. Floor-boxes are hard piped and don't require any access under the box so I was thinking if they just pulled through the box with no splice then it's basically the same thing as a hard pipe connection. I mistakenly thought that you cant hard pipe to the box directly, but if that's possible there's no issue. I've just never seen a picture of a poke-thru without the box below it haha.

 

[jap]

Thanks guys,

That's almost was what I was getting at. Floor-boxes are hard piped and don't require any access under the box so I was thinking if they just pulled through the box with no splice then it's basically the same thing as a hard pipe connection. I mistakenly thought that you cant hard pipe to the box directly, but if that's possible there's no issue. I've just never seen a picture of a poke-thru without the box below it haha.

It's not the same.

If the floor box is piped into the J-box from the side, or, flexed in where there is any angle at all in the wiring, (and there's those that will do that) it will be nearly impossible to service the wiring in the future.

The J-box on the end of the poke-thru is the issue.

Best to specify some other type of box, or, be very specific in your notes that the box must be piped in a way as to allow for installation and removal of future wiring.


JAP>

 

[jap]

On another note, if the hoods, ductwork, and concrete joists makes it impossible for them to access them as it is , they're not going to be able to access them to install them to begin with.


JAP>

 

[mwagner]

If the floor box is piped into the J-box from the side, or, flexed in where there is any angle at all in the wiring, (and there's those that will do that) it will be nearly impossible to service the wiring in the future.

I understand, that was my past argument and would have only applied to pulling straight through that box (if it applied which it doesn't). I will probably specify a poke-thru that can be hard piped.

On another note, if the hoods, ductwork, and concrete joists makes it impossible for them to access them as it is , they're not going to be able to access them to install them to begin with.

The ductwork and hoods are not there yet so the Electricians can install without issue. This was about being accessible after completion.

 

[jap]

I understand, that was my past argument and would have only applied to pulling straight through that box (if it applied which it doesn't). I will probably specify a poke-thru that can be hard piped.



The ductwork and hoods are not there yet so the Electricians can install without issue. This was about being accessible after completion.

You've got the burden of knowledge on that part of it.

We as installers can't control what gets in the way after we're gone.

JAP>