How best to provide flexible drops from drop ceiling.

[bjp_ne_elec]

Have a situation where a commercial facility need some flexibility out on the work floor. They have work benches but need them so they are not hard wired - like with a post coming out of the ceiling to feed them. One approach I thought of was to hang a box from ceiling and then drop SJ cord, using kellum grips. Does anyone else have any other approaches. I know lights in ceiling must be independently supported, not relying on the ceiling grid. What about the box? This building has bar joists that are about 6 feet above the ceiling and are difficult to get through, because it's tough to get a ladder in due to working through the drop ceiling.
Thanks

 

[iwire]

If I did cord drops I would secure them to the structure with 12 AWG steel tie wire. You should be able to push them up over the truss and tie both ends to the box.

Keep in mind a pendent (cord) supported box must have threaded hubs so you need at least a standard bell box but a better choice would be a malleable steel FS style box or a true pendent box. .http://www.woodheadsales.com/portable_outlet_boxes/multi-boxes_pendant_drops.htm

 

[masterinbama]

Use these


http://www.erico.com/products/LDwithLoop.asp



to support these.


http://www.erico.com/products/CADDYcfcIndSprtClps.asp


then hang an eye bolt to hang your kellum grip on.

 

[jumper]

Keep in mind a pendent (cord) supported box must have threaded hubs

It does not, that is just one such method allowed, alternatives acceptable to an AHJ and OSHA are allowed.

 

[iwire]

It does not, that is just one such method allowed, alternatives acceptable to an AHJ and OSHA are allowed.

Good luck with that.

314.23(H) Pendant Boxes. An enclosure supported by a pendant shall comply with 314.23(H)(1) or (H)(2).

(1) Flexible Cord. A box shall be supported from a mul-ticonductor cord or cable in an approved manner that pro-tects the conductors against strain, such as a strain-relief connector threaded into a box with a hub.

 

[Ponchik]

Good luck with that.

314.23(H) Pendant Boxes. An enclosure supported by a pendant shall comply with 314.23(H)(1) or (H)(2).

(1) Flexible Cord. A box shall be supported from a mul-ticonductor cord or cable in an approved manner that pro-tects the conductors against strain, such as a strain-relief connector threaded into a box with a hub.

Isn't the phrase such as a strain-relief connector threaded into a box with a hub. just giving you an example of such installation?


Besides can't he use a meyers hub on a 4S box?

 

[kwired]

Isn't the phrase such as a strain-relief connector threaded into a box with a hub. just giving you an example of such installation?


Besides can't he use a meyers hub on a 4S box?

What does use of a meyers hub add to the installation? You still have a locknut, probably one with a larger surface, but it is likely too large to fit in a 4S box so you would end up needing a standard locknut just to allow it to fit anyway.

 

[iwire]

Isn't the phrase such as a strain-relief connector threaded into a box with a hub. just giving you an example of such installation?

Yes.

That said I would fully expect OSHA or the AHJ to only accept a box with such a threaded hub, or a box specifically listed for pendent support.

Besides can't he use a meyers hub on a 4S box?

IMO that does not make a 'box with a threader hub' that makes a box with an meyers hub added.

Also you can fail with a 4S box by 110.3(B), they are designed to be mounted to a surface, not supported by the KOs.

 

[jusme123]

Yes.

That said I would fully expect OSHA or the AHJ to only accept a box with such a threaded hub, or a box specifically listed for pendent support.

IMO that does not make a 'box with a threader hub' that makes a box with an meyers hub added.

Also you can fail with a 4S box by 110.3(B), they are designed to be mounted to a surface, not supported by the KOs.

IMO, "such as a strain-relief connector threaded into a box with a hub" does not make a threaded hub a requirement.

 

[iwire]

IMO, "such as a strain-relief connector threaded into a box with a hub" does not make a threaded hub a requirement.

And you are right.

Good luck with that and OSHA.

 

[jumper]

Good luck with that.

Of course, I am not bright enough to come up with alternative methods, but the CMP stated that the intent and wording is to allow them and that is why they have rejected proposals specifically requiring a threaded hub.

 

[Dennis Alwon]

Have a situation where a commercial facility need some flexibility out on the work floor. They have work benches but need them so they are not hard wired - like with a post coming out of the ceiling to feed them. One approach I thought of was to hang a box from ceiling and then drop SJ cord, using kellum grips. Does anyone else have any other approaches. I know lights in ceiling must be independently supported, not relying on the ceiling grid. What about the box? This building has bar joists that are about 6 feet above the ceiling and are difficult to get through, because it's tough to get a ladder in due to working through the drop ceiling.
Thanks

Wow-- I haven't heard from you in years-- hope all is well.

 

[renosteinke]

I was told once of a ship that had taken a missile hit, was on fire, and flooding. A sailor pulled himself from the burning compartment, only to be chastised for being 'out of uniform.'

Such is happening here. All this focus on the box at the end of the cord - when that's the least of the issues. Nor will that code citation help where you need to address your concerns - to the top end of the install!

Such drops used to be easy - hang a 4S from building iron, hang a Kellems grip from the hard ceiling directly above the drop, and punch a hole in the ceiling tile to let the cord pass. We can't do that now, because we are not allowed to have the flexible cord above the ceiling.

There are various brackets for mounting stuff to the grid, but IMO they're not up to the loads that this application would provide. Ceiling grids are not made to carry 'live' loads.

The best I can figure is that you make a 'tile' out of (at least 1/2") plywood, and support that as you would a light troffer. Run flex or MC to an "old work" box you mount to the board. Modify a 4S blank cover so you can attach it to the box, and attach your cord grip to the modified cover.

If you also cover the face of the plywood with FRP, it'll look a lot nicer. You can paint the 4S cover with 'appliance enamel' or 'spray lacquer' for a particularly nice finish.

Now ... for that pesky 'free hanging' end .... We have none other than our Joe T to thank for the code section, for he spent the better part of a decade showing pictures of used, abused, and damaged 4S boxes on the ends of extension cords. His crusade also led directly to two other code requirements- that devices be attached with two screws on 'industrial' covers and that the covers have flat corners for 'better' grounding at the attachment points.

The code section does not require the use of a box at all - a free hanging connector would be compliant. A purpose-made receptacle assembly with a clamp would comply; Woods makes just such a thing. You could even have the cable go directly into a fitting on a machine.