Support of MC cable above suspended cieling

[craig127]

I was failed on an above ceiling inspection because I supported mc cable on the ceiling grid wire
300.11.2 Exception allows this in a non fire rated ceiling as long as it is installed per the manufacture's instructions.
Here's the tricky part...According to the manufacture they do not have instructions for installing lighting whips. As long as the lighting whips do not interfere with the grid being level and square and the cable is not resting on the grid the manufacture has no interest in how you install or support them. They defer to ASTM 636c which only stats you can not bend the grid wire to level the ceiling when installing the ceiling grid.
The inspector wants individual wire supports hung from the structure and tied off to the grid to support the MC cable. I dont believe I need to do that
300.11 is vague, 300.11.2 is very clear as is the exception...Any thoughts would be appreciated

 

[jimthesparks]

I would have to side with the inspector on this one. IMO since there is no manufacturer instructions on how to do this it would not be allowed.

 

[roger]

300.11.2 Exception allows this in a non fire rated ceiling as long as it is installed per the manufacture's instructions.
Here's the tricky part...According to the manufacture they do not have instructions for installing lighting whips.

Seems pretty cut and dry, if the manufacturer has no instructions for how to do it then you can not provide back up for your installation and the inspector is correct.

Roger

 

[Dennis Alwon]

How long are the whips. If these are from the manufacturer they are generally 6' long and do not need support.

 

[MarkyMarkNC]

Inspector is correct, I believe.

That was probably my least favorite code change of all time. 1996 was it? I used to be a bat wing clipping maniac.

 

[craig127]

Roger,
If I have no back up from the manufacture neither does he so he has basis to fail me; I am not in violation of the manufacture's recommended installation they have nothing to say it isn?t allowed without an approved method from the manufacture it would have to fall back on 330.30 for support.....I would think

Dennis,
The whips in this case are less than 6 feet so I am going to argue 330.30-D-2 and see if I just cut em lose if he will let that fly

 

[jaylectricity]

Roger,

The whips in this case are less than 6 feet so I am going to argue 330.30-D-2 and see if I just cut em lose if he will let that fly

I would love to see the look on his face. "So, did you get these independently supported?" *looks up at dangling wires* "Is this some kind of joke?"

You: "Nope...turns out they don't even need to be supported so I cut 'em free!"

 

[Dennis Alwon]

I would love to see the look on his face. "So, did you get these independently supported?" *looks up at dangling wires* "Is this some kind of joke?"

You: "Nope...turns out they don't even need to be supported so I cut 'em free!"

I have never supported a 6' whip. No reason to do it. Of course if you do support it then it must not be on the grid wires.

 

[cadpoint]

In NC... to the OP


That would be a fault for a long time around here... but with some little moderations through the cycles now to have come to this point... as I recall.

Self supported individual wire for the MC or some sort of individual support of a wire are all the norm now.

 

[jaylectricity]

I have never supported a 6' whip. No reason to do it. Of course if you do support it then it must not be on the grid wires.

That's the ridiculousness of the NEC.

Although...I suppose...

With a whip that short it might not be a great idea to have it too secured. Ya know, to keep the fixtures and tiles flexible.

 

[Finite10]

If the inspector is interpretting the thrust of 300.11 he may be willing to dig heels in;

300.11 closes with... 'Cables and raceways shall not be supported by ceiling grids'.
Both (1) and (2) following that have the same inent ...'shall not be secured to, or supported by, the ceiling assembly, including ceiling support wires.'

To get around it you have to have (1) the combined system tested, or (2) have the ceiling manufacturer checking his insurance policy. You may not be seeing a notice prohibiting it because the manufacturer doesn't need to give notice, but it seems to me that hanging electrical off the ceiling system needs to be expressly OK with the manufacturer.

To hang MC and flex off the connector to the luminair unsupported is OK but it can't lay on the grid - that's my take anyway. Some coil excess whip on the fixture - that's OK until someone dumps it off the fixture right before the inspector arrives.

 

[curt swartz]

Don't you have independent wires supporting your fixtures? If so clip the wires to them.

 

[ActionDave]

Don't you have independent wires supporting your fixtures?....

Depends on where you work. That is a building code requirement.

 

[craig127]

here is the responce from the manufacture:

Hi Craig,
We do not have anything in writing to address the NEC issue. Best suggestion is that if the wire or cable rests on the grid:
1.) It must not rest on or deflect onto the ceiling panels
: 2.) Total the weight of all elements supported by grid, i.e. ceiling panels, lights, diffusers, the cables and wiring, etc., cannot exceed the load capacity of the grid. Would need to determine the weight of all these elements to make sure they are not overloading the grid. We can supply load info on any of our Suspension Systems per your request.
3.) Caddy Fasteners (800 252 2339) also makes some independent support clips that can be used to keep wires and cables off the grid.
Per our installation department, Armstrong does not interpret codes as to what is acceptable. Any attachment to the hanger wires must be done in a manner that does not affect the levelness or squareness of the ceiling installation. Our installation instructions refer to ASTM C 636 which in section 2.3.3 states that local kinks and bends shall not be made in the hanger wires as a means of leveling carrying channels.

Lisa M. Bowman CSI, CDT
ABP Technical Consultant

All they seem to care about is keeping the cable off the grid...

 

[Dennis Alwon]

To hang MC and flex off the connector to the luminair unsupported is OK but it can't lay on the grid - that's my take anyway.

Yet 330.30 specifically allows mc unsupported up to 6' when used as a connection to a light in a ceiling that is accessible. So how do you do that without laying it on the fixture or tile or grid?

 

[craig127]

With no recommendations fore or against from the manufacture on cable installation the exception can not be used or excluded So in this case we have agreed to disagree. I have passed the final inspection with the condition that we will use the accepted practice in that city of not using the grid wire for support of fixture whips in the future.

 

[Sierrasparky]

it seems like you would even need support for the fixture unless you can prove the weight is within the limits of the grid.

 

[roger]

Yet 330.30 specifically allows mc unsupported up to 6' when used as a connection to a light in a ceiling that is accessible. So how do you do that without laying it on the fixture or tile or grid?

Dennis, that would only come into play if the ceiling manufacturer allows for the ceiling to support the wiring otherwise, 320.30 and 330.30 can only be used in the first two examples below and then the cable assemblies would have to rest on the fixture IMO

Roger

 

[craig127]

that looks to me like it violates 300.11A. the MC is resting on the grid between the last 2 fixtures

 

[roger]

that looks to me like it violates 300.11A. the MC is resting on the grid between the last 2 fixtures

The ceiling in the illustration has documentation that states it can support the weight of the wiring.

Roger