MC Install

[Alwayslearningelec]

Within an existing space that's gutten and getting completely renovated with drop ceiling do you more often attached MC cable to the ceiling pencil rod or other ceiling supports or install an independant support from ceiling above?

 

[LarryFine]

We're supposed to install our own supports, identified by red coloring, from support to grid, not swinging.

 

[CoolWill]

It depends on if anyone is looking.

 

[roger]

Is a ceiling contractor going to be installing new wires?

 

[nascaraddict20]

I am not a Journeyman. But I have seen MC whipped from box to box when in exposed ceiling.

 

[Alwayslearningelec]

We're supposed to install our own supports, identified by red coloring, from support to grid, not swinging.

I don't exactly follow.

 

[CoolWill]

I don't exactly follow.

He's saying that you have to provide ceiling wires that are independent of the wires that support the grid and your wires must be identified, commonly by painting them red or orange or green or whatever

 

[tortuga]

I don't exactly follow.

See 300.11

 

[LarryFine]

300.11 Securing and Supporting.
(A) Secured in Place. Raceways, cable assemblies, boxes, cabi‐
nets, and fittings shall be securely fastened in place.
(B) Wiring Systems Installed Above Suspended Ceilings.
Support wires that do not provide secure support shall not be
permitted as the sole support. Support wires and associated
fittings that provide secure support and that are installed in
addition to the ceiling grid support wires shall be permitted as
the sole support. Where independent support wires are used,
they shall be secured at both ends. Cables and raceways shall
not be supported by ceiling grids.

 

[electrofelon]

Within an existing space that's gutten and getting completely renovated with drop ceiling do you more often attached MC cable to the ceiling pencil rod or other ceiling supports or install an independant support from ceiling above?

I am not disputing what has been said about ceiling wires, but in my experience, I very rarely attach MC to ceiling wires, whether they be "my wires" or grid wires. I would rather staple to framing members, zip tie to a pipe/emt, or install a running board. Besides, for new work the grid and wires wont be there when you are doing most of your wiring.

 

[infinity]

Since he mentioned pencil rod so there are no ceiling wires. If the pencil rod is installed we use it but generally the majority of the cables are pulled before the lather is even on the job so the MC is supported on bridle rings.

 

[macmikeman]

The code says to not attach to grid ceiling wires. It doesn't say anything about hooking to the loop on the pin that supports the ceiling wire. That is what I often do using tie wraps. I agree that there is room to argue this, but I think I am on solid ground cause the support pins are not mentioned in the code book. Get er done.

 

[electrofelon]

The code says to not attach to grid ceiling wires. It doesn't say anything about hooking to the loop on the pin that supports the ceiling wire. That is what I often do using tie wraps. I agree that there is room to argue this, but I think I am on solid ground cause the support pins are not mentioned in the code book. Get er done.

Yeah I agree that should not be an issue. I got into an argument with an inspector about that once, I said what if I installed a half inch expansion bolt with a big forged eye bolt on it rated 20,000 lbs? At what point could that support the grid and my MC support?

 

[infinity]

It doesn't say anything about hooking to the loop on the pin that supports the ceiling wire.

I've never worked with support wires so can you explain how that doesn't that defeat the purpose of not allowing the weight of the cable to actually be supported by the same thing that is holding up the ceiling? From my understanding the support wires from their fastener down to the grid are part of a listed ceiling system that is not designed to support the additional weight of the cable so how is attaching to the loop any different than attaching to the wire?

 

[wwhitney]

The code says to not attach to grid ceiling wires.

Sorry, where exactly? I don't see that in the quoted section of 300.11(B).

Cheers, Wayne

 

[electrofelon]

Sorry, where exactly? I don't see that in the quoted section of 300.11(B).

Cheers, Wayne

Reading over 300.11(B) again, I don't have any idea what on Earth they are trying to say.

 

[mtnelect]

After the "Northridge Earthquake" happened, we were called to our Maintenance Contract properties to put everything back together. Not one "Ceiling Grid" survived ... all ended up on the floor !

January 17, 1994 ...

 

[Alwayslearningelec]

Since he mentioned pencil rod so there are no ceiling wires. If the pencil rod is installed we use it but generally the majority of the cables are pulled before the lather is even on the job so the MC is supported on bridle rings.

Bridle rings attached to slab/deck?

 

[infinity]

Bridle rings attached to slab/deck?

Yes. Either shot into the Q deck or the clipped to the steel beams. For poured concrete shot into the deck.

 

[mtnelect]

After the "Northridge Earthquake" happened, we were called to our Maintenance Contract properties to put everything back together. Not one "Ceiling Grid" survived ... all ended up on the floor !

January 17, 1994 ...

The only item that was left hanging, was the light fixtures.