MC cable Support

[cvirgil467]

Is tie-wire an approved method of supporting MC cable per 330.30 of the 2005 NEC?

Thanks.
C

 

[mdshunk]

Does tie wire support the MC? If the answer is "yes", you already have your answer.

 

[infinity]

I would say maybe. Here's the requirement:

330.30 Securing and Supporting.
(A) General. Type MC cable shall be supported and secured by staples, cable ties, straps, hangers, or similar fittings or other approved means designed and installed so as not to damage the cable.

Tie wire is not a fitting but it may be an approved means depending on who you ask. For what it's worth it's much stronger than a cable tie which is an approved means.

 

[GilbeSpark]

I've got nothing to back this up but someone mentioned to me that you can't use bare tie wire because they're "dissimilar metals", which doesn't make sense because CJ's are also a different metal than the aluminum on the MC. Is there anything in the code supporting this?

 

[Buck Parrish]

If you are hanging the mc cable from it . I would say no. If the bottom is attached and you use a caddy bat wing strap, then yes it's good. The wire must be identified that it is yours and not to hold the cieling up.


I was thinking cieling wire.
Tie wire I'm not sure about

 

[mdshunk]

I've got nothing to back this up but someone mentioned to me that you can't use bare tie wire because they're "dissimilar metals", which doesn't make sense because CJ's are also a different metal than the aluminum on the MC. Is there anything in the code supporting this?

Think back and try to remember all the aluminium straps or supports you've ever used with MC. I can't really think of any, myself.

There goes that theory.

 

[mdshunk]

If you are hanging the mc cable from it . I would say no. If the bottom is attached and you use a caddy bat wing strap, then yes it's good. The wire must be identified that it is yours and not to hold the cieling up.

Okay, prove it! Sounds like some wacky local rule.

 

[infinity]

I've got nothing to back this up but someone mentioned to me that you can't use bare tie wire because they're "dissimilar metals", which doesn't make sense because CJ's are also a different metal than the aluminum on the MC. Is there anything in the code supporting this?

IMO the dissimlar metal argument is false because of the things you've mentioned.

 

[peter d]

Think back and try to remember all the aluminium straps or supports you've ever used with MC. I can't really think of any, myself.

There goes that theory.

Or steel MC connectors.

Tie wire is fine. Let's not over think this one, shall we?

 

[mdshunk]

Tie wire is fine. Let's not over think this one, shall we?

Right. If tie wire does the job, I'm not sure why people want to find something wrong with it. I guess because it's cheap?

 

[Buck Parrish]

Okay, prove it! Sounds like some wacky local rule.

Which part?

 

[peter d]

Right. If tie wire does the job, I'm not sure why people want to find something wrong with it. I guess because it's cheap?

Or the infamous "listing" issue.

 

[mdshunk]

Which part?

The part about you must use a batwing on a wire.

 

[Buck Parrish]

The part about you must use a batwing on a wire.

I was thinking cieling grid wire.
But I don't think you could use tie wire to support to the cieling grid wire.
Like you said it's cheap. Caddy wants their share of the $.

 

[mdshunk]

Here's what I've done in the past. Hang a bunch of lengths of my blue or wathever color tie wire before the grid goes in. When I run my MC's, I'll wrap each one with a single wrap of the tie wire where necessary. When more than one MC is involved, they're lined up under each other so they're not bundled. When all the MC is run, and the grid is in, I'll wrap the bottom of my tire wires in the grid someplace to secure the tail end and trim it off. No batwings anywhere. Those things are handy sometimes, but they're 11 cents a piece.

 

[Buck Parrish]

Here's what I've done in the past. Hang a bunch of lengths of my blue or wathever color tie wire before the grid goes in. When I run my MC's, I'll wrap each one with a single wrap of the tie wire where necessary. When more than one MC is involved, they're lined up under each other so they're not bundled. When all the MC is run, and the grid is in, I'll wrap the bottom of my tire wires in the grid someplace to secure the tail end and trim it off. No batwings anywhere. Those things are handy sometimes, but they're 11 cents a piece.

Are you talking tie wire like is used for rebar. Or the heavier cieling grid wire.
And what do you use to support your lights.

 

[peter d]

Ceiling grid wire and tie wire are two completely different animals. I believe that tie wire is in view here.

 

[mdshunk]

Are you talking tie wire like is used for rebar. Or the heavier cieling grid wire.

Yes, just tie wire. Why would it matter? It's not like the MC is going to fall down. I could use a good stout string if I was so inclined.

I don't use tie wire of any sort for my lights. It's not required unless you have special rules, but that's another thread.

 

[Buck Parrish]

Yes, just tie wire. Why would it matter? It's not like the MC is going to fall down. I could use a good stout string if I was so inclined.

I don't use tie wire of any sort for my lights. It's not required unless you have special rules, but that's another thread.

They are more strict down here. We even have state issued license:wink:

 

[mdshunk]

They are more strict down here. We even have state issued license:wink:

Has nothing to do with that.

Tie wire is not prohibited for MC support, no matter where your license if from, unless you have more specific rules.

Tie wire is not required on lights if the grid is rated for support (just flip out the clips on the fixture), unless you have extra rules.

Roll that up in your license and smoke it.