FMC (greenfield) conduit

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bsh

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I have an application where I need to install 2 #12 control wires vertically in an existing building. The vertical distance is about 125 feet. The wires would be run in FMC conduit through an existing vertical chase. The chase only has access in the bottom and top. Per NEC 348.30(A) exception 1 there is no support distance requirement. Though allowed by the NEC it seems that the weight would be excessive. Has anyone ever had an application like this?
 
This looks like you may have to find an alternate method to shorten the vertical riser. Look at section 300.19 for maximum distance for support of conductors in vertical raceways. 18 AWG through 8 AWG 100' is the max between supports for conductors. And you will have a lot of stress on the fmc fittings as well .
 
If you're concerned about the weight you could rig it up with a messenger wire. Strap it to the messenger cable every few feet and lower it down the chase. Then you can support the messenger wire at the top and bottom.
 
infinity said:
If you're concerned about the weight you could rig it up with a messenger wire. Strap it to the messenger cable every few feet and lower it down the chase. Then you can support the messenger wire at the top and bottom.
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You still have to support the conductors per section 300.19.:smile:
 
Yea I had a to take a moment and think about the not allowing the mc. A bit odd but I'll go with it. I was digging the support wire part.

Can you talk about the not allowing the mc? What are the general lighting and rec's wired with?
 
mdshunk said:
I'd overlash some mule tape on it every few feet, and hang it at the top.
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Not a bad idea, a half hitch every so often would work pretty good.:smile:

I don't know he'll support the conductors though.
 
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