Question received by e-mail:

I would say it's possible to install 3/4" EMT in bar joist and secure it with plastic tyrap material. A lot would depend on the size of the tyraps and the frequency of the tying. There is not much in the NEC about this so the judgment of the inspector kicks in.

A bar joist as in: http://www.intelicad.com/Joist.jpg

358.30 A - EMT shall be securly fastened in place.... Seems like an inspector could have a difference of opinion on that.

Are nylon tie wraps UL approved for such use? Fire rating, etc...?

Why not use the caddy's? http://www.erico.com/public/images_thm/products/FF-Electrical/NorthAmerica/0319.jpg

This leads me to the next logical question. How about mc cable? What is the opinion of the minds here about strapping mc with tie wraps?. Just curious, because I am currently doing a job that way and haven't called in for rough inspection yet.

I don't see why not, and have done it a few times. Only in a pinch.... Not in an exposed cieling though. I would also metion that certain types are not rated for prolonged exposure to sunlight. And would fail over time.


Normally I use metal tie wire.

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

Interesting how the code directly specifies the use of tie wraps as being ok and it doesnt'for EMT. EMT needs to be installed more securely anyway b/c of pulling the wire through and adding circuits, etc...,



[This message has been edited by GalwayElectric (edited 06-03-2006).]

For what it is worth the supports for EMT and conduit are not generally required to be listed. If they where strut products are a violation as they are not listed.

Most Caddy type products are listed for 'positioning only' whatever that means.

[This message has been edited by iwire (edited 06-03-2006).]

As above tywraps are legal for MC. As to EMT, as there is no references yay or nay, the AHJ has the 'gray area' to determine. Above a drop ceiling? On bar joists?

IF it's a plenum ceiling, the ty-wraps require 'plenum' rating (if plastic mat'l)

My gut call? Adequate spacing...adequate support..OK. But remember, my gut call!

John

I always interpreted that as meaning they were OK for holding conduit etc. in place, but not for "dynamic load" type applications. i.e I wouldn't use them as part of an overhead lifting setup or whatever...