i have an EMT question

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crwsanfran

Member
i need to install a section of 3/4 inch emt from a beam in a warehouse about 20 feet hight straigt down to a controll box that is directly below it. There is nothing to attach the emt to other than the beam above. The emt is going to be used for low voltage data cabling.

thanks for your help in advance

[ December 12, 2003, 04:29 PM: Message edited by: crwsanfran ]
 
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jimwalker

Senior Member
Location
TAMPA FLORIDA
Re: i have an EMT question

It's poor workmanship but i think it's legal.Would be sure the AHJ doesn't have any control over L V
What's going to keep this from snapping in 2
 
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crwsanfran

Member
Re: i have an EMT question

thats my delima there is nothing to support this emt from the warehouse ceiling beam down to the cortoll box.
 
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gregoryelectricinc

Senior Member
Re: i have an EMT question

Maybe a little bit of overkill but how about adding a 20' length of Uni-strut along with your EMT. Should provide a fairly rigid support?
 
russ

russ

Senior Member
Location
Burbank IL
Re: i have an EMT question

I don't see EMT(358.30) being legal, I think you will have to install RMC (344.30(B)(3).

Russ
 
tonyi

tonyi

Senior Member
Re: i have an EMT question

RMC/IMC is the only thing I know of that can do a 20' unsupported verticle run...
 
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hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
Re: i have an EMT question

I've done this using chain or cable secured at the top to the structure. And I have seen a run of uni-strut used for this purpose. Then use one hole clamps with a bolt for the chain or a cable clamp for cable. A lot of those big sell all warehouse places use this for there cash register stations.
 
M

moorepower

Member
Re: i have an EMT question

In this case I have used seal tight with strain releaf. At the end i used a weather proof box, this way there are no knock outs and these box handel abuse better.

Moorepower Lebanon, ohio
 
D

d and o

Member
Re: i have an EMT question

I'd recommend strain relief at both ends.
Also consider the conductors in the Liquid tight, they would require some strain relief as well.
 
K

karen

Member
Re: i have an EMT question

I think you should make a power pole type arrangement, such as is used in department stores for his type of vertical run. Is this in an exposed area where it will be seen? If not unistrut will probably do.
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Re: i have an EMT question

What would have been the problem with using Intermediate rigid conduit?

There are plenty of quality compression or set screw fittings that are available, for those that do not have threading equipment.

Use the factory threaded ends at the mid span couplings and use a non threaded type connector at one end or the other.

342.30(3)
Exposed vertical risers from industrial machinery or fixed equipment shall be permitted to be supported at intervals not exceeding 6 m (20 ft), if the conduit is made up with threaded couplings, the conduit is firmly supported at the top and bottom of the riser, and no other means of intermediate support is readily available.
Click to expand...
Or as has been said use uni-strut, it is not expensive or hard to work with, you can even get it in 20' lengths if you want.

The use of "sealtight" for this application is not allowed, :roll:

350.30(A) Securely Fastened.
LFMC shall be securely fastened in place by an approved means within 300 mm (12 in.) of each box, cabinet, conduit body, or other conduit termination and shall be supported and secured at intervals not to exceed 1.4 m (41/2 ft).
Click to expand...
At this point as the LFMC is already run why not run uni-strut beside it and properly secure to that?

[ December 13, 2003, 08:42 AM: Message edited by: iwire ]
 
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d and o

Member
Re: i have an EMT question

Well I haven't looked at Art 350 (obviously), , but I'd guess it covers the installation of LFMC, regardless of the wire type.

[ December 17, 2003, 06:50 PM: Message edited by: d and o ]
 
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pierre

Senior Member
Location
Westchester County, New York
Re: i have an EMT question

Conductor support is covered in 300.19 and the minimum distance in the table is 35 feet. At 20 or so feet, there is no requirement for supporting the conductors in the raceway.

Pierre
 
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jimwalker

Senior Member
Location
TAMPA FLORIDA
Re: i have an EMT question

Seen this cure in a WALLYWORLD garden center
2 x 3 aluminum from ceiling to cash register.
They could run MC and register/computer
Looked real nice
 
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d and o

Member
Re: i have an EMT question

well let's see, the MCC would have to be supported at proper intervals or where's that UL listing for the assembly of the 2x3 aluminum as a raceway?

:confused:
 
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