EMT vs. ENT

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jkim780

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I have an electrical contractor who is trying to replace EMT conduits to ENT where walls are all blocks. This has been brought up to an achitect during the value engineering.

What would be the advantage of EMT over ENT? I mean, can you use ENT where you normall use EMT?

It seems to me that it would be ok per 362 but I am not sure what's good or what's bad. Never used ENT before. Is it permitted in those areas? Have you guys used ENT conduit a lot in stead of EMT?
 
Re: EMT vs. ENT

Speaking just for myself, I am not sure there is anything "wrong" with this idea. I would want more information though.

Is this part of a poured wall? If so, it may not be allowed by other codes. I seem to recall you can't install it as part of the pour.

Or that could be some old spec still rattling around in my head from 15 years ago.

<added> just realized after I hit send that you said "block", so there would be no pour.

[ February 09, 2005, 03:27 PM: Message edited by: petersonra ]
 
Re: EMT vs. ENT

Do you mean substitute EMT for RNC, or really ENT.

The differences between EMT and ENT are numerous.
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Ron,

Really ENT. What would be the numerous differences?

I would want more information though.
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petersonra,

Walls are all blocks and ceiling will be drop-in ceiling. Would it make any differences if the wall was a drywall?
 
Re: EMT vs. ENT

A few include that it is flexible and doesn't provide the level of mechanical protection that EMT does. EMT offers some additional level of equipment grounding with a dedicated equipment ground conductor, although not required for EMT.
Some limitations with regard to the size of the building that it is permitted.
 
Re: EMT vs. ENT

why would someone use it over PVC conduit? is it that much cheaper?

we are talking about the thin plastic stuff, not the corrugated stuff right?
 
Re: EMT vs. ENT

Ron,

All phase conductors run with an equipment ground conductor, so grounding wouldn't be a problem. Since it is installed in block walls, I think that will give us the level of mechanical protection that we need.

Some limitations with regard to the size of the building that it is permitted.
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Can you elaborate it, ron? Is it NEC or local code?

petersonra,

I am talking about ENT(Electrical nonmetallic tubing)which is a nonmetallic pliable corrugated raceway. And I believe ENT is made of smae material (PVC) used for rigid nonmetallic conduits.

According to the E.C., it is cheaper in price and it is also easy to install. So, we could save significant money out of it.

So, is it fair to say that we can use ENT in places where we normally use EMT unless local code prohibits it?

[ February 09, 2005, 05:16 PM: Message edited by: jkim780 ]
 
Re: EMT vs. ENT

Lots of caveats to the 3 story height limit. You can still use it behind 15 min. thermal barriers. And you don't even need that for within walls , floors, and ceilings if the building is completely sprinklered. See your code book for all the details and exceptions ect.

ENT is not allowed where exposed to damage, unless protected from damage. Temp. limit of 122 deg F, not in hazardous locations, not used for the support of luminaries, etc. One problem with ENT is that it will produce toxic gas when it burns (like PVC).

I wonder if 362.30 applies when installing it in block? How would they secure it inside a block wall?

Steve
 
Re: EMT vs. ENT

The building is fully sprinkled, so I don't think 15 min. thermal barriers are needed.
I wonder if 362.30 applies when installing it in block? How would they secure it inside a block wall?
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Very good point, steve. I was thinking of that, too. As a matter of fact, I was going to ask that same question to E.C., but I asked myself how would it be different from securing EMT conduits inside a blok wall? Only difference is 10ft vs. 3ft.
 
Re: EMT vs. ENT

Companies I have worked for have used E.N.T. in block walls. I would agree with the G.C. I would also use Rigid sch. 40 or 80. Also buy a bucket of K.F.C. for the brick layers,then you won't find no mortar in your pipes. :p
 
Re: EMT vs. ENT

when they pour the concrete down inside the block walls, and it hardens, the conduit will be supported
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Being an engineer, they don't let me out of the office very often. (Just in case this comment seems naive).

What part of laying a block wall includes pouring concrete into the block??? I thought they just troweled it on between layers?


Eye-zak: I'd like to play poker with your member number. 4 aces!!!
 
Re: EMT vs. ENT

Originally posted by steve66:
What part of laying a block wall includes pouring concrete into the block??? I thought they just troweled it on between layers?
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Steve I would call that unusual too, at least in my area.

I have seen entire block walls filled with 'vermiculite' (sp?) a type of thermal insulation.

I have seen entire block walls filled with sand for sound deadening.

It is also normal for one vertical cell in the blocks to have rebar installed and filled with concrete every 'X' amount of feet for strength. It is also typical to have a horizontal layer of special blocks that have a 'V' notch through the inside to lay rebar in and then filled with cement for strength.

I have never seen an entire block wall filled with cement. At that point I would think it would be more cost effective to just use forms and pour a solid concrete wall.
 
Re: EMT vs. ENT

Iwire:

Do you think the sand helped any with the sound? I am working on a design for a building with all block walls. That's why this thread intrested me. I am considering changing the prints to allow ENT inside the block walls. Some of the walls in this job are thinner, 6" block instead of the standard 8". I think it may be a pain to get EMT into those walls.

Steve
 
Re: EMT vs. ENT

Steve the job I saw the sand filled block walls was a movie theater and they filled the walls separating one theater from another.

I do not know if it was effective. I was told it helped but most sound deadening methods I see try to isolate one layer of building matrial from the other, the sand seems to do the opposite. :)

The sand did seem to help when there was an extremely hot fire (fed by propane tanks for temp heat and the storage of building materials) burning in one of the theaters for many hours but it did not effect the carpet glued to the blocks on the adjacent theaters. :D
 
Re: EMT vs. ENT

Did a couple compressor room where we poured Vermiculite into the blocks for sound deadening. Worked real well for keeping the sound and heat in.
 
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