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SS396 10-14-2007 09:26 AM

painted emt conduit
 
I have a block garage with bare unfinished walls. All wiring is within conduit. I want to spray paint the walls. Is it ok to paint over the conduit and electrical boxes? Thank you.

J. V. 10-14-2007 09:36 AM

Yes you can. If you look at some of the new restaurants and big box stores, all the conduit and boxes are painted black along with everything else in the open ceiling. It a non issue.

tom25 10-17-2007 11:27 AM

I agree for the garage outlet, but disagree with the box stores and restaraunts, based on the tests that we have performed.
The NEC should address this issue with additional de-rating for
commercial/ industrial buildings.

frenchelectrican 10-17-2007 12:22 PM

Quote:

Originally Posted by tom25 (Post 68587)
I agree for the garage outlet, but disagree with the box stores and restaraunts, based on the tests that we have performed.
The NEC should address this issue with additional de-rating for
commercial/ industrial buildings.


May i ask why you have issue with this ??

The NEC code do address pretty well on commercal / Industrail area

majorty of them i did see not only on box store and few other place do paint the conduct some do paint it for indenftion like fire alarm , data cables , few other as well.

with properly prepped EMT's, Intermate conducts , Rigid metalic conduct they have no issuse with painting over at all.

Merci, Marc

tom25 10-19-2007 01:50 PM

The problem is with the heat being able to disapate from the conductors.
When a conduit is painted white, the white paint acts as an insulator, and does not allow the heat disapate.
Conduit that is painted black will operate cooler than one that is not painted
due to the black paint acting as a heat sink and wicking the heat from the pipe.
My issue is that the paint makes a big difference, and there should be additional de-rating factors for commercial / industrial applications when the raceways are painted.

Andy in ATL 10-19-2007 02:53 PM

Quote:

Originally Posted by tom25 (Post 68963)
The problem is with the heat being able to disapate from the conductors.
When a conduit is painted white, the white paint acts as an insulator, and does not allow the heat disapate.
Conduit that is painted black will operate cooler than one that is not painted
due to the black paint acting as a heat sink and wicking the heat from the pipe.
My issue is that the paint makes a big difference, and there should be additional de-rating factors for commercial / industrial applications when the raceways are painted.

Do you have proof to back this up???:huh:

HouseHelper 10-19-2007 03:05 PM

Quote:

Originally Posted by tom25 (Post 68963)
The problem is with the heat being able to disapate from the conductors.
When a conduit is painted white, the white paint acts as an insulator, and does not allow the heat disapate.
Conduit that is painted black will operate cooler than one that is not painted
due to the black paint acting as a heat sink and wicking the heat from the pipe.
My issue is that the paint makes a big difference, and there should be additional de-rating factors for commercial / industrial applications when the raceways are painted.

HUH??

Stubbie 10-19-2007 03:28 PM

Who are "we"? If you have made tests please tell us who you are....

Cole 10-19-2007 03:38 PM

I would like to know as well.

Pretty interested observation you have there.

tom25 10-19-2007 03:51 PM

I invented a support system for cables that is UL listed, and prior to sending it to UL for testing we tested it ourselves for impact, and temperature.
While we were set up for the tests for our product we did a lot of comparison testing of other products.
I have been in the industry for quite some time, and always wondered about the impact of paint on emt, so we tested that as well.

Andy in ATL 10-19-2007 03:59 PM

cool, ......show test results and then submit a change proposal for the 2011 NEC.:) But I really wanna see the results... Then maybe I can submit the proposal and have my name put up in lights and all the women will adore me!!:jester: :yes:

Stubbie 10-19-2007 04:57 PM

Hey thats fine and I don't doubt your opinion but it is only an opinion unless you have conclusive proof that is broadly accepted by the conduit makers and the NEC who would then have to get their ducks in a row and say you can't paint the conduit in the product specifications and characteristics code articles.

This is really going to take some doing because they have extensively tested conduits for effects as to derating in about every imaginable configuration. I don't know about paint though.

Problem I see are there are literally and physically thousands of miles of painted conduit in the commercial world and this is the first time I have ever heard that it is a concern. I have never heard of a failure to conductors due to heat rise because a conduit was painted....btw neither has the NFPA.

At any rate new issues are discovered all the time so best of luck with your belief and test results on this painted conduit issue.

EDIT:

I found what I was looking for.....just so you don't think I'm blowing off your stance on painted conduit there is reason to consider this and to pursue its relevancy......look here....

http://www.iaei.org/subscriber/magaz...a/lindsey.html

Andy in ATL 10-19-2007 06:35 PM

Hey guys... It doesn't take a brain surgeon to figure that if you paint RMC black and put it on an Atlanta rooftop it might get warmer than if it was unpainted. I'm talking blacked out ceilings in air conditioned showrooms and white conduit down at the local wallyworld, also airconditioned. I'd love to see the test results on these conduits in a controlled environment...say 86 deg. F.

tom25 10-22-2007 11:42 AM

We maintained an ambient between 70 / 75 degrees F. The reason I wanted to do the test was because we have wired night clubs, and other buildings with painted EMT.
None of the NM cable manufacturers have ever tested their cables with out de-rating them either.
That is what we did to find out at what point they would over heat when they were installed together to simulate bored holes.
It was really interesting.:thumbup:

J. V. 10-22-2007 11:48 AM

Some people just have way to much time on there hands.


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