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Subject - Conduit outside
David Hyatt When running EMT on an exterior wall where subject to rain, does the code require spacing off wall or can it be strapped to wall. Something is in the back of my mind in damp or wet locations it has to be spaced? Code Ref? I found where indoor wet locations have to be spaced off wall 1/4" maybe that is what I was thinking about.
Also, EMT on outside rusts, is this even a good practice to use EMT outside?
JimmyDee 358.6 Listing Requirements.
EMT, factory elbows, and associated fittings shall be listed.
II. Installation
358.10 Uses Permitted.
(A) Exposed and Concealed. The use of EMT shall be permitted for both exposed and concealed work.
(B) Corrosion Protection. Ferrous or nonferrous EMT, elbows, couplings, and fittings shall be permitted to be installed in concrete, in direct contact with the earth, or in areas subject to severe corrosive influences where protected by corrosion protection and judged suitable for the condition.
(C) Wet Locations. All supports, bolts, straps, screws, and so forth shall be of corrosion-resistant materials or protected against corrosion by corrosion-resistant materials.
That should answer your question.
Jim
Dave Nix Hi David,

What Jimmy said plus;
No. You do not need the space on an exterior install.
David Hyatt What would be corrosion resistance materials consist of? There is only one type of EMT, right? What keeps it from rusting?
JimmyDee
quote:
Originally posted by David Hyatt

What would be corrosion resistance materials consist of? There is only one type of EMT, right?

I've seen and used a EMT that was actually galvanized. No inch marking or lines on it and it seems to hold up fairly good. Corrosion resistance materials have some type of plating on them and I think most that you would buy would fit in this category.
Jim
cs The 1/4" requirement you are thinking of applies only to indoor wet locations. 300-6c
Ryan_J It also must be "arranged to drain". See 225.22
frenchelectrician this is common trouble with the EMT conducts as well for other types

it should pitch very slightly for drainage on outside area and inside area where the tempture differntal is pretty high too should do the same way too.

Ryan: i dont know about the code say something about the box like 3R type. correct me if i am wrong here like wp boxes shold have some kind of drainage opening to get water and moisture out ?? i did see alot of wp box dont have some type of drain opening at all.
let me know about that one ryan.

merci , marc
Ryan_J Good morning Marc. The only I can see so far is 314.15(A), which says the boxes outdoors shall be installed so as to prevent moisture from entering or accumulating in the box.

I'll try to look a bit more over the weekend and see if I can find something else for you :)
earlydean NFPA's Jeff Sargent tells me to drill a small (1/8 inch) hole in conduit bodies at strategic locations for drainage. If a conduit is outdoors, it will accumulate moisture. Conductors installed in outdoor conduits are required to be water proof too. There must be a route for the water to get out. When running rigid galvanized outside, drains are required to be installed at low points for this purpose. Explosion proof, too.
iwire
quote:
Originally posted by David Hyatt

Also, EMT on outside rusts, is this even a good practice to use EMT outside?


In my opinion no it is not good practice to use it outside.

It is allowed and may work fine in some areas of the country but here in New England it rusts out badly.

Most of the jobs I work on will not allow EMT for any outside use, they will requirer IMC or RMC for all exposed outside work.

This is an engineering specification, not a a NEC rule.
Scott Vickrey In central Texas galvanized EMT is run on the out sides of buildings using rain-tight fittings all the time. I have done remodels where we take down old EMT and it is still in good shape. I don't know about the coastal areas though. I now live in West Texas and we just don't get enough rain to worry about it. It only averages 16" a year and you should be here the day it does it.
iwire I hear you Scott, I imagine there are many areas where the climate would not bother EMT.

That's why I tried to make clear it was an opinion not code.

Here the worst application is on roofs for roof top equipment, often I find sections missing with just the exposed conductors continuing, hopefully including a grounding conductor.

I am guessing this is from being buried in snow a few times a year.
renosteinke The 1/4 spacing requirement is found in USDA requirements for food processing areas that are subject to washdown- not the NEC at all.
Water may enter no matter what. Corrosion may or may not be an issue. NEC (300.6) requires that raceways be "suitable;" so local experience can result in a regional difference of opinion.
One common local requirement is to require EMT that is subject to being disturbed (such as acroos a rooftop) to have a green wire, and not to rely upon the EMT alone for grounding.
KSsparky Reno: Have a look at 2002 NEC 300.6(C), it does have the 1/4" requirement for indoor wet locations.
renosteinke Thank you, KS. And to think all this time I've been citing the wrong authority! (Just look at how many replies were necessary before you answered David's question!)