In Arizona doesn't seem to withstand the effects of the earth?

What does UL have to say about this and does the NEC cover this situation?



[This message has been edited by Joe Tedesco (edited 03-07-2005).]

That looks bad, especially for a dry climate like Arizona. Or is this the result of galvanic action of some kind?

By the way, what's the usual thickness of the metal used for EMT?

Paul, EMT is roughly the same as the exhaust pipe on a car.

Bob

EMT wall thickness runs from 0.042 for 1/2 inch to .083 for 4 inch.

Compare that to Rigid Steel which runs from .104 to .225.

BTW IMC runs from .070 to .140.

Thanks. There was some thinwall conduit used in the U.K. in the past, but nowadays we don't really have an equivalent to EMT in general work, just PVC or heavy-gauge steel.

ARTICLE 358
Electrical Metallic Tubing: Type EMT

358.10 Uses Permitted.
...
(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.

358.12 Uses Not Permitted. EMT shall not be used under the following conditions:
(1) Where, during installation or afterward, it will be subject to severe physical damage
(2) Where protected from corrosion solely by enamel
...
(6) Where practicable, dissimilar metals in contact anywhere in the system shall be avoided to eliminate the possibility of galvanic action
Exception: Aluminum fittings and enclosures shall be permitted to be used with steel EMT where not subject to severe corrosive influences.

It looks like it may be "lava rock" around those pieces. If so, I have found that lava rock is very corosive, even to galvanized material. I've seen it eat completely through window wells when it was used around the foundation. This may be a location where Suitable for conditions is important.

This picture was taken in Las Vegas last year.

You're just " nitpicking ".

Gwz
continued ....

Define "nitpicking"

How in the heck are you! What's up? Did you send in any Proposals, and did they get accepted?

How about Comments?

pvc schedual 40,( or 80 if subject to abuse), would have solved the problem in both pictures. or pvc coated rigid could have been used for the stub downs, with a more economical change over to pvc for the remainder of the underground run.

I have learned in many instances joe that concrete is very corrosive thus that emt installation there shows proof of that. One other thing you guys might watch is your summertime jobs when ready mix companies tend to add more flyash to their mixtures instead of cement 1 or 2. Flyash(made up of mostly potash which is highly corrosive)will definately help corrode pipes such as you see here. I've learned this through experience in wiring of 30 or central batch ready mix plants. Also rizer has hit the nail on the head with the reply he posted,however i just like to add one thing to that even when running pvc underground into the inside of building and then stubbing up with metal raceway i would highly recommend that your pvc conduit be LS rated.

[This message has been edited by wirenut73 (edited 05-27-2004).]