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Electrical Metallic Tubing Installed Underground #104674
10/07/03 08:17 AM
10/07/03 08:17 AM
Joe Tedesco  Offline OP
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
[Linked Image]

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).]


Joe Tedesco, NEC Consultant
2017 / 2014 NEC & Related Books and Study Guides
Re: Electrical Metallic Tubing Installed Underground #104675
10/07/03 09:43 AM
10/07/03 09:43 AM
P
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
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?

Re: Electrical Metallic Tubing Installed Underground #104676
10/07/03 03:38 PM
10/07/03 03:38 PM
I
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Paul, EMT is roughly the same as the exhaust pipe on a car.

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: Electrical Metallic Tubing Installed Underground #104677
10/08/03 02:23 PM
10/08/03 02:23 PM
K
kale  Offline
Member
Joined: Nov 2002
Posts: 174
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.

Re: Electrical Metallic Tubing Installed Underground #104678
10/08/03 05:14 PM
10/08/03 05:14 PM
P
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
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.

Re: Electrical Metallic Tubing Installed Underground #104679
10/08/03 07:37 PM
10/08/03 07:37 PM
T
ThinkGood  Offline
Member
Joined: Aug 2002
Posts: 1,081
Milwaukee, WI
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.

Re: Electrical Metallic Tubing Installed Underground #104680
10/09/03 12:09 AM
10/09/03 12:09 AM
B
Big Jim  Offline
Member
Joined: Jul 2003
Posts: 394
Denver, CO USA
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.

Re: Electrical Metallic Tubing Installed Underground #104681
10/09/03 04:54 AM
10/09/03 04:54 AM
Joe Tedesco  Offline OP
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
This picture was taken in Las Vegas last year.

[Linked Image]


Joe Tedesco, NEC Consultant
Re: Electrical Metallic Tubing Installed Underground #104682
10/09/03 08:12 PM
10/09/03 08:12 PM
G
Gwz  Offline
Member
Joined: Apr 2002
Posts: 197
You're just " nitpicking ".

Re: Electrical Metallic Tubing Installed Underground #104683
01/01/04 10:12 AM
01/01/04 10:12 AM
Joe Tedesco  Offline OP
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
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?


Joe Tedesco, NEC Consultant
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