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#39094 06/09/04 11:27 AM
Joined: Aug 2001
Posts: 545
aldav53 Offline OP
Are there requirements where steel flexible conduit has to be used over Aluminum? Is steel considered ridgid?

The Golden Rule - "The man with the gold makes the rule"
#39095 06/09/04 04:59 PM
Joined: Dec 2003
Posts: 886
None that I can think of other than maybe environmental.

Both are FMC or Greenfield so no, steel is not rigid.


#39096 06/09/04 05:06 PM
Joined: Dec 2003
Posts: 751
Aluminum is lighter and cheaper than steel. Steel is stronger, more abuse resistant. What are the conditions of use at your installation? Unless the engineer specifies steel, 99% of the time, aluminum will be chosen because of the lighter weight (easier installation) and lower cost.

Steel flex is still flexible and not rigid. Rigid is schedule 80 PVC, schedule 40 PVC, heavy wall metal conduit or intermediate metal conduit. Even though Electrical Metallic Tubing (EMT) seems to be rigid, nowhere is it refered to as a rigid conduit.


#39097 06/09/04 05:24 PM
Joined: Apr 2004
Posts: 349
Pay attention to job specifications, if there are any. In many specs, especially public works, steel flex is specified, and therefore aluminum flex would not comply. Remember, engineers do not have to install the stuff.

One other issue, there are cities in and around the Los Angeles area where approved types of aluminum flex conduit can be utilized as the grounding path, even when the length exceeds 6'. I believe it's 100' for 1/2" Al-Flex, less for 3/4", and less again for 1".

There are problems with the interpretation of this ruling, and it does not apply in all cities. Without saying this is a good or bad idea, many local contractors take advantage of the savings by not providing ground wires when installing Al-Flex.


There are 10 types of people. Those who know binary, and those who don't.
#39098 06/09/04 05:35 PM
Joined: Apr 2003
Posts: 139
Another consideration is that AL is not magnetic and you will not have issues such as Hyteresis.

Bryan P. Holland, ECO.
Secretary - IAEI Florida Chapter
#39099 06/09/04 07:47 PM
Joined: Apr 2002
Posts: 914
But the Aluminum stuff will turn your hands black and everything you touch. For that reason I prefer the steel.

#39100 06/09/04 07:56 PM
Joined: May 2004
Posts: 73
You also can't use some of the set screw connectors, probably cuz they punch a hole in it

#39101 06/09/04 07:58 PM
Joined: Dec 2003
Posts: 524
... Also, with aluminum,you have to use an "MC" type connector,where the binding screw won't pierce the jacket,..with steel, you can use the standard "Bx" connector..

.."if it ain't fixed,don't break a Licensed Electrician"
#39102 06/09/04 08:00 PM
Joined: Dec 2003
Posts: 524
... Ralph, you beat me to the punch line!!,.. [Linked Image] [Linked Image] [Linked Image] [Linked Image] I type way too slow..

.."if it ain't fixed,don't break a Licensed Electrician"
#39103 06/10/04 09:19 AM
Joined: Dec 2000
Posts: 4,293
Is the Aluminum flex still OK as a grounding path in LA??
Somewhere I've got a "square cutter", a tool that was used to hold flex so it could be cut with a hacksaw. It seems like that was a requirement for using the flex as a ground.
I haven't used it in about 20 years.

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