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#39104 06/10/04 09:47 AM
Joined: Aug 2001
Posts: 545
A
aldav53 Offline OP
Member
Radar, how can some cities in LA use flex for a ground when it goes against the NEC code?


The Golden Rule - "The man with the gold makes the rule"
#39105 06/10/04 10:45 AM
Joined: Jun 2003
Posts: 1,143
D
Member
Seen the AL stuff, but never used it. All my AHJ's / employers have required/used steel.

[history lesson] As mentioned elsewhere on the board, "Rigid Metal Conduit/RMC" AKA "rigid" or "heavy wall" has it's origins in the late 1800's use of plumbing pipe to feed gas lamps in metropolitan areas. When Edison's newfangled "electical lights" came into being, most people wanted the new lights where the old ones were mounted - it was very easy to run the wires through the pipes, and so, with some modifications (including reaming of ends - learned, I'm sure, by fires caused by faulted insulation), we arrived at the "birth" of conduit.

IMC (Intermediate Metallic Tubing) and EMT (Electrical Metallic Tubing) were later descendents of this technology, once engineers realized that the pipe didn't have to hold pressure, just provide physical protection. Of course, IMC and RMC are still used where support of conductors or extreme physical or environmental hazards exist (Service masts, factory areas subject to damage, hazardous atmospheres), but 9 out of 10 people would identify EMT as "conduit" nowdays. [/history lesson]

A little off topic, but may I reccommend a Roto-split cutter if you do a lot of Greenfield work?

(Having used both, IMHO the Seatek cutter is superior to the Greenlee... faster, lighter, and easier to use, but here are links to both [Linked Image]
http://www.seatekco.com/rs-101a.htm
http://198.247.193.8/wwwroot/greenlee/details.cfm?id=4375&upc=34953

[This message has been edited by DougW (edited 06-10-2004).]

#39106 06/11/04 12:39 AM
Joined: Feb 2004
Posts: 1,438
Member
Scott,
From the LA city code on their website:

Quote

SEC. 93.0905. GROUNDING.

(Former Sec. 93.0905 Repealed by Ord. No. 164,136, Eff. 12/4/88.) (Former Sec. 93.0907. Redesignated by Ord. No. 162,834, Eff. 10/26/87.) (Including N.E.C. Section 350-5 as amended herein.)

Grounding. Flexible metal conduit shall be permitted as a grounding means where both the conduit and the fittings are approved for grounding. Where an equipment bonding jumper is required around flexible metal conduit, it shall be installed in accordance with Section 250-79.

EXCEPTION NO. 1. Flexible metal conduit shall be permitted as a grounding means if the total length in any ground return path is 6 feet (1.83m) or less, the conduit is terminated in fittings approved for grounding, and the circuit conductors contained therein are protected by overcurrent devices rated 20 amperes or less.

EXCEPTION NO. 2. Where flexible metal conduit and liquidtight flexible metal conduit are used in combination with each other, the total length of the combined ground return path shall not exceed 6 feet (1.83m).

LA City Electrical Codes

*Warning! above link is a LARGE document.. May cause your computer to have gastric distress! [Linked Image]

-Randy

PS... Are most FMC fitting "approved for grounding?"

#39107 06/11/04 04:52 PM
Joined: Apr 2004
Posts: 349
Member
It is certainly possible that the City of Los Angeles has changed back and now al-flex used as a ground path to 6' or less. I'll check it out and post what I find. Most commercial jobs used steel flex anyway, but not all.

On the NEC issue - there is no law stating a municipality or building department must use the NEC as a standard. Many years ago Los Angeles used to publish their own electrical code from scratch. In the 70's or so (I think), they decided to go with the NEC, but then also published a supplement which spelled out their deviations from the NEC. I think they still do this.

After some testing, they determined AL-Flex was suitable as a ground path in lengths up to 100' for 1/2" size. And yes, it had to be squarely cut.

Some other cities and local building departments adopted the standard set by Los Angeles, and some did not. So, if you wanted to use AL-Flex, you had to check with the local building authority to determine if it were allowed as a grounding path or not.

I know of some cases where electricians have had to go back and install grounding wires in otherwise completed work because they did not check, but assumed.

Radar


There are 10 types of people. Those who know binary, and those who don't.
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