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#124418 09/30/06 11:34 AM
Joined: Mar 2005
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It gets more complicated when the GEC is going to water and the conduit only goes to the ceiling and then is wire only to the other end of the building.
At most fires I have seen the EMT couplings become pavement solder, leaving the pipe hanging from the wires. I think that may be why the connectors are listed for rigid only.
Alan--


Alan--
If it was easy, anyone could do it.
#124419 09/30/06 10:36 PM
Joined: Jul 2005
Posts: 73
S
Member
Pull an insulated wire and problem is solved.

#124420 10/01/06 02:37 AM
Joined: Oct 2005
Posts: 4
C
Junior Member
Doesn't that rebar need an approved clamp instead of an acorn?

#124421 10/01/06 04:00 AM
Joined: May 2003
Posts: 2,876
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e57 Offline
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In the very least an attempt was made... Although I don't see the point. They followed the letter of the code IMO, but not the way I would do it. 1/2" hub direct to the steel, RMC and a 1/2" hub/clamp to the re-bar. (Thats if it is even part of the electrode system?) Even then I would have done it nearer to, and direct to the service.

Surfinsparky, an insulated conductor as a GEC would still need to have the conduit bonded at both ends.
cptkinguru, an acorn is a listed clamp. (Although maybe not for that size wire)


Mark Heller
"Well - I oughta....." -Jackie Gleason
#124422 10/01/06 06:17 AM
Joined: Jul 2005
Posts: 73
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Then it would be okay for bonding?Let me go look this up.

#124423 10/01/06 09:56 AM
Joined: May 2002
Posts: 1,716
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I agree with Mark, they tried and in reality it works.

They could have used a bond bushing or a pipe clamp around the end of the EMT, anything that would join the conduit and conductor together so they would in essence become a single conductor.

Surfinsparky, the GEC can be bare or insulated.

Quote
250.62 Grounding Electrode Conductor Material

The grounding electrode conductor shall be of copper, aluminum, or copper-clad aluminum. The material selected shall be resistant to any corrosive condition existing at the installation or shall be suitably protected against corrosion. The conductor shall be solid or stranded, insulated, covered, or bare.

The reason for bonding both ends of the metallic conduit sleeve is so it will be in parallel with the GEC and negate the increased impedance caused by the separation of the two conductive paths, which in turn will reduce a "choke effect".

Bonding them together will actually lower the impedance to a lower value than the conductor alone.

Roger

#124424 10/01/06 12:20 PM
Joined: Mar 2005
Posts: 399
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Member
Surfinsparky, The GEC can be insulated but, Must still be bonded when it leaves a metal raceway.
95 % of fault current will be carried by the conduit not the wire. (Soares)
Arcing at the end of the conduit could cut the GEC. leaving no fault path.
Alan--
There is another photo of this in the Violations Photos "Store Wiring" showing an insulated GEC clamped with an NM connector.


[This message has been edited by Alan Nadon (edited 10-01-2006).]


Alan--
If it was easy, anyone could do it.
#124425 10/01/06 12:42 PM
Joined: Jan 2003
Posts: 4,391
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Moderator
Alan I really don't see the problem, if this is the worts you find on the job than you should be pleased.

All Ul listed raceway fittings are listed for grounding.

Now I understand a NM connector while listed for grounding is not actually listed to clamp a 4 AWG but what do you see happening or not happening.

I can run service conductors in EMT using die cast connectors and that would be acceptable bonding of the EMT even with unprotected conductors inside.

JMO, and I do agree your well within your rights to require this changed.

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts
#124426 10/01/06 06:27 PM
Joined: Dec 2000
Posts: 4,289
Member
http://www.tnb.com/contractor/docs/blackburn_grounding.pdf#search=%22blackburn%20CH34%22

Go to page F114 and look at the conduit hubs.
How about a #3930 for this application.?

#124427 10/01/06 09:15 PM
Joined: Jun 2003
Posts: 681
P
Member
I do not believe that NM connectors are listed for grounding purposes.

Rebar is not listed as an electrode as per 250.52(5)...it is listed as part of an electrode in .52(3).
Will this work? yes. Will that rebar last long in the soil environment? I do not know. So how long will the steel beam be "effectively grounded"?

The 2008 NEC will most likely have "effectively grounded" removed from the entire code book, as "effectively" is too subjective a term by itself.

[This message has been edited by PCBelarge (edited 10-01-2006).]


Pierre Belarge
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