That's one of the reasons why I go with rigid if protection is required by the AHJ for a GEC or bonding jumper... hate the jury-rigged stuff and rigid isn't all that terrible to bend.



Though the jury-rigged methods are common and do pass, what about neat and workman like?

Maybe it's time someone invents something better for EMT... assuming it doesn't already exist. All I've seen is what you see.

Joe

JJM, that is the connector I use on EMT- together with an EMT connector, of course!

Actually I would consider the two photo examples to be "neat and workman" like. The Romex clamp is a nice solution. Now if the ground wire just exited the raw conduit I would consider that a bit sloppy but it would still probably pass.

Look closely at the left of the second pic..it seems that the screw for the strap is not driven all the way in. Violation?

Even though there is obviously substantial metal to metal contact with the bare copper ground inside the EMT, The EMT must still be bonded by a listed means... Are those 2 screw connectors listed for this purpose?

I've used the clamp in JJM's post with an EMT connector before with no complaints from AHJ's

Gus, the conductor must be bonded to both ends of the ferrous raceway per 250.64(E)


Excerpt

Roger

I think I would reject the use of loomex connectors at the ends of the raceway as bonding method, but a bonding bushing a short piece of #6 and a split bolt rated for #6 and 3/0 or a lug under the same bolt as the ground lug would make me happy.

Is conduit considered a 'ferrous metal enclosure' ?

RSlater,
RSmike

RSmike, the second sentence covers the raceway.

250.92(A)(3) requires the same.


This is also explained on pages 126 and 127 of the 9th edition of Soares.

Roger

[This message has been edited by Roger (edited 09-29-2006).]

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--

Pull an insulated wire and problem is solved.

Doesn't that rebar need an approved clamp instead of an acorn?

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)

Then it would be okay for bonding?Let me go look this up.

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.


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

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 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

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.?

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).]

I stand corrected (and learned something in the process), the Erico acorn clamp is listed for use on groundrods AND rebar with a wire size of #2 or 1/0 depending on the part number.
Jake

Yes Scott a 3930 or two would be just the bees knees.

From what I could tell the 3930 is for conduit, i.e. rigid.
The JP- connectors, above the 3930 in the catalogue, are listed for use with EMT but, it has a maximum wire size of # 6.
Alan--

Surfinsparky - Pulling an insulated wire won't solve the problem were local code requires BX, MC or conduit; they want the GEC to have the same physical protection.

A friend of mine who doesn't do much work in NYC got red tagged on 200A residential service upgrade for using an insulated #4 for the GEC. BS, I know. Does it all the time outside NYC and never had a problem, always passed, but in NYC the GEC had to be in raceway (conduit) and of course, bonded at both ends.

Roger - You're absolutely correct on the "choke" effect of poor or non-existent bonding of a metal raceway for the GEC. Excellent point.

Joe

In NYC or any other big city the larger the copper, the more temping it is to be physicaly damged while being stolen. The conduit is there to help hide it...

Where I'm at in SF, it depends on what neighborhood you're in, and general mood of the inspector. But the safe side is to just pipe it if accessable to the public in anyway. Not behind locked door or gate.... People do snip and steal them...


[This message has been edited by e57 (edited 10-07-2006).]