250.64(E)

[gooseloony]

Can't seem to find a clear answer to these questions RE:250.64(E)---

1) The Article states bonding of both ends of GEC installed in metal conduit or in my case as armored sheathing, at the rod end its achieved with an "armored" ground clamp but at the panel end what is the conector approved for this (around here I see everyone using a "romex" clamp which I believe is NOT listing for bonding/grounding)
I am trying to attach a photo but no sure it will work

2) When the GEC is installed in metallic---is the metal conduit/armor only required to be bonded at the can or the GEC to the metal conduit/armor (via bond bushing)?

NOTE: have looked at the NEC Illustrated and Mike Holt Illustrated and its unclear if its the bonding of the GEC or the metal/armor or both

 

[Smart $]

"Ferrous metal raceways and enclosures shall be bonded at each end of the raceway or enclosure to the grounding electrode or grounding electrode conductor."

"Bonding shall be in compliance with 250.92(B) and ensured by one of the methods in 250.92(B)(2) through (B)(4)."

"...
(2) Connections utilizing threaded couplings or threaded hubs on enclosures if made up wrenchtight
(3) Threadless couplings and connectors if made up tight for metal raceways and metal-clad cables
(4) Other listed devices, such as bonding-type locknuts, bushings, or bushings with bonding jumpers"

 

[Smart $]

JMO...

If the connector is listed for grounding (almost all metal connectors are), the bonding bushing is not required.

Mind you, the connector must also be listed for use with the raceway...

 

[gooseloony]

So it's the bonding of the raceway to the enclosure NOT the GEC to the raceway (at the enclosure)? And would you agree the NM Cable (romex) connector is not listed for use with armor cable (as a bond or otherwise)? If so does anyone know of a connector listed for use on armor ground cable?

 

[infinity]

Are you sure that the connector is only for NM? I've used two screw MC connectors before.

 

[Smart $]

So it's the bonding of the raceway to the enclosure NOT the GEC to the raceway (at the enclosure)? And would you agree the NM Cable (romex) connector is not listed for use with armor cable (as a bond or otherwise)? If so does anyone know of a connector listed for use on armor ground cable?

The main requirement is for the GEC-enclosing equipment to be electrically continuous from point to point along the path of the GEC. The GEC will be bonded to the enclosure and in turn to the enclosure end of the armor through the listed connector.

Just use an armored cable connector. Several examples (not all of them, just the ones with armored cable in the part title)...

http://www.emersonindustrial.com/en...d_Cable_Flexible_Metal_Conduit_Connectors.pdf

 

[gooseloony]

Thanks guys but...

Infinity--good point but would either or both be identified on the connectors themselves? How would one know if it was an MC two screw connector or a two screw NM Cable connector (not just on a box, that's where some of my confusion comes in)?

Smart--thanks for the link

 

[Smart $]

Are you sure that the connector is only for NM? I've used two screw MC connectors before.

I don't think it matters. The connector has to be listed as an armored cable connector.

 

[infinity]

Aren't most MC connectors also rated for AC cable?

It also brings up the question is this actually AC cable or cable armor? The NEC uses the latter as a type of protection for the GEC but what is it?

 

[Dennis Alwon]

I've never seen an armored cable clamp look like that but I don't use mc much. I have seen an nm cable clamp used as a bug

 

[gooseloony]

Still reading. Great responses, still not clear if MC, AC or NM Cable connectors are actually marked as such on each connector? Also, Infinity that's a good point.

 

[Smart $]

Aren't most MC connectors also rated for AC cable?

It also brings up the question is this actually AC cable or cable armor? The NEC uses the latter as a type of protection for the GEC but what is it?

I believe many MC connectors are also listde for AC... but I've never looked into it, and that's probably as far as I'll go. :huh:

Not sure if armored GEC is Type AC or not??? I've not seen any indication that it is Type AC.

 

[gooseloony]

After a little for research--see this link which does show a 2 screw connector (doesn't say its listed for bonding, maybe UL has that somewhere--can someone help with that?) but it does appear what I've seen being used are just "regular" NM cable connectors. Still really curious as to how each fitting would be identified as meeting the "listed for bonding" requirement.

http://www.cooperindustries.com/con...log-pdfs/setscrew-duplex-type-zincdiecast.pdf

 

[Smart $]

...maybe UL has that somewhere--can someone help with that?)...

Here's the link to the UL file:

http://database.ul.com/cgi-bin/XYV/...n=versionless&parent_id=1073984316&sequence=1

Follow the link near top: See General Information for Armored Cable Connectors, Type AC

...and that page says...

The basic standard used to investigate products in this category is ANSI/UL 514B, "Conduit, Tubing, and Cable Fittings."

UL514B standard essentially confirms all metal connectors as suitable for grounding.

 

[gooseloony]

Smart, thanks for the research, so appears AC connectors can be used on AC, MC and NMC and are not necessarily marked as such BUT what does UL say about NMC connectors used on AC and/or MC cable? That's what it appears I see being used all over on the Armor Ground Cable for GEC. If I can clear that up, I can save myself some grief.

 

[infinity]

You have to use a connector suitable for and listed for the thing that it's connecting. Most connectors do not tell you this on the connector itself. You would need to find the model number and investigate yourself as to whether or not it was being used properly with a particular wiring method. A connector solely listed for NM cable cannot be used for other wiring methods.

 

[Smart $]

Smart, thanks for the research, so appears AC connectors can be used on AC, MC and NMC and are not necessarily marked as such BUT what does UL say about NMC connectors used on AC and/or MC cable? That's what it appears I see being used all over on the Armor Ground Cable for GEC. If I can clear that up, I can save myself some grief.

Rob pretty much covered it, but I felt compelled to add...

"If it looks like a duck, quacks like a duck and walks like a duck..."does not apply here.

 

[MasterTheNEC]

Aren't most MC connectors also rated for AC cable?

It also brings up the question is this actually AC cable or cable armor? The NEC uses the latter as a type of protection for the GEC but what is it?

No, not always. If the clamp is listed for AC and MC it will be stated in the listing and on the product specs. Where do I get this info from, the manufacturer of such connectors.

 

[MasterTheNEC]

For additional clarity - While UL does state that AC Connectors can be used with MC Cable as I stated and as it is defined in the UL Whitebook (AWSX) " Additional Fittings- Connectors covered under Metal-Clad Cable Connectors, Type MC (skipping unneeded text) are also suitable for use with armored cable when specifically indicated on the device or carton." So as long as they are marked as such...have at it.

 

[Smart $]

...

"If it looks like a duck, quacks like a duck and walks like a duck..."does not apply here.

For additional clarity - While UL does state that AC Connectors can be used with MC Cable as I stated and as it is defined in the UL Whitebook (AWSX) " Additional Fittings- Connectors covered under Metal-Clad Cable Connectors, Type MC (skipping unneeded text) are also suitable for use with armored cable when specifically indicated on the device or carton." So as long as they are marked as such...have at it.

IIRC, I have never seen a 2-screw clamp connector marked on its body... always on packaging, cut sheet, etc. Then we have instances where such connectors are [seemingly*] listed for NM, SE, MC, and AC...

http://www.aifittings.com/catalog/files/pdf/sections/C-3-2.pdf

*I did not look up the file and part numbers to see if the non-asterisked connectors are listed for all types.

Finally, I would consider any such connector as a "non-violation", regardless of listing.