Metal Wireway Concentrics

[George Stolz]

Do I need to bond around concentrics for an EMT containing a 480Y/277 circuit entering a metal wireway?

 

[tkb]

Do I need to bond around concentrics for an EMT containing a 480Y/277 circuit entering a metal wireway?

Yes, see 250.97

 

[kwired]

Yes, see 250.97

Also read the exception that follows.

If the wireway is listed for the KO to be used for bonding in this application then you do not have to have additional bonding methods.

 

[George Stolz]

Here's what I am looking at:

CONCENTRIC OR ECCENTRIC KNOCKOUTS​

All boxes with concentric or eccentric knockouts have been investigated for bonding and are suitable for bonding without any additional bonding means around concentric (or eccentric) knockouts where used in circuits above or below 250 V, and may be marked as such.

This is explicit, but doesn't apply to wireways IMO.

Metallic wireway installed in accordance with the product markings and manufacturer?s instructions is suitable for use as equipment grounding conductors, and is Listed for grounding.

What does "and is listed for grounding" mean?

 

[kwired]

Here's what I am looking at:


This is explicit, but doesn't apply to wireways IMO.


What does "and is listed for grounding" mean?

I don't know if the first part applies to wireways or not.

I don't think the second part is talking about concentric or eccentric knockouts but rather the wireway in general is acceptable for use as an equipment grounding conductor.

 

[George Stolz]

I don't know if the first part applies to wireways or not.

I would say with 95% certainty it does not.

I don't think the second part is talking about concentric or eccentric knockouts but rather the wireway in general is acceptable for use as an equipment grounding conductor.

Okay - but it says "and is listed for grounding" - what does that mean?

 

[tkb]

Also read the exception that follows.

If the wireway is listed for the KO to be used for bonding in this application then you do not have to have additional bonding methods.

He didn't say if his his KO's were listed for grounding as per the exception, so my answer to the the OP question would still be the same.

Am I suppose to assume?

 

[cadpoint]

Voting with Tim, for circuits above 250V to ground. Or as it reads as stated Article 250.97.

 

[kwired]

He didn't say if his his KO's were listed for grounding as per the exception, so my answer to the the OP question would still be the same.

Am I suppose to assume?

I did not say you are supposed to assume. I just said there is more information that may change things. If you were the inspector you can't reject it if the installer can prove it is listed for the purpose, but you as inspector would not need to know beforehand if it is listed or not.

 

[texie]

I think George raises a valid question. I think the electrical manufacturing industry does a very poor job of conveying information to the installer of the main points to be aware of in the listing of their products. Another one that comes to mind are raised square covers for receptacles, why don't they just come out and tell you if they are approved for grounding and you don't need a separate EGC jumper. It' like pulling teeth to get an answer.

 

[kwired]

Okay - but it says "and is listed for grounding" - what does that mean?

Good question - seems to be a little redundant wording tacked on - or something that needs clarification if it has some meaning other than what was mentioned before it.

I figured the whole thing means the wireway is just as much of a grouning conductor as a metal raceway is, but concentric/eccentric KO's are likely a different issue.

 

[infinity]

I figured the whole thing means the wireway is just as much of a grounding conductor as a metal raceway is, but concentric/eccentric KO's are likely a different issue.

My thoughts as well.

 

[John120/240]

Another one that comes to mind are raised square covers for receptacles, why don't they just come out and tell you if they are approved for grounding and you don't need a separate EGC jumper. It' like pulling teeth to get an answer.

Attach your ground wire to the 4" square box, then to the recptacle. Are you saying that

the AHJ required a seperate ground wire ?

 

[texie]

Attach your ground wire to the 4" square box, then to the recptacle. Are you saying that

the AHJ required a seperate ground wire ?

No, I'm saying that you don't need an EGC jumper to the recep. if the cover is "approved" as a grounding means. See 250.146(A). How do I know it is approved? Kinda like George's question of wireway concentric KO's, how do you know at a moments notice in the field?

 

[kwired]

No, I'm saying that you don't need an EGC jumper to the recep. if the cover is "approved" as a grounding means. See 250.146(A). How do I know it is approved? Kinda like George's question of wireway concentric KO's, how do you know at a moments notice in the field?

If the raised cover has a flat area that contacts the box (similar to mud rings) it is most likely approved as a grounding means.

If the raised cover is only the thickness of the cover itself where it contacts the box (these usually also have their own mounting screws supplied as the screws already in the box are not long enough) it is probably not approved as a grounding means.

 

[Dennis Alwon]

The first question I asked myself is a wireway listed as an egc. I see nothing in metal raceways that says it is although I suspect some may be listed that way. If it isn't listed as an means of grounding as emt is then wouldn't we have to bond no matter what the voltage. I suspect that a wireway is just a large jb but where do we find if it is listed as a ground.

 

[kwired]

The first question I asked myself is a wireway listed as an egc. I see nothing in metal raceways that says it is although I suspect some may be listed that way. If it isn't listed as an means of grounding as emt is then wouldn't we have to bond no matter what the voltage. I suspect that a wireway is just a large jb but where do we find if it is listed as a ground.

How about the quotes from the white book that George posted in post #4?

add: as long as the wireway is listed it should meet those requirements.

 

[Dennis Alwon]

How about the quotes from the white book that George posted in post #4?

add: as long as the wireway is listed it should meet those requirements.

Thanks I skimmed thru--I am curious as to why it is not written in art 376.