bonding bushing / concentric KO

[infinity]

Ok, but in my pic, the smallest KO, a 3/4 will have the locknuts rest on the other part of the KO ring, not the chassis. If I were to break out the 3/4 and 1" and install a 1" pipe, then it would be against the chassis.

~Matt

Does it matter? For under 250 volts the KO is suitable for bonding whether it's on a ring or not.

 

[TOOL_5150]

Does it matter? For under 250 volts the KO is suitable for bonding whether it's on a ring or not.

It does matter, Im trying to learn something here. I just want to make sure I know what I am talking about when I talk to the inspector tomarrow.

~Matt

 

[480sparky]

From CH's Application catalog:

 

[infinity]

It does matter, Im trying to learn something here. I just want to make sure I know what I am talking about when I talk to the inspector tomarrow.

~Matt

Sorry, I was just trying to say that either on the ring or on the panel under 250 volts it does not matter. Ask the inspector for a code article he would cite for requiring a bonding bushing.

 

[TOOL_5150]

From CH's Application catalog:

Allright So mechanically there isnt much different between eccentric and tangential - eccentric is just more rounded.

 

[curt swartz]

Matt, what city was this in?

 

[TOOL_5150]

Sorry, I was just trying to say that either on the ring or on the panel under 250 volts it does not matter. Ask the inspector for a code article he would cite for requiring a bonding bushing.

Got it - thank you!


~Matt

 

[TOOL_5150]

Matt, what city was this in?

petaluma

~Matt

 

[480sparky]

Allright So mechanically there isnt much different between eccentric and tangential - eccentric is just more rounded.

From my roaming around the information superhighway, it appears that what most manufacturers call eccentric KOs are limited to two KOs, while tangenial KOs have three or more KO options.

 

[TOOL_5150]

From my roaming around the information superhighway, it appears that what most manufacturers call eccentric KOs are limited to two KOs, while tangenial KOs have three or more KO options.

Very good point - Now that I think about it I have seen the same thing.


~Matt

 

[Pierre C Belarge]

I did not read the whole thread, so I may be repeating what someone else has posted...If so, I am sorry.

From the UL White Book (2008):

GROUNDING AND BONDING
EQUIPMENT (KDER)
USE
This category covers bonding devices, ground clamps, grounding and
bonding bushings and locknuts, ground rods, armored grounding wire, protector
grounding wire, grounding wedges, ground clips for securing the
ground wire to an outlet box, water meter shunts, and similar equipment.
Some devices are to be assembled to wire using a special tool specified by
the manufacturer. Such special tooling is identified by appropriate marking
on or within the device shipping carton.
Grounding and Bonding Bushings
— Bonding bushings for use with conduit fittings, tubing (EMT) fittings, threaded rigid metal and intermediate metal conduit, or unthreaded rigid metal and intermediate metal conduit

are provided with means (usually one or more set screws) for reliably bonding the bushing (and the conduit on which it is attached) to the metal equipment enclosure or box. They provide the electrical continuity required by the NEC at service equipment and for circuits rated over 250 V.

Means for connecting a grounding or bonding conductor are not provided and if there is need for such a conductor a grounding bushing should be used. Grounding bushings for use with conduit fittings, tubing (EMT) fittings, threaded rigid metal and intermediate metal conduit, or unthreaded rigid metal and intermediate metal conduit have provision for the connection of a bonding or grounding wire or have means for mounting a wire connector available from the manufacturer. Such a bushing may also have means (usually one or more set screws) for reliably bonding the bushing to the metal equipment enclosure or box in the same manner that this is accomplished by a bonding bushing. Grounding bushings provide the electrical continuity required by the NEC at service equipment and for circuits rated over 250 V.
They may be used with or without a bonding or grounding conductor as determined by the bonding or grounding function that is intended to be​

accomplished.​

​

 

[Pierre C Belarge]

2008 White Book


EMT-

Grounding ​

​

​

​

​

? These fittings are considered suitable for grounding for use
in circuits over and under 250 V and where installed in accordance with
ANSI/NFPA 70, ??National Electrical Code.??​

Metal Boxes (QCIT)

Metallic Outlet Boxes (QCIT)−​

​

​

​

Continued
​

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.

 

[Pierre C Belarge]

From your pictures and explanation, your installation meets the current codes, and UL Standards.

'Tangential and Eccentric' are interchangable language, such as 'Hazardous and Classified' locations are.


Generally speaking, most manufacturers have their panels/enclosures tested so that the KOs and Eccentrics are listed as suitable for bonding purposes.
Eccentrics have been designed specifically to allow for more current to flow during fault conditions.
Remember that in Matt's picture, the enclosure is painted. As an inspector, I look to make sure the locknuts have removed the paint as they are being installed.

 

[TOOL_5150]

Pierre, Do you have anything pertaining to RMC directly about this matter?


~Matt

 

[suemarkp]

Another solution - how is the conduit bonded at the other end? Are there concentrics/eccentrics there too, or a pipe sized hole? I think you only have to bond one end of the raceway if you make up all the fittings wrench tight.

 

[TOOL_5150]

its goes to a 3R 6x6x4 box into a 3/4 hole. That box had a ground lug installed as well.


~Matt

 

[mweaver]

Manufacturer's panels / enclosures listed for bonding purposes...

Manufacturer's panels / enclosures listed for bonding purposes...

Pierre,

In your post #53, you stated:

Generally speaking, most manufacturers have their panels/enclosures tested so that the KOs and Eccentrics are listed as suitable for bonding purposes.
Eccentrics have been designed specifically to allow for more current to flow during fault conditions.

Can you point me to any manufacturer's literature which notes manufacturer's panels and enclosures incorporating KOs which have been listed for bonding purposes??

My understanding is that listed 4 square and 4-11/16 boxes are listed for grounding above and below 250-volts with or without eccentric - concentric KOs ... (can be confirmed in UL White Book)

I was not aware of any other manufacturer's panels / enclosures which have KOs listed for bonding purposes. This would definately be valuable info to have on hand.

I do appreciate your help,

mweaver

 

[don_resqcapt19]

...
Generally speaking, most manufacturers have their panels/enclosures tested so that the KOs and Eccentrics are listed as suitable for bonding purposes.
...

Pierre,
It is my understanding that most enclosures for panels and disconnects are not so listed.

 

[Pierre C Belarge]

Other than contacting the manufacturer or taking a look at the standards they adhere to when manufacturering the enclosures/boxes, I cannot provide you with that direct info. I do not have a copy of the standard.
You may want to contact the manufacturer via email, so you have a response in writing.
I myself have spoken to a couple of different manufacturer's reps about this very topic.
About 5-7 years ago, the standards and methods they have chosen to manufacture KOs changed. That is one of the reasons the KOs are more difficult to remove, they are better able to withstand the fault current.

I will add two additional comments.
Paint on the enclosure had to be removed either by hand or the fitting (mostly locknuts) has to be capable of removing the paint when installed.
When installing to older panels, one needs to be careful, as they may not have KOs that are suitable as part of the grounding path.

 

[George Stolz]

Pierre, that was kinda my point the last time we discussed this - you are under the impression, and forward the notion, that all metal enclosures, cabinets, and so on are the same as four-square boxes, but they fall under different listings.

I am willing to entertain the notion, but until you provide proof, you probably shouldn't make it sound as though all cabinets fall under the same rule, IMO.