Bonding bushing required?

[electrofelon]

Consider the following: >250 v to ground circuit in regular Mc cable. Concentric not listed for grounding knockouts on both ends. I only need a bonding bushing on one end correct? If one end had the same concentrics and the other a punched hole, I would be all set correct?

 

[ActionDave]

I don't think you need a bond bushing in either case since the sheathe of plain MC is not an egc.

 

[iwire]

I don't have a code book handy but I think bonding is still required even for MC

 

[ActionDave]

I don't have a code book handy....

Here's the section you must have been thinking of that makes you correct..

250.97 Bonding for Over 250 Volts
For circuits of over 250 volts to ground, the electrical conti-
nuity of metal raceways and cables with metal sheaths that
contain any conductor other than service conductors shall be
ensured by one or more of the methods specified for services
in 250.92(B), except for (B)(1).

I don't get to use MC for feeders ever. They make a connector that can be used with a bond bushing.....???

 

[infinity]

I don't think you need a bond bushing in either case since the sheathe of plain MC is not an egc.

I agree with Dave and the same logic would apply to certain sizes of FMC.

 

[Smart $]

...
I don't get to use MC for feeders ever. They make a connector that can be used with a bond bushing.....???

Applies to branch circuits, too. For example 480/277 branch circuits such as for lighting.

They make threaded MC connectors with locknuts. What more do you need in a connector?

 

[iwire]

I agree with Dave and the same logic would apply to certain sizes of FMC.

Read 250.97

 

[electrofelon]

I don't think you need a bond bushing in either case since the sheathe of plain MC is not an egc.

That was my initial thought, but I don't see any wording giving an allowance for if the metal is not used as an egc. Does everyone agree I only need the rigorous bonding on one end?

 

[iwire]

That was my initial thought, but I don't see any wording giving an allowance for if the metal is not used as an egc. Does everyone agree I only need the rigorous bonding on one end?

You need bonding at each end if both ends have concentric KOs.

I don't disagree with your logic, I just do not see it in 250.97.

 

[electrofelon]

You need bonding at each end if both ends have concentric KOs.

I don't disagree with your logic, I just do not see it in 250.97.

I am not able to check the wording right now, but it seems that would be analagous to how we are only required to bond one end of a service raceway. Iirc that also does explicitly say that it is only necessary to bond on one end.

 

[iwire]

I am not able to check the wording right now, but it seems that would be analagous to how we are only required to bond one end of a service raceway. Iirc that also does explicitly say that it is only necessary to bond on one end.

ActionDave posted 250.97 above, there is no way to read that (IMO) in a way that allows not bonding around a concentric just because the raceway or cable sheath was bonded at the other end.