Equipment Bonding

[joec]

Two issues I would appreciate clarification on...

First issue--If I understand correctly 1/2" or larger LFMC or conduit is an acceptable EGC. I'm curious as to why, if an EGC is run, it must be terminated at a single point in any panel it runs through that has conductor terminations. It seems as though using conduit as an EGC is less effective than single point bonding. I prefer to see an EGC run and terminated at the same point but I'm looking at 10+ years and older equipment and can't just write up bonding connections if they are code compliant.

Second issue--Class 2 Division II bonding. I have only found information regarding bonding at the service disconnect for C2DII areas. I have a lot of conduit being used as EGC throughout the system with no bonding locknuts or bushings. I would like to know the requirements.

Thanks for any help with this!

 

[iwire]

Re: Equipment Bonding

Originally posted by joec:
First issue--If I understand correctly 1/2" or larger LFMC or conduit is an acceptable EGC.

It can be, look at 250.118(7) to get the specifics.

Originally posted by joec:
I'm curious as to why, if an EGC is run, it must be terminated at a single point in any panel it runs through that has conductor terminations.

What do you mean by single point? That term does not sound like one from the NEC.

You are correct that if a grounding conductor is run it must be connected to each enclosure it passes threw if the conductors with it splice or terminate in that enclosure.

See 250.148 for the specifics.

Originally posted by joec:
It seems as though using conduit as an EGC is less effective than single point bonding. I prefer to see an EGC run and terminated at the same point but I'm looking at 10+ years and older equipment and can't just write up bonding connections if they are code compliant.

Using conduit as the EGC is code compliant to this day, again look to 250.118

I am not familiar with classified location rules.

 

[don_resqcapt19]

Re: Equipment Bonding

Joe,

I have a lot of conduit being used as EGC throughout the system with no bonding locknuts or bushings.

Look at 501.16(A).

(A) Bonding. The locknut-bushing and double-locknut types of contacts shall not be depended on for bonding purposes, but bonding jumpers with proper fittings or other approved means of bonding shall be used. Such means of bonding shall apply to all intervening raceways, fittings, boxes, enclosures, and so forth between Class I locations and the point of grounding for service equipment or point of grounding of a separately derived system.

Don

 

[joec]

Re: Equipment Bonding

Bob,

By single point I meant any EGC connections in a panel must be under the same terminal or lug. I can't find a reference for it either though.

Don,

I have a lot of corrections to make in the C2DII area I was referring to. I just couldn't believe that bonding jumpers or EGCs weren't run on original installation if they were required.

Thank you both for your help!

 

[iwire]

Re: Equipment Bonding

Originally posted by joec:
Bob,

By single point I meant any EGC connections in a panel must be under the same terminal or lug. I can't find a reference for it either though.

Not an NEC requirement and could very well be an NEC violation if the terminal or lug is not listed for more than one conductor.

 

[hurk27]

Re: Equipment Bonding

EGC connections in a panel must be under the same terminal or lug. I can't find a reference for it either though.

And I don't think you will as The grounding bar or even the neutral bar in service equipment is considered as a single point bond connection point. The grounding electrode conductor is also required to connect to the grounded conductor at a single point at the main service disconnect. And 250.24(A)(4) tells us that the grounding bar is a allowed conductor for making this connection. And 250.102(A) "A bonding jumper shall be a wire, bus, screw, or similar suitable conductor".
And as Bob has said many terminals are not listed for more than one conductor under a lug.

As the hazardous location Issue 250.100 requires us to use the methods in 250.92(B) to meet it's requirements for bonding of raceways. So we have to look at these requirement for these locations.

AS for LFMC 350.60
Where used to connect equipment where flexibility is required, an equipment grounding conductor shall be installed.
But in the FPN:
FPN: See 501.16(B), 502.16(B), and 503.16(B) for types of equipment grounding conductors.

[ November 29, 2004, 03:01 AM: Message edited by: hurk27 ]

 

[john m. caloggero]

Re: Equipment Bonding

JoeC: There are some very important rules that you have to review. Section 250.118(7) covers LFMC. LFMC can be used as an EGC under very specific conditions. They are: (1)Connectors must be listed for grounding, (2) The circuits in 3/8" and 1/2" LFMC must not exceed 20 amps, (3)The total ground-fault path cannot exceed 6 ft. For 3/4" up to 1-1/4": (1)Connectors must be listed for grounding, (2)The circuit OCP must not exceed 60 amps, (3)The total ground-fault path cannot exceed 6 ft. Where any of the prerequisites are exceed, an EGC must be installed in the raceway with the circuit conductors.

 

[joec]

Re: Equipment Bonding

Thanks to all for your replies. Including code references to study will help support my case when trying to make changes on installations that "have been working fine for years". Too many people don't understand how critical bonding is until there is a fire or fatality when an OCPD doesn't clear a fault condition. I'm trying to improve our 'sense of urgency' on safe installation.

Thanks again!

 

[pierre]

Re: Equipment Bonding

There are many references out there on bonding, such as Google.com - type in any part of bonding you may be interested in and buckle up.
Soares Book on Grounding 8th Edition, Stallcup's Electrical Grounding and Bonding simplified, IEEE Green Book, and Mike Holt's book on Grounding and Bonding are a few to get started on. Oh and the NEC Art 250 and 250.3.
Good luck and post back in a few years to let us know how it is going

Pierre

 

[joec]

Re: Equipment Bonding

Thanks Pierre! It probably will take a few years to get everyone understanding this. That's not meant to discredit anyone in my company. It's a process of educating everyone involved on an issue that doesn't directly effect production and convincing supervisors, managers and all of our electricians that the work needs to be done and the money needs to be spent.