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Do I need a Meg bushing

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TTwizted

Member
Location
florida
I have a 1 1/2 emt with #4s going from the panel to a disco. I have a 8x8 metal box connected to the panel with a chase nipple that is megged and the 1 1/2 going from 8x8 box to disco not megged but I have a plastic bushing since I megged the one with the chase nipple. On the other side I have the rigid nipple megged and one going to disco megged incase u were wondering. Do I have a violation?


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TTwizted

Member
Location
florida
hillbilly1 said:
Maybe a European thing? Never heard it called that either!
Click to expand...

U never heard of a Meg bushing?
ddb420d44816eea48ed6d2eb5f8ceac6.jpg

Maybe it’s a commercial thing.


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T

TTwizted

Member
Location
florida
infinity said:
Does the disco have concentric or eccentric KO's? I never heard a bonding bushing called megged. MIGB maybe.
Click to expand...

I megged the disco I’m not worried about that. It’s concentric fyi. But my question is by the panel I have a box with a chase nipple connecting the panel to the box which has a meg bushing but the pipe that goes from the top of that box by the panel doesn’t have a meg bushing on it but it has a plastic bushing.


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infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
You said 480 volts so here the relevant code section:

250.97 Bonding for Over 250 Volts.
For circuits of over 250 volts to ground, the electrical continuity 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).
Exception: Where oversized, concentric, or eccentric knockouts are not encountered, or where a box or enclosure with concentric or eccentric knockouts is listed to provide a reliable bonding connection, the following methods shall be permitted:
(1) Threadless couplings and connectors for cables with metal sheaths
(2) Two locknuts, on rigid metal conduit or intermediate metal conduit, one inside and one outside of boxes and cabinets
(3) Fittings with shoulders that seat firmly against the box or cabinet, such as electrical metallic tubing connectors, flexible metal conduit connectors, and cable connectors, with one locknut on the inside of boxes and cabinets
(4)Listed fittings
Click to expand...
 
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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
TTwizted said:
U never heard of a Meg bushing?
ddb420d44816eea48ed6d2eb5f8ceac6.jpg

Maybe it’s a commercial thing.


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Click to expand...
I’ve done commercial all my life, and only known them as bond bushings. Never heard of it called a Meg, and I’ve worked in quite a few states north, south, east and west. Don’t know if many residential guys that have ever used one. They use pvc for everything.
 
Little Bill

Little Bill

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Location
Tennessee NEC:2017
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Semi-Retired Electrician
TTwizted said:
I megged the disco I’m not worried about that. It’s concentric fyi. But my question is by the panel I have a box with a chase nipple connecting the panel to the box which has a meg bushing but the pipe that goes from the top of that box by the panel doesn’t have a meg bushing on it but it has a plastic bushing.


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Click to expand...
When I read that it sounds like you used a megometer to check the wiring. That's what some say when using a Meg.
Don't know how that term applies to a bonding bushing.
 
T

TTwizted

Member
Location
florida
Little Bill said:
When I read that it sounds like you used a megometer to check the wiring. That's what some say when using a Meg.
Don't know how that term applies to a bonding bushing.
Click to expand...

I see the confusion. I didn’t use a megometer. Besides a eccentric or concentric and coming up from the ground with feeders when do I need a bonding bushing


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Carultch

Senior Member
Location
Massachusetts
TTwizted said:
I see the confusion. I didn’t use a megometer. Besides a eccentric or concentric and coming up from the ground with feeders when do I need a bonding bushing


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Click to expand...

In general, you need a bonding bushing, any time there is missing or impaired continuity of the raceway, that would hinder it from being electrically continuous with the equipment grounding conductor system.

An example of missing continuity, is connecting to a plastic enclosure.
An example of impaired continuity, is whenever you have ring knockouts remaining. If you use up all the knockouts, they might as well not be there in the first place. But if they remain, the joints between ring knockouts are only "strong" enough to carry faults driven by a source that is 250V to ground or less. That is, unless the equipment is otherwise listed for higher voltages.

Conduits containing service conductors or GEC's are a special case where they can be required, even if there isn't missing or impaired continuity.
 
T

TTwizted

Member
Location
florida
Carultch said:
In general, you need a bonding bushing, any time there is missing or impaired continuity of the raceway, that would hinder it from being electrically continuous with the equipment grounding conductor system.

An example of missing continuity, is connecting to a plastic enclosure.
An example of impaired continuity, is whenever you have ring knockouts remaining. If you use up all the knockouts, they might as well not be there in the first place. But if they remain, the joints between ring knockouts are only "strong" enough to carry faults driven by a source that is 250V to ground or less. That is, unless the equipment is otherwise listed for higher voltages.

Conduits containing service conductors or GEC's are a special case where they can be required, even if there isn't missing or impaired continuity.
Click to expand...

Thank you


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