When are you required to use grounding bushings?

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zappy

zappy

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CA.
Running rigid on a roof going into 24 x 24 can using locknut with gasket on both sides it's insulating the pipe from the can. I imagine this is one instance. What are others? Thank you for your help.
 
zappy said:
Running rigid on a roof going into 24 x 24 can using locknut with gasket on both sides it's insulating the pipe from the can. I imagine this is one instance. What are others? Thank you for your help.
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any time for grounding continuity or bonding such as service.
 
I think there is a nice handy-dandy flow chart somewhere around here that is a great reference for bonding bushings. I don't recall where exactly I saw it.
 
lordofthisworld said:
If volts are 250V or higher with eccentric and concentric KO’s.
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Most of the boxes that we use today meet the exception in 250.97 where if the boxed are listed for bonding over 250 volt to ground the bonding bushing isn't required. Disconnect switches and other equipment is another story. :)
 
You never have to use one, but they might be more convenient than other bonding methods. external pipe bonding clamp and external bonding jumper will accomplish the task, but grounding bushing may be preferred over that method.
 
kwired said:
You never have to use one, but they might be more convenient than other bonding methods. external pipe bonding clamp and external bonding jumper will accomplish the task, but grounding bushing may be preferred over that method.
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One could argue that an external bonding jumper with clamp wouldn't comply with 250.92(B) since it's not on the list.
 
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