Ground busing required?

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rookie4now

Senior Member
On a run of EMT from a sub panel to 4 metal 2-gang boxes, where are ground busings required?

It seems logical to me that they are used at the panel because it is painted and might not make a good ground contact. I'm pretty sure I don't need them at each outlet. What is the NEC reference for this?

Thanks
 
K

kevinware

Senior Member
Location
Louisville, KY
Re: Ground busing required?

Rookie4now,
Check out 110.12(c) "Internal parts of electrical equipment including busbars, wiring terminals,insulators, and other surfaces, shall not be damaged or contaminated by foreign materials such as paint, plaster, cleaners, cleaners, abrasives, or corrosive residuse". As far as "Bonding bushings" look at part V. of article 250........And wait to see what others have to say here.....

2005 NEC

[ August 03, 2005, 10:32 AM: Message edited by: kevinware ]
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Re: Ground busing required?

In order to properly answer your question we would need more information starting with the voltage of the conductors entering the boxes and the panel. If the voltage were over 250 volts, we would need to know what type of knockouts the boxes contained. If the voltage were less than 250 volts no bonding bushings would be required.
 
R

rookie4now

Senior Member
Re: Ground busing required?

It is a 120/240 volt system.

It's a little confusing because I've been shown to ALWAYS put a grounding bushing where the service enters the panel. Also, whenever the conduit is used as the EGC, I am supposed to use a grounding bushing at the panel.

I assumed its because the panels are painted and make a poor ground, whereas the boxes down-line are likely to make a solid connection.

Maybe its a company thing. I'll ask today.
 
J

Jhr

Senior Member
Re: Ground busing required?

I'll say this sounds like a branch circuit HR, with maybe some #12-thhn in 3/4" emt.And if it is, I wound say installing grounding bushings is a little overkill :p .
 
J

Jhr

Senior Member
Re: Ground busing required?

By rookie4-now: Well not exactly. Its 3-phase 240 with #10
Click to expand...
Shounld't you be at work its only 12:00 noon in Texas :D As for the bushings I still go with what I posted. See 250.12 :cool:

[ August 04, 2005, 01:02 PM: Message edited by: Jhr ]
 
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