I have a 400 ' run of 3/4' EMT. It will be a 460 VAC two wire circuit. There are 3 4" square boxes in the run. Do need to install bonding bushings in each of the three boxes?(one on each of the two fittings in each box) or just one bonding bushing at the main breaker panel and one at the panel that this circuit will be feeding? Thank You, Steve Wiese.
How many bonding bushings in run of 3/4" EMT ?
- Thread starter steve61
- Start date
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
Per NEC 250.97 Exception (2), if your boxes don't have "oversized, concentric, or eccentric knockouts," then an EMT connector plus a locknut suffices, no bonding bushings required.
Conversely, any box entry that does have an "oversized, concentric, or eccentric knockout" requires an additional means of bonding, such as a bonding bushing, unless the "concentric or eccentric knockout is listed to provide a reliable bonding connection."
Cheers, Wayne
Conversely, any box entry that does have an "oversized, concentric, or eccentric knockout" requires an additional means of bonding, such as a bonding bushing, unless the "concentric or eccentric knockout is listed to provide a reliable bonding connection."
Cheers, Wayne
- Location
- Illinois
- Occupation
- retired electrician
Is the KO at the main panel clean" (no removable rings remaining? If so, probably none as most 4" square boxes are listed for bonding and grounding 480 volt circuits.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I agree with Don the 1900 boxes do not require bonding bushings so that only leaves the terminations at the ends. If there are full size KO's at the ends than zero bonding bushings are required.