PLASTIC BUSHING AND GROUNDING BUSHINGS
- Thread starter manny
- Start date
- Status
russ
Senior Member
- Location
- Burbank IL
Re: PLASTIC BUSHING AND GROUNDING BUSHINGS
300.4(F) and 250.92(B)
Russ
300.4(F) and 250.92(B)
Russ
goldstar
Senior Member
- Location
- New Jersey
- Occupation
- Electrical Contractor
Re: PLASTIC BUSHING AND GROUNDING BUSHINGS
As Russ pointed out 300.4(f) and 250.92(b) are the correct sections for this. Bear in mind (with respect to 300.4(f) when you're using a manufactured connector where the edge of the fitting is flared or rounded (i.e a 2" squeeze connector for SEU cable)you don't need a fiber or plastic bushing. If it's threaded conduit entering directly into the enclosure...you do.
Also, (with respect to 250.92(b)a bonding locknut or bushing is required if you have concentric knockouts because it is possible that the integrity of the metal parts between the enclosure and the knockout layers can become separated either at the time of installation or over time from vibration.
Hope this helps.
As Russ pointed out 300.4(f) and 250.92(b) are the correct sections for this. Bear in mind (with respect to 300.4(f) when you're using a manufactured connector where the edge of the fitting is flared or rounded (i.e a 2" squeeze connector for SEU cable)you don't need a fiber or plastic bushing. If it's threaded conduit entering directly into the enclosure...you do.
Also, (with respect to 250.92(b)a bonding locknut or bushing is required if you have concentric knockouts because it is possible that the integrity of the metal parts between the enclosure and the knockout layers can become separated either at the time of installation or over time from vibration.
Hope this helps.
- Location
- Massachusetts
Re: PLASTIC BUSHING AND GROUNDING BUSHINGS
Goldstar,
300.4(F) states "smoothly rounded insulating surface" So a 2" squeeze connector for SEU cable would need a plastic bushing.
Unless coming in thru a hub, but the normally the conector will need a bushing.
[ March 02, 2003, 09:05 AM: Message edited by: iwire ]
Goldstar,
300.4(F) states "smoothly rounded insulating surface" So a 2" squeeze connector for SEU cable would need a plastic bushing.
Unless coming in thru a hub, but the normally the conector will need a bushing.
[ March 02, 2003, 09:05 AM: Message edited by: iwire ]
curt swartz
Electrical Contractor - San Jose, CA
- Location
- San Jose, CA
- Occupation
- Electrical Contractor
Re: PLASTIC BUSHING AND GROUNDING BUSHINGS
300.4(F) Where raceways containing ungrounded conductors 4AWG or larger enter a cabinet, box enclosure............
It only specifies raceways and doesn't say anything about cables.
300.4(F) Where raceways containing ungrounded conductors 4AWG or larger enter a cabinet, box enclosure............
It only specifies raceways and doesn't say anything about cables.
- Location
- Massachusetts
Re: PLASTIC BUSHING AND GROUNDING BUSHINGS
curt Yes, you are right I overlooked that.
I have always put bushings on conductors #4 and larger and thought it was the code.
curt Yes, you are right I overlooked that.
I have always put bushings on conductors #4 and larger and thought it was the code.
goldstar
Senior Member
- Location
- New Jersey
- Occupation
- Electrical Contractor
Re: PLASTIC BUSHING AND GROUNDING BUSHINGS
Bob (iwire),
I used to use plastic bushings on all squeeze connectors. Someone also once told me that on all connectors 2" and above it was mandatory. However, if you look closely at the 2" SEU squeeze connector it does have a rounded edge and cannot cut into the wire. I haven't used plastic bushings in several years now nor have any of my collegues in the contractors' association and I haven't failed an inspection.
The next service upgrade I do I'll ask the inspector and get an opinion from him. If I find out differently I'll post it.
Regards,
Phil Bufis
Gold Star Electric
Ringwood, NJ
Bob (iwire),
I used to use plastic bushings on all squeeze connectors. Someone also once told me that on all connectors 2" and above it was mandatory. However, if you look closely at the 2" SEU squeeze connector it does have a rounded edge and cannot cut into the wire. I haven't used plastic bushings in several years now nor have any of my collegues in the contractors' association and I haven't failed an inspection.
The next service upgrade I do I'll ask the inspector and get an opinion from him. If I find out differently I'll post it.
Regards,
Phil Bufis
Gold Star Electric
Ringwood, NJ
Re: PLASTIC BUSHING AND GROUNDING BUSHINGS
I think the issue of conduit size must have been in the code at one time. When I was a cub I was taught conduits 1-1/4? and larger required bushings. The fact is it is biased on a conductor size of #4 and larger. You can have a 4? conduit with number 6 AWG wire and not need a bushing if you have connectors with smooth rounded edges such as EMT connectors.
I think the issue of conduit size must have been in the code at one time. When I was a cub I was taught conduits 1-1/4? and larger required bushings. The fact is it is biased on a conductor size of #4 and larger. You can have a 4? conduit with number 6 AWG wire and not need a bushing if you have connectors with smooth rounded edges such as EMT connectors.
michael nye
Member
- Location
- California
Re: PLASTIC BUSHING AND GROUNDING BUSHINGS
the Code is again the minimum any craftsman would put bushings on everything, its just good practice.
the Code is again the minimum any craftsman would put bushings on everything, its just good practice.
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