bonding bushing on Line/Load of transformer
- Thread starter screamer
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- Location
- Bremerton, Washington
Re: bonding bushing on Line/Load of transformer
It depends the fitting and the wire size. The fitting may not require an insulating bushing by its design. Insulated bushings are required for conductors 4 AWG and larger see section 300.4(F)
I seldom use metal insulating bushings, for your application I would use a insulating bushing, as the transformer would vibrate and could damage the wires.
It depends the fitting and the wire size. The fitting may not require an insulating bushing by its design. Insulated bushings are required for conductors 4 AWG and larger see section 300.4(F)
I seldom use metal insulating bushings, for your application I would use a insulating bushing, as the transformer would vibrate and could damage the wires.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: bonding bushing on Line/Load of transformer
300.4 is only required where a raceway enters a enclosure. A fitting for FMC is not a raceway. The only raceway to me that would enter an enclosure would be of the threaded types. But as Tom stated the vibration would warrent an insulated bushing. As for requiring a grounding bushing? why FMC would not be allowed to be used as the EGC as it would only have a 60 amp rating and this transformer would have a fault current of over 400 amps. It would serve no purpose.
300.4 is only required where a raceway enters a enclosure. A fitting for FMC is not a raceway. The only raceway to me that would enter an enclosure would be of the threaded types. But as Tom stated the vibration would warrent an insulated bushing. As for requiring a grounding bushing? why FMC would not be allowed to be used as the EGC as it would only have a 60 amp rating and this transformer would have a fault current of over 400 amps. It would serve no purpose.
- Location
- Massachusetts
Re: bonding bushing on Line/Load of transformer
EMT, FMC, LFMC, etc. all require bushings when used with conductors of 4 AWG or larger, or fittings with built in insulating matrial.
IMO you are reading to much into the word "entering".
I would fail inspection here in my area if I did not use bushings on EMT or FMC with 4 AWG or larger.
If you where writing that section of code what word would you use in place of 'entering'?
[ December 31, 2004, 05:50 AM: Message edited by: iwire ]
Wayne you and I differ on 300.4, IMO any raceway that connects to a enclosure with 4 AWG or larger requires a bushing.
EMT, FMC, LFMC, etc. all require bushings when used with conductors of 4 AWG or larger, or fittings with built in insulating matrial.
IMO you are reading to much into the word "entering".
I would fail inspection here in my area if I did not use bushings on EMT or FMC with 4 AWG or larger.
If you where writing that section of code what word would you use in place of 'entering'?
Bob
[ December 31, 2004, 05:50 AM: Message edited by: iwire ]
- Location
- Massachusetts
Re: bonding bushing on Line/Load of transformer
Stephen
In that case I can not give you a yes or no answer, all I can say is maybe.
You will have to look at 250.97 and decide if you need bonding bushings or not.
On the primary side you have over 250 volts to ground, that being the case you would have to use bonding bushings around a concentric knock out if it is not listed for that purpose.
Stephen
In that case I can not give you a yes or no answer, all I can say is maybe.
You will have to look at 250.97 and decide if you need bonding bushings or not.
On the primary side you have over 250 volts to ground, that being the case you would have to use bonding bushings around a concentric knock out if it is not listed for that purpose.
Re: bonding bushing on Line/Load of transformer
screamer,I've been digging at this,and what I've finally come up with is:
250.118(6)
Listed flexible metal conduit,that is "NOT" listed for grounding,meeting -"ALL"- the following conditions.(must meet all),including "d" field-installing a EGC,still might not meet the needs.Parallel path for fault current might still exsist.See 250.96 also..I'm not sure this covers your question, 100% and is open for debate.And yes,I seen 250.97 also..
screamer,I've been digging at this,and what I've finally come up with is:
250.118(6)
Listed flexible metal conduit,that is "NOT" listed for grounding,meeting -"ALL"- the following conditions.(must meet all),including "d" field-installing a EGC,still might not meet the needs.Parallel path for fault current might still exsist.See 250.96 also..I'm not sure this covers your question, 100% and is open for debate.And yes,I seen 250.97 also..
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: bonding bushing on Line/Load of transformer
Bob you must have changed your view on this as you posted this when I had this question back in October :
Bob you must have changed your view on this as you posted this when I had this question back in October :
I agree it need's one because of the vibration from a transformer, but most fittings I have seen have a well rounded throat? As Dave (Websparky) has said it is a poorly written section.
- Location
- Massachusetts
Re: bonding bushing on Line/Load of transformer
That thread was about SE cable which is not a raceway.
My reply in this thread was regarding FMC which is a raceway.
Bob
No, same view.
That thread was about SE cable which is not a raceway.
My reply in this thread was regarding FMC which is a raceway.
Bob
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: bonding bushing on Line/Load of transformer
Sorry I haven't posted lately been real busy.
I'm now seeing what your saying and it does make sense. Which would back the reason insulated bushings are needed in the first place.
What was confusing me was in the exception where is says;
which was leading me to belive that it was meaning a fitting that was allowed to be the exception?
Sorry I haven't posted lately been real busy.
I'm now seeing what your saying and it does make sense. Which would back the reason insulated bushings are needed in the first place.
What was confusing me was in the exception where is says;
I can't think of a hub or a boss that would be a part of a raceway?
which was leading me to belive that it was meaning a fitting that was allowed to be the exception?
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