What size

[hhsting]

A suggestion:. I understand that if you haven't been an electrician, it's not as easy for you to spot something that is likely to change or that has a zillion different ways it could be installed in the fileld.. but this is one of those things and maybe just provide a general note on the plans saying something like "bonding jumper size and arrangement to be verified at inspection.".

Actually engineer of this project is going to do like attach. He is going to correct it.

Put ground bar outside have GEC taps. Bond trough thru metallic conduit.


Was wondering if bonding jumper from metallic conduit to wire way was required for each service disconnect? Their is supply side bonding jumper inside service disco to metallic conduit. The system is 277/480V three phase. If its required then what size? Also comduit hub acceptable? I thought it had to be grounding bush?

 

[electrofelon]

I like that much better . It is a little bit ambiguous how to size that bonding jumper for each raceway IMO, but i would size it to the conductors in the raceway that is being bonded, so 250.102(C)(2)

 

[electrofelon]

There are several ways to handle the bonding of the nipples to the service disconnects and the trough, but the simplest would be a bonding lock not on each end as long as there are no concentrics. Is this outside? If so then yes you would need the hubs on the bottom side.

 

[hhsting]

There are several ways to handle the bonding of the nipples to the service disconnects and the trough, but the simplest would be a bonding lock not on each end as long as there are no concentrics. Is this outside? If so then yes you would need the hubs on the bottom side.

No this is inside of building in basement. I have SSBJ from neutral bar to conduit hub. Would I need another bonding jumper from conduit to wire way other side of metallic conduit wireway side or one is enough?

 

[electrofelon]

No this is inside of building in basement. I have SSBJ from neutral bar to conduit hub. Would I need another bonding jumper from conduit to wire way other side of metallic conduit wireway side or one is enough?

If you are bonding the wireway thru the nipples and back to the N-G Bond in the service disconnects,. Then you need service bonding on both ends. Follow the fault path from a fault in the wire way back to the main bonding jumper in the service disconnects. That path has to have service bonding as described in 250.92. Again, the simplest would just be a bonding lock nut on each end. I'm not sure why one would use a myer's hub on top of the disconnect, but you could.

Again, I would just make a markup on the plans saying wireways and nipples to be bonded per 250.92 and let the inspector approve or disprove it on inspection.

 

[hhsting]

If you are bonding the wireway thru the nipples and back to the N-G Bond in the service disconnects,. Then you need service bonding on both ends. Follow the fault path from a fault in the wire way back to the main bonding jumper in the service disconnects. That path has to have service bonding as described in 250.92. Again, the simplest would just be a bonding lock nut on each end. I'm not sure why one would use a myer's hub on top of the disconnect, but you could.

Again, I would just make a markup on the plans saying wireways and nipples to be bonded per 250.92 and let the inspector approve or disprove it on inspection.

Would not conduit hub do the bonding of wireway thru nipples thru bonding jumper? I am just curious?

 

[infinity]

Would not conduit hub do the bonding of wireway thru nipples thru bonding jumper? I am just curious?

If you have a hub on either end of the service raceway no bonding jumpers are required.
In post #21 what is the single conductor that you're showing in the raceway?

 

[hhsting]

If you have a hub on either end of the service raceway no bonding jumpers are required.
In post #21 what is the single conductor that you're showing in the raceway?

Those are the phase and neutral conductors from service CT cabinet. The single conductor is the neutral going from CT cabinet to bar in service disco. So I can use conduit hub and thats the only thing required?

 

[infinity]

Those are the phase and neutral conductors from service CT cabinet. The single conductor is the neutral going from CT cabinet to bar in service disco. So I can use conduit hub and thats the only thing required?

Look at 250.92(B) and the 4 approved bonding methods for service raceways. A hub is one of them.

 

[hhsting]

What code section one uses to bond the bonding jumper to the wireway? What kind of connector would this be?

 

[infinity]

What code section one uses to bond the bonding jumper to the wireway? What kind of connector would this be?

Can you be more specific which bonding jumper? How is the wireway connected to the CT cabinet?

 

[electrofelon]

The wireway is on the line side of the service disconnects so I'm thinking that the service conductors feeding the CT cabinet would be used to determine the bonding jumper size.

So let's say the total kcmil area of the conductors in the wire way (load side of CT to disconnects) are 3,600 kcmil, but say the total kcmil on the line side if the CT is larger, let's just say it's 5,000. Does a jumper used to bond the wire way get sized to the 3,600 or the 5,000? It's entirely clear to me that we use the largest size of any conductor set in the system.

 

[infinity]

So let's say the total kcmil area of the conductors in the wire way (load side of CT to disconnects) are 3,600 kcmil, but say the total kcmil on the line side if the CT is larger, let's just say it's 5,000. Does a jumper used to bond the wire way get sized to the 3,600 or the 5,000? It's entirely clear to me that we use the largest size of any conductor set in the system.

It's based on the line side of the CT's not the total of the service conductors feeding the disconnects. If you were using bonding jumper taps to the GEC for each switch that GEC would also be sized according to the SEC's feeding the CT cabinet.

 

[hhsting]

Can you be more specific which bonding jumper? How is the wireway connected to the CT cabinet?

Please see post #21 sketch. In that sketch the wireway I have three bonding jumper from each if the three metallic conduits to the wireway enclosure. Thats the bonding jumpers I am referring to.

I have sized each of them based on incoming service conductors from wireway into metallic conduit to service discos neutral bar. What connectors one uses to connect them to the wire way enclosure?

 

[electrofelon]

Please see post #21 sketch. In that sketch the wireway I have three bonding jumper from each if the three metallic conduits to the wireway enclosure. Thats the bonding jumpers I am referring to.

I have sized each of them based on incoming service conductors from wireway into metallic conduit to service discos neutral bar. What connectors one uses to connect them to the wire way enclosure?

I gave my opinion in post #22. 250.102 needs some work and doesn't appear to cover that situation specifically.

 

[electrofelon]

It's based on the line side of the CT's not the total of the service conductors feeding the disconnects. If you were using bonding jumper taps to the GEC for each switch that GEC would also be sized according to the SEC's feeding the CT cabinet.

Im Not sure. I see your point, but on the other hand 250.102(C) allows sizing based on the conductors within. 250.102 needs some work. It doesn't cover the nipples in the OP nor how to parallel SSBJ's routed THRU raceways.

 

[hhsting]

Im Not sure. I see your point, but on the other hand 250.102(C) allows sizing based on the conductors within. 250.102 needs some work. It doesn't cover the nipples in the OP nor how to parallel SSBJ's routed THRU raceways.

Excuse me but doesnt 250.102(c)(2) cover parallel conductors install two or more raceways?

I don’t see how to size supply conductors for sets of conductors. Set include single or parallel

 

[electrofelon]

Excuse me but doesnt 250.102(c)(2) cover parallel conductors install two or more raceways?

Yes correct.

I don’t see how to size supply conductors for sets of conductors. Set include single or parallel

Yes I agree it is a little ambiguous.