Bonding neutral and ground at service end box in NYC

[Tainted]

I usually see all service switch neutrals grounded to the ground bus in the room. Ground bus is bonded to ground rods with building steal, water main, etc.

Are you allowed to bond ground and neutral at the service end box instead of service switches? Not sure if this is ok in NYC

If you bond the neutral and ground at the service end box, does this mean you don't have to bond ground and neutral at the service switches?

 

[LarryFine]

If you bond sooner, you have to run separate EGCs and wire everything as you would feeders and sub-panels.

Unless this 'service end box' is in/on a separate structure.

 

[Tainted]

If you bond sooner, you have to run a separate EGC and wire everything as you would feeders and sub-panels.

yea... but you can just use conduit as a EGC

 

[LarryFine]

yea... but you can just use conduit as a EGC

True, if that's what is used. I'm not familiar with the term 'service end box'.

 

[Tainted]

True, if that's what is used. I'm not familiar with the term 'service end box'.

It's a term widely used in NYC electrical industry. It's basically just a box with copper bus inside that Con-Edison wires terminate to.

 

[Fred B]

I usually see all service switch neutrals grounded to the ground bus in the room. Ground bus is bonded to ground rods with building steal, water main, etc.

Are you allowed to bond ground and neutral at the service end box instead of service switches? Not sure if this is ok in NYC

If you bond the neutral and ground at the service end box, does this mean you don't have to bond ground and neutral at the service switches?

Not sure if the language is present in the NYC code But,
2017 NEC 250.24(A)(1)
(1) General.
The grounding electrode conductor connection shall be made at any accessible point from the load end of the overhead service conductors, service drop, underground service conductors, or service lateral to, including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.

A busway would meet requirement as a potential location for connection. That doesn't change the location for Bonding related to the "First overcurrent Device".
This is a frequently discussed issue created by language and "what is" Grounded, Grounding, Bonding, GEC, GES, EGC, etc. and the locations of each.

 

[infinity]

Are you allowed to bond ground and neutral at the service end box instead of service switches? Not sure if this is ok in NYC

No. The MBJ has to be in the location of the service disconnect(s). The neutral should also be bonded in the end box.

 

[Tainted]

No. The MBJ has to be in the location of the service disconnect(s). The neutral should also be bonded in the end box.

So what you're saying is we should have 2 forms of main bonding jumpers?

If you have a main bonding jumper inside the service end box

and also have main bonding jumper inside the service switches

wouldn't the neutral current go travel to the raceway and the neutral wire creating parallel paths between the end box and service switch?

 

[electrofelon]

No. The MBJ has to be in the location of the service disconnect(s). The neutral should also be bonded in the end box.

So what you're saying is we should have 2 forms of main bonding jumpers?

If you have a main bonding jumper inside the service end box

and also have main bonding jumper inside the service switches

wouldn't the neutral current go travel to the raceway and the neutral wire creating parallel paths between the end box and service switch?

View attachment 2569815

What I usually say is although there is technically only one MBJ (or one per service disconnect rather), there are other jumpers ahead of that that are doing this essentially the same thing but are called something different. Those are supply side bonding jumpers. Yes, parallel paths are very common and accepted on services.

 

[Tainted]

What I usually say is although there is technically only one MBJ (or one per service disconnect rather), there are other jumpers ahead of that that are doing this essentially the same thing but are called something different. Those are supply side bonding jumpers. Yes, parallel paths are very common and accepted on services.

Hold on a second... How and why are they accepted on services if there is objectional current? isn't objectional current forbidden by code?

 

[electrofelon]

Hold on a second... How and why are they accepted on services if there is objectional current? isn't objectional current forbidden by code?

Yes objectionable current is prohibited, but they never define it or say what is considered objectionable. It is often unavoidable on services.

 

[infinity]

Yes there is only one main bonding jumper and that is in the service disconnect. All other metal parts upstream of the MBJ are bonded directly to the neutral. The upstream bonding is required to prevent the metal parts from becoming energized.

Objectionable current must be mitigated when possible but with services some types of objectionable current, like flowing on metal raceways, is unavoidable.

 

[electrofelon]

Objectionable current must be mitigated when possible but with services some types of objectionable current, like flowing on metal raceways, is unavoidable.

My reading of 250.6 is that an inspector would be within his rights to require remediations such rearranging SSBJ's to a central location, using a nonmetallic fitting or raceway, etc, but I have not once heard of anyone actually requiring this or caring about it.

 

[texie]

Yes there is only one main bonding jumper and that is in the service disconnect. All other metal parts upstream of the MBJ are bonded directly to the neutral. The upstream bonding is required to prevent the metal parts from becoming energized.

Objectionable current must be mitigated when possible but with services some types of objectionable current, like flowing on metal raceways, is unavoidable.

Well said. I would also suggest the OP look at 250.92.

 

[infinity]

My reading of 250.6 is that an inspector would be within his rights to require remediations such rearranging SSBJ's to a central location, using a nonmetallic fitting or raceway, etc, but I have not once heard of anyone actually requiring this or caring about it.

Since metallic raceways are included in the list of acceptable service raceways in Article 230 I see no way someone could reject using one even if it it caused objectionable current.

Metal raceways have been around for many decades longer than non-metallic raceways and have always allowed objectionable current so I don't see an issue with using them. But to your point if all objectional must be mitigated then metal raceways would need to be banned for service conductors.

 

[electrofelon]

Since metallic raceways are included in the list of acceptable service raceways in Article 230 I see no way someone could reject using one even if it it caused objectionable current.

Metal raceways have been around for many decades longer than non-metallic raceways and have always allowed objectionable current so I don't see an issue with using them. But to your point if all objectional must be mitigated then metal raceways would need to be banned for service conductors.

I do agree it would be a bit extreme for an inspector to say "replace those with NM raceways". What about rearranging bonding jumpers? That doesn't seem as unreasonable.

 

[LarryFine]

It's a term widely used in NYC electrical industry. It's basically just a box with copper bus inside that Con-Edison wires terminate to.

Are they internal or external to the premises?

 

[LarryFine]

No. The MBJ has to be in the location of the service disconnect(s). The neutral should also be bonded in the end box.

None of which requires an EGC, correct?

 

[infinity]

Are they internal or external to the premises?

Inside. Typically fed directly from the vault outside.

 

[LarryFine]

So what you're saying is we should have 2 forms of main bonding jumpers?

If you have a main bonding jumper inside the service end box

and also have main bonding jumper inside the service switches

wouldn't the neutral current go travel to the raceway and the neutral wire creating parallel paths between the end box and service switch?

View attachment 2569815

Your examples show feeders, not service conductors.