400 A ct cabinet bonding washington/idaho

[Rallyredbull]

Hi all, i am doing a 400a service 277/480. I have a CT can and a meter can next to it the phases including neutral are all stand offs by insulators. Do i need to bond the neutral to the can? or can i bond the neutral to the first point of disconnect (the Main distribution panel) inside the building? I am hearing i need to do both? As in i would bond the neutral with a 1/0 from the neutral CT to a lay in lug in the can? AND i would bond the neutral and groundbar inside the main panel? So this would mean the neutral is bonded at the can AND the first point of disconnect?

I would assume this is just like a transformer AFTER the main point of disconnect, youd use a supply side bonding jumper from the xo terminal to the ground. Brown h1 orange h2 yellow h3 480 primary, black x1 red x2 blue x3 white x0 and a jumper from x0 to ground. Which can be done in the transformer OR the first point of service. But if you do it in the transformer that makes the 120/208 panel a sub panel and grounds neturals are separated.


main question on the can bonding

Is this correct?

 

[paullmullen]

This might be one where your utility will tell you what they want. Often they will have approved metering equipment and that comes configured with everything needed so that all the utility has to do is drop in the meter and the current transformers. If you want to see an example, check out this link. Page D-14 shows approved equipment for a 400A CT connect. Just an example, but the point is that the utility might be your friend here.

 

[david]

Hi all, i am doing a 400a service 277/480. I have a CT can and a meter can next to it the phases including neutral are all stand offs by insulators. Do i need to bond the neutral to the can? or can i bond the neutral to the first point of disconnect (the Main distribution panel) inside the building? I am hearing i need to do both? As in i would bond the neutral with a 1/0 from the neutral CT to a lay in lug in the can? AND i would bond the neutral and groundbar inside the main panel? So this would mean the neutral is bonded at the can AND the first point of disconnect?

I would assume this is just like a transformer AFTER the main point of disconnect, youd use a supply side bonding jumper from the xo terminal to the ground. Brown h1 orange h2 yellow h3 480 primary, black x1 red x2 blue x3 white x0 and a jumper from x0 to ground. Which can be done in the transformer OR the first point of service. But if you do it in the transformer that makes the 120/208 panel a sub panel and grounds neturals are separated.


main question on the can bonding

Is this correct?

The CT cabinet needs bonded..

 

[david]

Hi all, i am doing a 400a service 277/480. I have a CT can and a meter can next to it the phases

including neutral are all stand offs by insulators.

because the neutral is insulated from the ct cabinet enclosure you have options in dealing with parallel neutral current paths even if your using metal conduit

Do i need to bond the neutral to the can?

yes but you can use a ssbj to bond the ct cabinet.

Or you could bond the neutral that is insulated (floating) in the ct cabinet to the ct enclosure

you could install metal conduit with correct bonding bushings and use the conduit as a ssbj and leave the neutral (float) in the ct cabinet.

You could use a wire type ssbj from the service disconnect netral/ eguipment ground buss bar and bond the ct cabinet and leave the neutral (float)

a lot of installations today use pvc conduit and in so doing you do not have the issue of parallel neutral current paths. And do not have conduit bonding concerns.

or can i bond the neutral to the first point of disconnect (the Main distribution panel) inside the building? I am hearing i need to do both?

Yes there also has to be a main bonding jumper at the service disconnect

As in i would bond the neutral with a 1/0 from the neutral CT to a lay in lug in the can? AND i would bond the neutral and groundbar inside the main panel?

that would be one option

So this would mean the neutral is bonded at the can AND the first point of disconnect?

Yes all metal enclosures on the supply side of the overcurrent protection need bonded to the grounded conductor for a service

I would assume this is just like a transformer AFTER the main point of disconnect, youd use a supply side bonding jumper from the xo terminal to the ground.

no, you have a system bonding jumper. At the transformer or the first disconnectbut not both. Exceptions for exterior transformers.
if you bond at the transformer you have a ssbj to the eguipment grounding bussbar in the panel.

And again Metal conduit can be the ssbj or you can use a wire type

Brown h1 orange h2 yellow h3 480 primary, black x1 red x2 blue x3 white x0 and a jumper from x0 to ground. Which can be done in the transformer OR the first point of service.

not actually a service but we know what you ment

But if you do it in the transformer that makes the 120/208 panel a sub panel and grounds neturals are separated.

You also install the grounding electrode conductor where you make the system bonding jumper connection. Every thing is done at the same place as the sbj

main question on the can bonding

Is this correct?

 

[electrofelon]

Hi all, i am doing a 400a service 277/480. I have a CT can and a meter can next to it the phases including neutral are all stand offs by insulators. Do i need to bond the neutral to the can? or can i bond the neutral to the first point of disconnect (the Main distribution panel) inside the building? I am hearing i need to do both? As in i would bond the neutral with a 1/0 from the neutral CT to a lay in lug in the can? AND i would bond the neutral and groundbar inside the main panel? So this would mean the neutral is bonded at the can AND the first point of disconnect?

I would assume this is just like a transformer AFTER the main point of disconnect, youd use a supply side bonding jumper from the xo terminal to the ground. Brown h1 orange h2 yellow h3 480 primary, black x1 red x2 blue x3 white x0 and a jumper from x0 to ground. Which can be done in the transformer OR the first point of service. But if you do it in the transformer that makes the 120/208 panel a sub panel and grounds neturals are separated.


main question on the can bonding

Is this correct?

You are falling into the "one point of bonding" trap. There is no such rule. Everything up to and including the service disconnect gets bonded to the grounded (neutral) conductor. So yes you can have multipile "neutral ground bonds". You do however have the choice of bonding the CT can directly to the grounded conductor in the CT can, or you can run a SSBJ back to the grounded conductor somewhere else, probably the service disconnect. If you by chance are in Seattle, they require the SSBJ and disallow bonding directly to the grounded conductor in the CT can.

 

[Rallyredbull]

You are falling into the "one point of bonding" trap. There is no such rule. Everything up to and including the service disconnect gets bonded to the grounded (neutral) conductor. So yes you can have multipile "neutral ground bonds". You do however have the choice of bonding the CT can directly to the grounded conductor in the CT can, or you can run a SSBJ back to the grounded conductor somewhere else, probably the service disconnect. If you by chance are in Seattle, they require the SSBJ and disallow bonding directly to the grounded conductor in the CT can.

Hi i am in spokane right now and PUD says do not install a SBJ inside the CT can. Do it at the service. So i have a 3/0 from neutral to ground in service and neutral is floating inside CT can. They said they prefer this, so im assuming if this is different per PUD?

In a perfect world id assume i install a system bonding jumper from neutral to the lay in lug in the can. Then also install a MBJ from neutral bar to ground bar at first point of disconnect? All so confusing to me.

I have a transformer also in this building, id assume that "resets" the system? as in creates a separately derived system to the other panel its stepping voltage down to? So id assume id connect a ground from the grounding bar inside transformer to the x0 neutral terminal in the transformer OR in the Panel but not both?

 

[Rallyredbull]

because the neutral is insulated from the ct cabinet enclosure you have options in dealing with parallel neutral current paths even if your using metal conduit

yes but you can use a ssbj to bond the ct cabinet.

Or you could bond the neutral that is insulated (floating) in the ct cabinet to the ct enclosure

you could install metal conduit with correct bonding bushings and use the conduit as a ssbj and leave the neutral (float) in the ct cabinet.

You could use a wire type ssbj from the service disconnect netral/ eguipment ground buss bar and bond the ct cabinet and leave the neutral (float)

a lot of installations today use pvc conduit and in so doing you do not have the issue of parallel neutral current paths. And do not have conduit bonding concerns.

Yes there also has to be a main bonding jumper at the service disconnect

that would be one option

Yes all metal enclosures on the supply side of the overcurrent protection need bonded to the grounded conductor for a service

no, you have a system bonding jumper. At the transformer or the first disconnectbut not both. Exceptions for exterior transformers.
if you bond at the transformer you have a ssbj to the eguipment grounding bussbar in the panel.

And again Metal conduit can be the ssbj or you can use a wire type

not actually a service but we know what you ment

You also install the grounding electrode conductor where you make the system bonding jumper connection. Every thing is done at the same place as the sbj

Thank you much for all the info that is great. This is new to me

 

[electrofelon]

Hi i am in spokane right now and PUD says do not install a SBJ inside the CT can. Do it at the service. So i have a 3/0 from neutral to ground in service and neutral is floating inside CT can. They said they prefer this, so im assuming if this is different per PUD?

In a perfect world id assume i install a system bonding jumper from neutral to the lay in lug in the can. Then also install a MBJ from neutral bar to ground bar at first point of disconnect? All so confusing to me.

I have a transformer also in this building, id assume that "resets" the system? as in creates a separately derived system to the other panel its stepping voltage down to? So id assume id connect a ground from the grounding bar inside transformer to the x0 neutral terminal in the transformer OR in the Panel but not both?

Ok so you do not have a SBJ (at least not at the service). Those are on SDS's. In your service disconnect you have a MBJ. The thing that connects the CT can to the grounded conductor is a SSBJ. You MUST have a SSBJ in the CT can to bond it (unless it's bonded by a raceway with the appropriate service level grounding) all that varies is WHERE it connects to the grounded conductor, IN the CT can or somewhere else like the service disconnect.

 

[david]

Hi i am in spokane right now and PUD says do not install a SBJ inside the CT can. Do it at the service. So i have a 3/0 from neutral to ground in service and neutral is floating inside CT can. They said they prefer this,

It's unclear by what you posted if you being told not to bond the CT cabinet.
If your being told not to bond the CT cabinet by the utility than you need to talk to your electrical inspector

If someone is telling you not to bond the CT cabinet they are wrong

See post #8, you have options on how to bond it, but it must be bonded

 

[electrofelon]

It's unclear by what you posted if you being told not to bond the CT cabinet.
If your being told not to bond the CT cabinet by the utility than you need to talk to your electrical inspector

If someone is telling you not to bond the CT cabinet they are wrong

See post #8, you have options on how to bond it, but it must be bonded

Yeah it's hard to tell with the incorrect terms being used, but I suspect what someone is trying to say is to run a SSBJ from the CT can to the service disconnect instead of making the connection IN the CT can. Either way is okay with the nec, but some utilities may require it a specific way.

 

[rambojoe]

Since the ct enclosure is the utilities baby id just do it their way- myself though im not sure i like another cut and terminated neutral but it doesnt really matter...
Is the meter and short block in the same inclosure?
Oops. Next to it...

 

[david]

Since the ct enclosure is the utilities baby id just do it their way- myself though im not sure i like another cut and terminated neutral but it doesnt really matter...
Is the meter and short block in the same inclosure?
Oops. Next to it...

Here even with the utilities that still provide the ct cabinet the electrician install them and they are inspected by the electrical inspector.the utility preferring something verses mandating something here means two different things.

Even with line voltage metering utilities have a list of sockets that they will except, you just need to know if they are requiring horn bypass or lever bypass sockets.
These choices have some what to do with how you define objectionable current.

No matter what method your using for ct metering, pvc or metal conduit, you can make that bond without creating a parallel neutral current path

 

[electrofelon]

Since the ct enclosure is the utilities baby id just do it their way- myself though im not sure i like another cut and terminated neutral but it doesnt really matter...

Yeah depends on the construction. Some CT mounting bases have a bonding screw like panelboards have. Some have an extra lug on the mounting base you can easily connect the jumper to. If you have neither of these, especially with parallel conductors, it can certainly be annoying to connect the jumper to the neutral there.

 

[rambojoe]

Here even with the utilities that still provide the ct cabinet the electrician install them and they are inspected by the electrical inspector.the utility preferring something verses mandating something here means two different things.

Even with line voltage metering utilities have a list of sockets that they will except, you just need to know if they are requiring horn bypass or lever bypass sockets.
These choices have some what to do with how you define objectionable current.

No matter what method your using for ct metering, pvc or metal conduit, you can make that bond without creating a parallel neutral current path

Ive installed many, just not so many seperate enclosures...pullbox/ct, then meter then main...almost sounds like a older building getting a upgrade.

 

[Rallyredbull]

Here even with the utilities that still provide the ct cabinet the electrician install them and they are inspected by the electrical inspector.the utility preferring something verses mandating something here means two different things.

Even with line voltage metering utilities have a list of sockets that they will except, you just need to know if they are requiring horn bypass or lever bypass sockets.
These choices have some what to do with how you define objectionable current.

No matter what method your using for ct metering, pvc or metal conduit, you can make that bond without creating a parallel neutral current path

I dont undertand the parallel neutral current bath or the objectionable current you're speaking of.

 

[david]

I dont undertand the parallel neutral current bath or the objectionable current you're speaking of.

There are options today when manufacturers of ct cabinets and even some line voltage metering provide a removable bonding link in metering enclosures.

If your supply side bonding is metal conduit or metal conduit was just used as the preferred wiring method and the neutral is factory bonded without a means to unbond it. Normal circuit current would use both the metal conduit path and the neutral wire path during normal conditions.

Anytime current is present on non current caring metal unless its clearing a fault it could be considered objectional current

 

[electrofelon]

There are options today when manufacturers of ct cabinets and even some line voltage metering provide a removable bonding link in metering enclosures.

If your supply side bonding is metal conduit or metal conduit was just used as the preferred wiring method and the neutral is factory bonded without a means to unbond it. Normal circuit current would use both the metal conduit path and the neutral wire path during normal conditions.

Anytime current is present on non current caring metal unless its clearing a fault it could be considered objectional current

In 25 years doing this, I have never seen someone go out of their way to arrange raceway type and bonding jumpers at the service as to avoid objectionable current, nor the objectionable current clause ever questioned or enforced by inspectors.

 

[david]

In 25 years doing this, I have never seen someone go out of their way to arrange raceway type and bonding jumpers at the service as to avoid objectionable current, nor the objectionable current clause ever questioned or enforced by inspectors.

I have seen engineers design with the ssbj returning from the service disconnects

I seen metal conduit with no bond at the ct cabinet, a lot of electricians not realizing the conduit was the ssbj

And we all seen installations with pvc

I'm not trying to make the point, that objectionable currents at a service is an issue.

I have never seen an inspector require a change for that reason
I also do not beleave members here only discuss issues here based on an inspector calling a violation out. I think objectionable current is viewed for the most part kind of like an fine print note (informational note)

 

[electrofelon]

I have seen engineers design with the ssbj returning from the service disconnects

I seen metal conduit with no bond at the ct cabinet, a lot of electricians not realizing the conduit was the ssbj

And we all seen installations with pvc

I'm not trying to make the point, that objectionable currents at a service is an issue.

I have never seen an inspector require a change for that reason
I also do not beleave members here only discuss issues here based on an inspector calling a violation out. I think objectionable current is viewed for the most part kind of like an fine print note (informational note)

I have always thought an inspector is within his/her rights to require a rearrangement of bonding jumpers per 250.6(A)/(B), but never seen or heard of it happening.