Dry Type Transf to Panel Grounding

[Elvin]

The grounding (bonding) conductor from a separately derived system (dry type transf. which has the GEC bonded to XO at the transf) to the panel (first disconnect) - isn't this a system bonding jumper (per 250.30 (A) (1) )? And as such shoudn't it be sized based on 250.28(D)?

I have looked through all my emails and your archives and found a picture from 'Grounding vs Bonding Online Training 18' that indicates the system bonding jumper from the XO to the grounding terminal attached to the transf, but it doesn't clarify from the transf to the panel. There may be another picture elsewhere but I have not found it.

What I have found and what I have been basing my belief on is the 1999 NEC Handbook, Figure 250.12A, that does show a "Main Bonding Jumper" from the transf to the first disconnect.

What do you think?

 

[infinity]

It would be a system bonding jumper and sized according to 250.66. As you've stated, look at 250.30(A)(1).

 

[raider1]

The grounding (bonding) conductor from a separately derived system (dry type transf. which has the GEC bonded to XO at the transf) to the panel (first disconnect) - isn't this a system bonding jumper (per 250.30 (A) (1) )?

If you have your system bonding jumper at the transformer then the bonding conductor between the transformer and the panel would be an equipment bonding jumper as stated in 250.30(A)(2) and be sized in accordance with 250.102(C). (This would still be sized from table 250.66 though)

Chris

 

[infinity]

If you have your system bonding jumper at the transformer then the bonding conductor between the transformer and the panel would be an equipment bonding jumper as stated in 250.30(A)(2) and be sized in accordance with 250.102(C). (This would still be sized from table 250.66 though)

Chris

You have it backwards. If the neutral is bonded at the transformer (this would be the equipment bonding jumper) the grounding conductor between the transformer and the panel would be the system bonding jumper.

 

[Bea]

You have it backwards. If the neutral is bonded at the transformer (this would be the equipment bonding jumper) the grounding conductor between the transformer and the panel would be the system bonding jumper.

It depends on where the GEC is landed both of your statements could be correct neither has said where GEC is connect unless you are referening the bond of neutral as that connection piont as the OP has stated if so raider has it correctly stated.

 

[infinity]

It depends on where the GEC is landed both of your statements could be correct neither has said where GEC is connect unless you are referening the bond of neutral as that connection piont as the OP has stated if so raider has it correctly stated.

I'm basing my answer on what it said in the OP, here is what it said:

a separately derived system (dry type transf. which has the GEC bonded to XO at the transf)

I'm not assuming, since the requirement is that the GEC connection and the bonding jumper are required to be made at the same place. This is from the 2005 NECH:

The location of the grounding electrode conductor connection to the grounded conductor must be at the same point as where the connection of the bonding jumper is connected to the grounded conductor.

 

[raider1]

Here is the definition of a system bonding jumper:

Bonding jumper, System. The connection between the grounded circuit conductor and the equipment grounding conductor at a separately derived system.

So I guess what we need to find out is where the bonding conductor between the transformer and the panel is landed. If the bonding conductor terminates at the case of the transformer and connects to the equipment grounding terminal at the panel then it would be a equipment bonding jumper as stated in 250.30(A)(2).

Is there a system bonding jumper from the XO terminal of the transformer to the case of the transformer?

Really this is an excersize in terminology, because both conductors (system bonding jumpers and equipment bonding jumpers) as related to separately derived systems are sized off 250.66 based on the size of the derived secondary conductors.

Chris

 

[infinity]

I agree this is mainly semantics, but the OP said that the GEC went to the transformer so the equipment bonding jumper is required to be there also.

 

[Bea]

I agree this is mainly semantics, but the OP said that the GEC went to the transformer so the equipment bonding jumper is required to be there also.

I will agree for simplicity and not to confuse but it is not the only way. Also it is the system bonding jumper.

From the transformer to the first system disconnect you could install a equipment bonding jumper in which case you would float the nuetrals from equipment grounds taking the equipment bonding jumper to the equipment grounds which are bonded to enclosure of first system disconnect.

Hope I have stated this clearly.

 

[infinity]

I will agree for simplicity and not to confuse but it is not the only way. Also it is the system bonding jumper.

From the transformer to the first system disconnect you could install a equipment bonding jumper in which case you would float the nuetrals from equipment grounds taking the equipment bonding jumper to the equipment grounds which are bonded to enclosure of first system disconnect.

Hope I have stated this clearly.

You did. And you're correct there is more than one way to do this. If the GEC goes to the transformer than the equipment boding jumper will connect the transformer case to the grounded conductor there and the system bonding jumper will go to the panel as mentioned in the OP.