Two Ways A Transformer Can Be Grounded & Bonded

[jar546]

These are both compliant options.
Which option do you see used most often?
Do you see the difference?

Option 1



Option 2

 

[wwhitney]

Those are two ways to ground the secondary side of a transformer as a Separately Derived System (SDS).

When the primary side system is grounded, another option for grounding the secondary side as a non-SDS is by connecting the primary side grounded conductor to one of the secondary conductors. Then no Grounding Electrode Conductor is required, there is no System Bonding Jumper, and the Supply Side Bonding Jumper is just called an EGC.

Just FYI.

Cheers, Wayne

 

[jar546]

Those are two ways to ground the secondary side of a transformer as a Separately Derived System (SDS).

When the primary side system is grounded, another option for grounding the secondary side as a non-SDS is by connecting the primary side grounded conductor to one of the secondary conductors. Then no Grounding Electrode Conductor is required, there is no System Bonding Jumper, and the Supply Side Bonding Jumper is just called an EGC.

Just FYI.

Cheers, Wayne

I agree. Which method do you see used?

 

[chris kennedy]

I use option 1.

 

[jar546]

I use option 1.

That is because Option 1 is the far superior method in most instances.

 

[wwhitney]

That is because Option 1 is the far superior method in most instances.

The only difference is the location of the SBJ and where the GEC terminates. Why is it better to have those at the transformer?

Cheers, Wayne

 

[jar546]

The only difference is the location of the SBJ and where the GEC terminates. Why is it better to have those at the transformer?

Cheers, Wayne

Two reason:
1) It is the most common so you have consistency with inspections (not a big deal)
2) The facility can treat all panelboards as sub-feeds, since the neutral and EGC are separated. Sometimes you can't see the transformer or know that a panelboard is fed by a transformer, so it again, creates consistency. Option two may seem confusing to maintenance staff that does not know better.
3) I prefer it. I'll pass whatever method a contractor uses as long as it is compliant, regardless of my personal preferences.