Grounding a guard shack supplied by a feeder

[main197]

We have a 16'x7.5' guard shack that will be supplied by a feeder. The feeder goes into a 480V-120/240V single phase transformer and then into a 125A panel. What are the grounding and bonding requirements?

 

[zbang]

Same as any other structure unless there's some special situation.

 

[augie47]

250.32 for the building, 250.30 for the transformer.

 

[main197]

250.32 for the building, 250.30 for the transformer.

If I am understanding this correctly, I will need a grounding electrode both at the transformer and at the panel?

 

[petersonra]

If I am understanding this correctly, I will need a grounding electrode both at the transformer and at the panel?

Potentially it could be the same grounding electrode(s).

 

[LarryFine]

If I am understanding this correctly, I will need a grounding electrode both at the transformer and at the panel?

How far apart are they? If in one structure, only one electrode system is needed, land in one or the other.

If you have separate structures and electrode systems for each one, only earth may interconnect them.

 

[tom baker]

250.30 and 32 are well written. I would suggest you review and comeback with questions.

 

[Dsg319]

Even if his transformer is remote from the guard shack. If he’s has his main bonding jumper installed the the panel and not the transformer, can he get away with just the grounding electrode at the shack?

 

[LarryFine]

Even if his transformer is remote from the guard shack. If he’s has his main bonding jumper installed the the panel and not the transformer, can he get away with just the grounding electrode at the shack?

I don't believe so.

 

[Dsg319]

I don't believe so.

I wasn’t sure I need to brush up in this area myself. So if the transformer is say 100’ from shack he’s stuck with having grounding electrode system there and his guard shack.

 

[zbang]

Not a big deal- 2 rods and maybe 10' of #6 vs 4 rods and 20'.

 

[don_resqcapt19]

I wasn’t sure I need to brush up in this area myself. So if the transformer is say 100’ from shack he’s stuck with having grounding electrode system there and his guard shack.

See 250.30(C).

 

[LarryFine]

I wasn’t sure I need to brush up in this area myself. So if the transformer is say 100’ from shack he’s stuck with having grounding electrode system there and his guard shack.

Why would you think so, and why would you think not?

 

[Dsg319]

Why would you think so, and why would you think not?

WelI I believe you would have to have one at both places. Since your required to have one at the source of the SDS and a separate structure also needs a GES.

 

[LarryFine]

WelI I believe you would have to have one at both places. Since your required to have one at the source of the SDS and a separate structure also needs a GES.

Exactamundo!

 

[electrofelon]

Exactamundo!

But is there anything that says you can't double dip on a single set of electrodes for each thing that has a grounding requirement?

 

[LarryFine]

But is there anything that says you can't double dip on a single set of electrodes for each thing that has a grounding requirement?

Not at all. Any electrodes that are close enough to tie together should be tied together . . . except when doing so would directly (not through earth) tie two different points of the neutral conductor together.