Need for a gnd conductor

[shockin]

I have a fire pump that will be fed from the utility transformer. The pump is located 500' away. The pump is 3 phase 480 volt (no neutral of course). Do I need to pull a ground conductor as well in this conduit or just the 3 hots? If I do pull a ground what would I do with it the the transformer? Tie it to the ulitities ground rod?

Does 2008NEC 250.4 (A) (5) apply?

Thanks

 

[raider1]

Take a look at 250.112(L)

Chris

 

[shockin]

Chris -

I would agree that it needs to be bonded. My question would be, do I need to pull a ground from the xfmr, or can I view it as a service as install a ground rod at the service disconnect for the fire pump?

Thanks

 

[pete m.]

Is the utility transformer a grounded system? possibly 208Y120 or 480Y277?

Pete

 

[shockin]

The xfmr is grounded. 480/277.

 

[augie47]

In that caSE 250.24(c) applies. A groundED conductor must be installed.

 

[shockin]

That confuses me. (not too hard to do). You say a groundED conductor must be installed. Would you mean a grounding conductor instead?

 

[raider1]

Where is the service disconnecting means for this installation?

Chris

 

[shockin]

The service disconnecting means is part of the fire pump controller which is next to the fire pump. 500' from the transformer.

 

[skeshesh]

That confuses me. (not too hard to do). You say a groundED conductor must be installed. Would you mean a grounding conductor instead?

Yea I think he means a grounding conductor since we're talkin about equipment ground. You don't need a Neutral run.

 

[raider1]

The service disconnecting means is part of the fire pump controller which is next to the fire pump. 500' from the transformer.

Then you will need to bring a grounded conductor with the service conductors from the utility transformer to the fire pump controller/ service disconnecting means. Take a look at 250.24(C) as Augie pointed out earlier.

Chris

 

[raider1]

Yea I think he means a grounding conductor since we're talkin about equipment ground. You don't need a Neutral run.

Actually, where what we are talking about is service conductors, then you do need to bring a groundED conductor to the service disconnecting means. (See 250.24(C))

Chris

 

[augie47]

Yea I think he means a grounding conductor
.

No "he" doesn't , He means what 250.24(C) states:
(C) Grounded Conductor Brought to Service Equipment. Where an ac system operating at less than 1000 volts is grounded at any point, the grounded conductor(s) shall be run to each service disconnecting means and shall be connected to each disconnecting means grounded conductor(s) terminal or bus. A main bonding jumper shall connect the grounded conductor(s) to each service disconnecting means enclosure. The grounded conductor(s) shall be installed in accordance with 250.24(C)(1) through (C)(3).

since we're talkin about equipment ground. You don't need a Neutral run.

This grounded conductor is size per 250.66 and as noted there is a main bonding jumper at which time the grounding conductors connect to this required ground. You may look at it as a grounding conductor as it carries fault currents to the source, but by Code it's a grounded conductor.

 

[skeshesh]

I'm wrong

I'm wrong

Actually, where what we are talking about is service conductors, then you do need to bring a groundED conductor to the service disconnecting means. (See 250.24(C))

You guys are right. This is absolutely necessary to complete the ground fault path. Good one, I can't believe I overlooked this. I'm becoming absolutely addicted to this forum. :grin:

 

[raider1]

I'm becoming absolutely addicted to this forum.

Maybe we need to start a clinic to cure us forum addicts.

P.S. my wife has talked about stating a "wives of Mike Holt forum members" support group.

Chris

 

[augie47]

Maybe we need to start a clinic to cure us forum addicts.

P.S. my wife has talked about stating a "wives of Mike Holt forum members" support group.

Chris

I am looking at a charter member just across the room from me.

 

[skeshesh]

Hilarious

Hilarious

Still a bit young to get married:roll: But I seriously wish I knew about this site when I was still in school. They should require electrical engineering students (at least the guys studying power like I did) to do 6 months of field work with a contractor or something like that. Now I'm a bit more knowledgable, but when I graduated a few years ago I didn't know crap about practical stuff and it was a huge pain in the neck to learn all that stuff.

 

[shockin]

Just to confirm - The need for running the ground conductor is due to the lack of a neutral. Had a neutral been present the ground would not have been required. Correct?

 

[raider1]

Just to confirm - The need for running the ground conductor is due to the lack of a neutral. Had a neutral been present the ground would not have been required. Correct?

On the line side of the service disconnecting means the grounded conductor is used for the effective fault current path. On the load side of the service disconnecting means the equipment grounding conductor is used for the effective fault current path. Hope this makes sense.

Chris

 

[skeshesh]

Grounding

Grounding

I don't think so. The neutral is supposed to not carry any current (of course it does because of unbalanced loads) and it's sized to carry short circuit current. The grounding conductor is for equipment grounding.

Edit: I don't think so referring to shockin not raider1