Does 250.32 apply?

[charlie b]

I am separating this issue from a previous thread of mine. Consider the following:
? Pour a small concrete pad (3? x 5?), some distance away from a building.
? Place on the pad a manufactured skid that includes a couple pumps and some valves, pipes, and motor controllers.
? Provide power to the skid via a single branch circuit from the nearby building.

Question 1: Does this meet the definition of ?structure,? per NEC article 100?

Question 2: If the answer to #1 is ?yes,? then do the requirements of NEC 250.32 apply (i.e., is a grounding electrode required)?

For my part, I have never installed ground rods near skid-mounted water processing equipment. But the equipment has always been inside the same building as the source of power. So this is a new territory for me.

 

[bphgravity]

Answer 1: YES. This is a structure.

Answer 2: Yes. 250.32 does apply BUT you indicate a signle branch circuit is supplying this separate structure, thus the exception can be applied.

Exception: A grounding electrode shall not be required
where only a single branch circuit, including a multiwire
branch circuit, supplies the building or structure and the
branch circuit includes an equipment grounding conductor
for grounding the normally non?current-carrying metal
parts of equipment.

In the event a feeder were to be installed to this separate structure, a GES would be required. (Even though it is a silly requirement)

 

[renosteinke]

I don't think a pile of equipment sitting on an open pad constitutes a 'structure.' Do we treat, say, pool equipment this way?

I'd even say a protective fence isn't enough to make it a structure- you need a roof.

 

[Dennis Alwon]

If it is a single branch circuit then no electrode is needed. 250.32 exception but I would call it a structure.

 

[petersonra]

I think it is likely a structure by the defintion of structure in article 100. Someone built it.

Structure. That which is built or constructed.

One might argue that it was manufactured as opposed to being built or constructed. I think that could be a good argument for the skid, but the concrete pad is harder to make that argument about.

If there is but one BC going to it, IMO it is a moot point.

However, if it is underground metal pipe, the pipe may require bonding to the existing GES.

Just out of curiousity, if you decided it needed a GES at the skid, just what would you bond the rod(s) to?

 

[iwire]

I don't think a pile of equipment sitting on an open pad constitutes a 'structure.'

IMO it is, please see article 100 defintion of a structure.

Do we treat, say, pool equipment this way?

We should.

I'd even say a protective fence isn't enough to make it a structure- you need a roof.

That would make it a building (IMO).

A simple site pole is a structure.

 

[iwire]

Question 1: Does this meet the definition of ?structure,? per NEC article 100?

IMO yes.

Question 2: If the answer to #1 is ?yes,? then do the requirements of NEC 250.32 apply (i.e., is a grounding electrode required)?

IMO yes.

 

[charlie b]

However, if it is underground metal pipe, the pipe may require bonding to the existing GES.

The pipe will probably be metal, and I think it will run underground to the nearby building. Do I correctly infer you are saying it must be bonded to the building's GES, somewhere in or around the building (i.e., not at the skid)?

Just out of curiousity, if you decided it needed a GES at the skid, just what would you bond the rod(s) to?

To the same point on the skid's disconnecting means where I landed the EGC from the incoming branch circuit. At least, that is what I understand 250.32(B) to require.

 

[charlie b]

(To question #2) IMO yes.

Each skid (there are three separate skids) will, in fact, be served by a single branch circuit. Does that change your IMO to a "no"? I ask specifically because another engineer working on the project expressed the opinion that a ground rod is still required. After my attention was invited to the exception (I had missed it earlier), I no longer think a ground rod is needed.

 

[jumper]

I am in agreement with post #2.

 

[iwire]

Each skid (there are three separate skids) will, in fact, be served by a single branch circuit. Does that change your IMO to a "no"?

No it does not.

You had asked ....

do the requirements of NEC 250.32 apply

IMO they apply, but they just happen to include an exception.


If I am not being clear ........ I agree with the others, the exception allows a single branch circuit without an electrode.

 

[petersonra]

The pipe will probably be metal, and I think it will run underground to the nearby building. Do I correctly infer you are saying it must be bonded to the building's GES, somewhere in or around the building (i.e., not at the skid)?

250.50 Grounding Electrode System. All grounding electrodes
as described in 250.52(A)(1) through (A)(6) that are
present at each building or structure served shall be bonded
together to form the grounding electrode system.

250.52 Grounding Electrodes.
(A) Electrodes Permitted for Grounding.
(1) Metal Underground Water Pipe. A metal underground
water pipe in direct contact with the earth for 3.0 m
(10 ft) or more

I think it needs to be bonded to the GES of the building. It is a metal underground water pipe, longer then 10', and present at the building.

 

[charlie b]

Thank you all.

 

[220/221]

Structure. That which is built or constructed.

Another poor choice of words by the folks that bring us the NEC.


Everything but dirt, rocks and trees is built or constructed. A single junction box is a structure.





Around here, a slab would not be considered a structure. Nor would a swimming pool panel mounted on a fence or IMC "rack"

 

[iwire]

Another poor choice of words by the folks that bring us the NEC.

Actually those words were chosen by the building codes, that is were the definition comes from.

Everything but dirt, rocks and trees is built or constructed. A single junction box is a structure.

Yes, and maybe that is exactly the intent even if it bothers us.

Around here, a slab would not be considered a structure. Nor would a swimming pool panel mounted on a fence or IMC "rack"

Well 'around there' you don't seem to follow a lot of the codes.:grin:

 

[Smart $]

Each skid (there are three separate skids) will, in fact, be served by a single branch circuit. ...

Questions:

Are the three skids on the same concrete pad or individual pads?

If all three on the same pad, would that be one structure or three??? I am leaning towards one.

 

[iwire]

If all three on the same pad, would that be one structure or three??? I am leaning towards one.

Seems reasonable.

 

[don_resqcapt19]

Questions:

Are the three skids on the same concrete pad or individual pads?

If all three on the same pad, would that be one structure or three??? I am leaning towards one.

If it is one structure Charlie will have to run a feeder to it as you are not permitted to run multiple branch circuits to feed a single structure. The installation of a feeder with trigger the requirement for a grounding electrode at the structure.

 

[charlie b]

Are the three skids on the same concrete pad or individual pads?

Three separate pads, nowhere near each other.

 

[wawireguy]

If I was engineering it I would probably want ground rods. You said some distance from the building. Makes this equipment more likely to sustain a lightning strike. Talking about pump equipment. Customer does have money to do it right. That's my view.