Horse Arena

[jmellc]

I am looking at a job for a horse arena, about 150 by 250. 11 columns down to concrete pedestals on each long side. Columns join to bar joists going all the way across a sloping ceiling.

If I drive a ground rod next to each pedestal and ground from it to the column, should that give a good equipotential ground/bond? Or do I have to form a ring with them all? I will also ground panel to a column and to 2 ground rods.

 

[tom baker]

Are you considering this building under the scope of Article 547?

 

[jmellc]

Are you considering this building under the scope of Article 547?

I'm sitting down with the NEC tonight to see what I can decipher. One of my weaknesses with code is putting together the info on things I haven't done before or haven't done in recent years.

 

[Ponchik]

Why do you need a ground rod at each column?

 

[Volta]

The NEC doesn't dictate precisely how you must do it, but your idea of a bare wire, maybe a #8 is probably much more effective than rods if the floor is concrete. Mesh is even better, but if not spec'd you might want to call that cost out separately.

You may have many water lines, maybe underground, but probably non-metallic. But anything a horse can touch that can become energized is best bonded.

Are parts of the floor concrete?

 

[kwired]

I'm sitting down with the NEC tonight to see what I can decipher. One of my weaknesses with code is putting together the info on things I haven't done before or haven't done in recent years.

Read 547.1 first and decide if you need to go any further.

547.1 Scope.
The provisions of this article shall apply to the following agricultural buildings or that part of a building or adjacent areas of similar or like nature as specified in 547.1(A) or (B).
(A) Excessive Dust and Dust with Water. Agricultural buildings where excessive dust and dust with water may accumulate, including all areas of poultry, livestock, and fish confinement systems, where litter dust or feed dust, including mineral feed particles, may accumulate.
(B) Corrosive Atmosphere. Agricultural buildings where a corrosive atmosphere exists. Such buildings include areas where the following conditions exist:
(1) Poultry and animal excrement may cause corrosive vapors.
(2) Corrosive particles may combine with water.
(3) The area is damp and wet by reason of periodic washing for cleaning and sanitizing with water and cleansing agents.
(4) Similar conditions exist.

I wouldn't consider a horse "arena" as a 547 location in most cases. The animals typically are not housed in the arena and are there temporarily for performances. Kind of no different than bringing a rodeo to an arena or auditorium or similar venue as a one time event or a parade route where horses are in the parade. Now areas next to the arena where horses may be housed on a permanent or at least more routing basis could be 547 applications. JMO.

 

[ActionDave]

I wouldn't consider a horse "arena" as a 547 location in most cases. The animals typically are not housed in the arena and are there temporarily for performances. Kind of no different than bringing a rodeo to an arena or auditorium or similar venue as a one time event or a parade route where horses are in the parade. Now areas next to the arena where horses may be housed on a permanent or at least more routing basis could be 547 applications. JMO.

I would agree. I have precious little experience in this area. I base my opinion on conversations with my boss and the inspector about a mom and pop goat milking shed.

The final upshot was 547 did not encompass every area involving animals. It was decided that it did involve us; we had to chip out some concrete and bond to the mesh in the slab. YMMV.

 

[Fulthrotl]

I am looking at a job for a horse arena, about 150 by 250. 11 columns down to concrete pedestals on each long side. Columns join to bar joists going all the way across a sloping ceiling.

If I drive a ground rod next to each pedestal and ground from it to the column, should that give a good equipotential ground/bond? Or do I have to form a ring with them all? I will also ground panel to a column and to 2 ground rods.

my electrical engineer mentioned to me once about grounding in dairy,
and it's importance, and said horse barns should be considered in the
same light. take that for what it's worth.

just for grins, three spools of #6 bare copper would make a loop around
the whole thing, tying to the two ground rods, and the panel. i've got #6
cadweld blocks, so i'd just cadweld the whole thing, and be done with it.
that's what my EE would specify for a dairy, or horse barn.

the copper is $650, current pricing. cadweld shots are about $4 each in
that size, iirc.

i don't see any merit in the individual ground rods. it's not a substation. ;-)

so, $900 would cover material for grounding.

 

[jmellc]

Why do you need a ground rod at each column?

I thought that would approximate using a grid. Columns are about 25 feet apart, along each long side. Each column grounded to earth should even out potential across the area. Should help too, if any section of metal roofing ever came loose, give continuous path to ground nearby in both directions.

 

[jmellc]

The NEC doesn't dictate precisely how you must do it, but your idea of a bare wire, maybe a #8 is probably much more effective than rods if the floor is concrete. Mesh is even better, but if not spec'd you might want to call that cost out separately.

You may have many water lines, maybe underground, but probably non-metallic. But anything a horse can touch that can become energized is best bonded.

Are parts of the floor concrete?

Dirt floor all the way. The only concrete is in the pedestals, about 4 x 4. I wish they had called before pouring pedestals, I could have gotten a ground wire to the rebar in them.

I don't think any water lines are there. I saw no faucets of any type. Only power is lights, receps every other column and lights/receps for a speaker's box.

 

[kwired]

Dirt floor all the way. The only concrete is in the pedestals, about 4 x 4. I wish they had called before pouring pedestals, I could have gotten a ground wire to the rebar in them.

I don't think any water lines are there. I saw no faucets of any type. Only power is lights, receps every other column and lights/receps for a speaker's box.

read 547.10(A)

If there is no concrete floor, no equipotential plane is necessary.

The primary reason a equipotential plane is necessary is because of the distance between legs of animals like horses or cattle. If there is voltage gradients in the floor they have a longer "base" as well as twice as many points of contact as people so they can stand there and span over a larger voltage gradient much easier than a person can. This has been known to cause production problems in dairy cows, and they are much more likely to have more electric powered equipment in their vicinity than many other animals usually have. Sometimes enough current flows that cows feel it and they will just stay away from certain areas because of that. Not good if the area happens to be a zone around a water tank that has a fault in it, they will just stay away from the tank and will suffer from lack of water because they feel the current before they even get close enough to think about taking a drink.

 

[jmellc]

read 547.10(A)

If there is no concrete floor, no equipotential plane is necessary.

The primary reason a equipotential plane is necessary is because of the distance between legs of animals like horses or cattle. If there is voltage gradients in the floor they have a longer "base" as well as twice as many points of contact as people so they can stand there and span over a larger voltage gradient much easier than a person can. This has been known to cause production problems in dairy cows, and they are much more likely to have more electric powered equipment in their vicinity than many other animals usually have. Sometimes enough current flows that cows feel it and they will just stay away from certain areas because of that. Not good if the area happens to be a zone around a water tank that has a fault in it, they will just stay away from the tank and will suffer from lack of water because they feel the current before they even get close enough to think about taking a drink.

What has never been clear to me is this. It sounds like there is current in the ground or floor they walk on. Where is that current coming from? If all eqpmt is in good condition, wiring OK, where are they feeling the charge from?

 

[kwired]

What has never been clear to me is this. It sounds like there is current in the ground or floor they walk on. Where is that current coming from? If all eqpmt is in good condition, wiring OK, where are they feeling the charge from?

Remember that all grounded systems that interconnect in any way have a low impedance between each other through the bonding between them. Voltage drop on the multiple grounded neutral of the POCO primary distribution is a real common source of "stray voltages"

By creating an equipotential plane you are not eliminating these currents, you are just equalizing potential between points that can be touched at the same time. We do the same thing with bonding everything in and around swimming pools. While you are in the pool you may be sitting at a voltage above true ground, but everything within your reach is at same potential so you have no voltage differences which means no current flow through your body either.

 

[ptonsparky]

Think of the bird on a POCO wire. They are at the same potential as the wire so no shock occurs.