Agricultural

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TeeJay

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I am very new to this, and since you guys know your stuff, and I have this need to know more than what I do, here goes. I have a prefab metal stable that I need to wire. It is 300 feet from the main house. The house is the only building there now. It has a 125 amp service. At one time it had a jacuzzi, so ther is only a 240 volt, 40 amp single phase circuit left on it.The stable will only have 4 lights, 2 receptacles and 3 lights on the outside.Because of the Voltage drop I was planning on running 3 #3 conductors in schedule 80 (buired) to the stables.
My question is ; since this run is 300ft and I will need to install a hand pull , could I treat this as a main service and bond my neutral and equipment grounds together to 2 ground rods and have one rod on both corners of the building?
 
Tom, Yes you can if certain conditions are met.Although if live stock is present,it is recommended to supply the building with an equipment ground conductor.If you have a code book, read up on article 547 and 250.32.If you don't and need the specifics,let us know.
Rick
 
TeeJay said:
My question is ; since this run is 300ft and I will need to install a hand pull , could I treat this as a main service and bond my neutral and equipment grounds together to 2 ground rods and have one rod on both corners of the building?
Click to expand...

You can do it, so long as there will be no other metallic paths between the barn and house. If the owner's planning to run water up there for the horses, make sure s/he uses plastic. ;)

I don't know why you'd need a rod at two different corners of the stable, though. Why not just put 'em near the subpanel?
 
The only reason I had for putting the ground rods at the corners is because there will be two slabs, each one measuring 6ft square and they will be on the inside, I believe you need 20 ft of rebar for a eupher, so i had intended to drive the rods before the pads were poured.
 
TeeJay said:
The only reason I had for putting the ground rods at the corners is because there will be two slabs, each one measuring 6ft square and they will be on the inside, I believe you need 20 ft of rebar for a eupher, so i had intended to drive the rods before the pads were poured.
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Be sure to look at 547.10

Good luck,
 
First off, I don't understand why we're giving DIY advice to someone outside the industry. No offense, T.J., but this is not the site for that, house rules.

Second, a ground rod (or a pair of them) under a 6' square slab is not a Ufer.

Third, I have no idea why such a large conductor is being pulled for such a small connected load.

Fourth, I don't understand why a subpanel is being installed, when a multiwire branch circuit with an EGC would suit this installation just fine.
 
georgestolz said:
First off, I don't understand why we're giving DIY advice to someone outside the industry.
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I didn't read the OP as a DIY question so much as a contractor who doesn't do much ag work. It wasn't until his followup response that I decided it was DIY.

Even so, our "advice" had been to answer a yes/no question, question his ground rod location, and suggest he do some reading in the hymnbook about ag buildings and equipotential grids.

Your suggestion of running a MWBC? Now that sounds like advice. ;) :)
 
Tom, why don't you sub the electrical portion out to an EC? They need to eat too. ;)

Roger
 
I apoligize for the misunderstanding, these grond rods are NOT being buried under concrete, I thought it would be easier to install them first then have the concrete poured around them. Instead of trying to drive them through the concrete when it had set up.
 
Tom, I am glad you are back on your feet and hope your illness is behind you. The way I understand it is that in CA a C-10 license allows a GC to perform all task on buildings of certain classifications, is that correct?

Roger
 
Roger thank you I am back on my feet bue it is slow going, trying to get back what I have lost due to my illness might take a long time. I am 50 years young and I will not let anything or anyone kick me down so I do thank you for your kind words.
 
TeeJay, good to hear you're up and around. :)

Now, what we're getting at is, you're licensed, the work's going to be inspected, all that good stuff?
 
George, that is correct, heck if I was a DIY and am raising the horses that this lady is..... I would have money to burn :) and I would not have to ask anything from anybody I would find the best and let them take the ball and go.But thats not the case. I spent 12 years as an electricians mate in the USN. Now that is a different ball game alltogether. I do not claim to know it all and am not ashamed to ask for help. The most important thing to me is that I install a SAFE system so nobody or livestock gets hurt or fried
 
George the reason for the beefy line coming in to this stable is because she wants to have a riding arena next to this stable with more lighting at a future date. since she informed me of this I figured that I should take this into consideration and not have to pull everything out of this run and upgrade.maybee I'm wrong
 
So, giving the benefit of the doubt...

So, giving the benefit of the doubt...

So, Tom, here are my questions for you:

1. What is the load calculation of the house?

2. What is the connected load at the barn?

3. How big is this future arena planned to be, how many lights around it? Around here, I've seen some substantial poles on private property to light up arenas. If they're going to the trouble of using their arena at night, generally they don't mess around.

Question one will tell us how many amps we have to work with. Question two and three will tell us how many amps we need. I'd bet 35? that the service is too small for the proposed additions to it.
 
Hi George, Okay lets answer those questions;

1. The house has a 125 amp service. Now there used to be a jacuzzi hooked up to this and it was on a double pole 40 amp breaker (the breaker is still in place).
I did not do a load count of the house.

2. The stable is a metal prefab building. It measures 40' long x 36' wide. they want 4 lights inside 2 on the outside and one mounted on a pole outside where they can wash their horses, also 2 receptacles inside. If I use 100 watt lights,
I figure 5.83 amps for the lights, the overall load is going to be about 7.5 amps. Now I figure 80 percent of 40 amps is 32amps so i would have 24.5 amps for the arena.

3 The home owner has no idea how large of an arena she wants, but I did look at the area where she wants this and she would have enough romm for 6 lights.

George, any advice on anything will be gratefully appreaciated.
 
TeeJay said:
1. The house has a 125 amp service. Now there used to be a jacuzzi hooked up to this and it was on a double pole 40 amp breaker (the breaker is still in place).
I did not do a load count of the house.
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You probably should do a load calc on the house. Just because someone installed a 40 amp feeder and removed it before you got there, doesn't necessarily mean that the service is sitting there with 40 extra amps kicking it. So, if your heart's set on offering the barn/arena a 40A 240V feeder, I'd do the calc. :)

2. The stable is a metal prefab building. It measures 40' long x 36' wide. they want 4 lights inside 2 on the outside and one mounted on a pole outside where they can wash their horses, also 2 receptacles inside.
Click to expand...
It's a big structure to only have 6 x 100W lights. Is it mostly for hay storage, or something? (I'm also assuming that in your area, stock tank heaters aren't used in the winter.)

I'm also thinking you're going to be using PAR-38's, which can go up to 120W by a quick search, so we'll go with that. The par holders I just hastily pulled up can accomodate up to 150W lamps, but we'll stick with 120W.

If you were were to use outdoor 4-0 boxes and three-hole coverplates, it's a cinch you'd probably use two parholders per light location. Stop me when my presumptions get to the point that you can no longer walk freely. :D

So for the barn,
4 x 100W = 400W (inside)
4 x 120W = 480W (outside)
2 x 180W = 360W (receptacles)
Total.....= 1240 VA

1240 VA / 120V = 10.3 A

3 The home owner has no idea how large of an arena she wants, but I did look at the area where she wants this and she would have enough romm for 6 lights.
Click to expand...
So 6 pole lights drawing 1.5A apiece would run up around 9 amps.

So, a 20A multiwire branch circuit would more than suffice for all needs. A 15A MWBC would suffice, but who wants an outdoor 15A circuit, right? (Well, actually the MWBC serving my pole light/stock tank/general use receptacles are on a 15A MWBC. But I wouldn't be that cheap for someone else.) :D

Let's see it with 10-3 UF:

VD = 2 x R x I x D
VD = 2 x (1.21/1000) x 10.3 x 300
VD = 7.5V ... 120V - 7.5V = 112.5V
6.2% VD

That looks bad - but once the arena is in, you'd be using 240V, not 120V. Your voltage drop would be around 3%. Let's look at the system max'ed out:

VD = 2 x R x I x D
VD = 2 x (1.21/1000) x 20 x 300
VD = 14.52V ... 240 - 14.5 = 225.5V
6.0% VD.

So I'd run a 10-3 UF on a 20A 2-pole breaker out to the barn. Forget the panel, forget the grounding electrodes (throw them in if you'd like).

That's my opinion.
 
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