I’m helping a friend out that runs an animal sanctuary. They have two larger barns and numerous small sheds and they want an outlet in each one. I want to make sure my figures for the correct wire/setup is correct and that I am not overdoing it, or worse, underdoing it. Attached is a diagram of my initial conception.
Basically each outlet, at most, would power a small heat lamp, probably around 2 amps each. Currently the plan is drawn for a 100 Amp service to the first main barn and a branch from that for a 50 Amp service for the second barn. Then each barn will have a circuit or two feeding the smaller sheds for an outlet. I’m kind of feeling that this might be a bit of an overkill and I might do better running a 60 Amp to the first and a 30 Amp to the second?

Am I way off the mark on all this? On track? Thanks in advance for all the help.

 

Welcome to the forums.

There are a lot of variations you can use and of course everyone has their own opinion.
Your basic plan is good. You can never "overkill" an electrical installation. Always plan for expansion.

Your diagram is small and a little tough to read.
Now comes the "here's what I would do".

I would run PVC between the sheds.
If I stayed with UF I'd run 10/3. This would carry two circuits to the sheds.

 

Agree with PJ on the use of conduit or XX-3 cable, not too much additional cost upfront for a lot more flexibility down the line.

Remember that any building that has a panel needs a full earth grounding system. There are also some additional grounding considerations for buildings housing livestock; please let us know if that applies to you. You'll also want to pay attention to any wiring method used inside an animal barn is rugged, corrosion/water/urine resistant and safe for the animals. Usually this means PVC or EMT conduit with appropriate "outdoor" style boxes and covers, but could vary based on the specific application.

Each building will need a "building disconnect" at the first point of entry or on the building exterior, whether it's a panel or a single circuit. This can most cheaply be accomplished with an air conditioner disconnect box.

Not sure if you were planning these, but some interpretations of the codes would also require at least one switched light in any building that has electricity; and some would also require a switched exterior "porch" light. Agriculture areas are usually pretty lax on this and you may be able to meet the requirement by having a central light up on a pole that can illuminate the whole area.

 

Hi guys. Thanks for the quick responses. Sorry for the small picture. I drew it on a sheet of paper and when I did it as a jpg, it comes out small; anyway to fix that?

So the wire runs sound sufficient?
-260’ run of 2/0 aluminum from main panel (3 wires) to 100 Amp sub panel with a #2 aluminum ground through 2” schedule 40 PVC? Anything smaller didn't seem to work for that distance.
-And the 65’ run from that sub panel to the other 50 Amp sub panel would be #4 copper (3 wires) with a #10 copper ground through 1” schedule 40 PVC?
-The runs for the sheds should work as well by using #10…I think at the end of the longest circuit (260’) the voltage drop for 15 Amps was like 7%; acceptable for our applications I believe.

I’ll probably go ahead and run PVC between the sheds….beats having to backfill with sand too...or chopping a line the next time we put in a fence post!

As far as grounding, probably was hard to read on my diagram, but I planned on grounding rods at each sub panel (and removing the bonding screw to boot!) (Still need to figure out what wire/rod requirements for that though.) Where the sub panels are located does house animals. One has roosters who don’t have access to the location of the panel, and the other has chickens running around in it.

I was thinking MC cable in the chicken barns (chickens/roosters are unable to access it) and then EMT in the sheds where the larger, more destructive critters can get into and then using all metal boxes/GFIs in both. Acceptable?

I wasn’t entirely sure whether that was required or not; but would something like this suffice:
GE 60 Amp 240-Volt Non-Fuse Metallic AC Disconnect-TFN60RCP - The Home Depot

I wasn’t really planning on it, but if it’s “recommended” it won’t be too much trouble to throw in a light.

Thanks again for all the help. I really appreciate people like yourselves taking the time to help people like me along.
Matt

 

I would say that 7% voltage drop is way too much for general purpose usage, including such things as a sheep shearer or an electric drill. Shoot for no more than 4% when doing your calculations.

While heaters and lights can withstand 7% voltage drop, your proposed system is not futureproof.

 

Actually thinking about this, couldn't it be run into the shed, to a regular light switch and then to the plug/light switch? Now the switch is the "disconnect"?

 

Yes, but better is a 20amp commercial SPST toggle switch. When you add the cost of switch and box a non fused $6 A/C disconnect which includes a box might be a good choice too.

 

Would something like this work as well? Bell 1-Gang Weatherproof Toggle Switch Cover Combo-TC111S - The Home Depot

I'm going to have to have a junction box on the outside of each shed to continue the circuit anyways, so just throw this on there? $3 bucks, less bulky for goats etc, to knock around...

Thanks again guys!

 

Yes it will work. Best if it is 20 amp. You will also need a weather proof box. Total about the same as an A/C disconnect which is weather proof and includes the box. Here's a $4.88 example. GE 60 Amp 240-Volt Non-Fuse Metallic AC Disconnect-TFN60RCP - The Home Depot PVC weather proof box is $5.79 Bell 1-Gang Weatherproof Box Three 1/2 in. or 3/4 in. Outlets-PSB37550GY - The Home Depot

 

Earth grounding requirement is to use an 8' copper clad rod driven flush to the soil. Use an acorn clamp and #6 bare copper wire to connect the rod to the subpanel ground bus. It's best to drive the rods a few feet from the building where the soil will get wet (not under an eave for example). Some inspectors require a second rod at least 6' from the first one. In that case I run a 15' wire, loop it through the clamp on rod 1 and continue on to rod 2.

If any of these buildings are steel framed you also need to bond this ground wire to a piece of structural steel with an appropriate clamp.

If the building has a concrete floor, you should also bond to a piece of rebar in the slab.

 

Many of the others have more experience with out-buildings and commercial-ish wiring than I do, but I wanted to throw out a different idea for you to at least consider.

Since you're in need of one 20A circuit in each building, what about just running a single home-run 20A circuit to each? It's some extra wire, but a problem in building 3 doesn't cause buildings 1 and 2 to go without power. You can still run all in one 1" or larger conduit, and just "pass-through" the buildings without any connections.

Again, just a thought and might be worth considering.

 

"You'll also want to pay attention to any wiring method used inside an animal barn is rugged, corrosion/water/urine resistant and safe for the animals. Usually this means PVC or EMT conduit with appropriate "outdoor" style boxes and covers, but could vary based on the specific application."



I'm not an electrician, but do have some experience with livestock buildings. The above comment is on target. I would simply add that if you can, use EMT over PVC or another type of conduit.

Where there is livestock, there are mice. Those suckers chew through anything. They are also often attracted to the warmth generated by electrical wires. If they want through the PVC bad enough, they will chew through. Metal is the only thing I have found to stop them.

 

Thanks everybody for all the input I greatly appreciate it. Now I have one more stupid question that I am having trouble wrapping my head around....voltage drop. When calculating this do you anticipate the load at the very end of the run, or the load across the total circuit? For example, let's say we have a 200' run with 3 outlets spaced at 100', 150' and 200' and each individual outlet will have 4 amps. Do I just use the the anticipated load at the last outlet (4 amps), or do I need to calculate the voltage drop using 12 amps (the total load of the circuit)? Or would I calculate the drop at each individual outlet for a combined total drop at the final outlet? Hope this makes sense and thanks again.

 

In the situation you describe, you have to calculate the voltage drop separately for each section of the circuit. A reasonable estimation is to take an average load across the circuit and use that at the furthest point.

 

Okay, I lied, I have another question. Say we wanted to pull 2 separate circuits to 2 separate sets of barns using the same conduit as they're fairly aligned. We'd use separate neutrals and share the ground (both 20 amp circuits). The circuit going to the further set of barns would have to go through 2 junction boxes (at the first 2 barns) and then continue on it's own to the further barns. Is this wise? I don't remember where, but when researching this stuff I thought I read you can't run multiple circuits in a shared conduit to outlying buildings?

 

It is okay to run separate circuits to different buildings in the same conduit. You could even share a neutral between two 20 amp hots if a 2-pole breaker or two handle tied single pole breakers on opposite legs are used.

 

In fact you lessen the effect of voltage drop by using a shared neutral where practical.