# Simple Electrical Circuit to Shed -- 150 feet away

I want a very simple line to a shed, about 150 feet away. I assume that I want about a 20 amp circuit, max. I want it for power drills, a grinder, etc. Maybe even a 100 watt light, but not much more.
Am I correct in believing that I can use 12/2 UF wire for this purpose ?
Is there a need to go to 10/2 for this length of wire ?
--James--
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I
grinder,
?
http://www.electrician.com/vd_calculator.html
Adding into the form a 10 amp load, I come up with 5.9 volt drop or 4.9% As long as you never go over 10 amps your good to go. Personally I would go for the number 10, just incase you decide to expand some day.
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James Nipper wrote:

Yes.
Not really a *need*, but it would be a very good idea, in case you ever want to get a table saw or air compressor. Even with high copper prices, the wire is a lot cheaper than the trench to bury it.
Bob
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Thanks for these good comments !! Number 10/2 will be what I will order.
Am I right on making it a 20 amp circuit ??? I think so.........
--James--
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Maybe, maybe not.
What is in store for the future? Telephone? Cable TV? Just bite the bullet and install a duct bak consisting of 6- 4" PVC coated galvanized pipes encased in a 2' x 3' concrete (dyed red) form.
3 conduits are future spares, and in the remaining 3 install in each a set of 4 x 500KcMil rubber insulated. Rack these feeders and arc-proof tape them where exposed in manholes or handholes.
Use current-limiting crabs and hydraulic compression connections only, spliced within 3M waterproof splice kits.
At least, that's how they feed a shed for garden tools in Central park, New York!
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HA HA Budys Here posted for all of us....

What are current limiting crabs?

--
Tekkie

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Crabs are sort of like, fuses a utility uses on underground feeders. Parallel feeders serving multiple loads are connected through a "crab" which has very little in the way of overload protection, but will blow for a short circuit.
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Check this site for the size wire needed:
http://www.elec-toolbox.com/calculators/voltdrop.htm
According to this calculator you need #8 wire for 15A and number #10 wire would provide only 9A for a 3 percent volatage drop. You need #6 wire to get 20A with a 3 percent voltage drop.
Don't know what your local code says, but if you are going to run motors you need to consider the voltage drop. So, using a 20A circuit breaker, if allowed, is a gross misrepresentation, since you would never get satisfactory service with a 20A draw with #10 wire.
James Nipper wrote:

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George E. Cawthon wrote:

#10 wire and a 15A draw would give a 3.7% drop. Not many tools draw over about 10 amps. At 20A, the voltage drop is 5%, which is still acceptable (barely). For what the original poster described, #10 should be fine.
Bob
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zxcvbob wrote:

What are you using that shows the percent voltage drop? book, online, etc.? I would not have expected only a 3.7% drop with 15A, given the calculator result for 3 percent drop on #10 wire (9A draw). You are right for what the op wants to use. But a 15A breaker would be more reasonable for that length and size wire.
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George E. Cawthon wrote:

I was calculating them by hand at first, then I found this web calculator that actually shows you what it's calculating:
http://www.stealth316.com/2-wire-resistance.htm
It's not as simple to use as that one on elec-toolbox.com, but it has the resistances for different gauge wires, and it calculates all of them and lets you decide what to use.
Bob
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If you can swing the cost, I'd go with 10-3. This will allow two separate circuits, and any load on one circuit will reduce the voltage drop on the other. Consider lights and any fixed loads on one circuit, the receptacle for tools on the the other. Protect this with a double pole 15A or 20A breaker.
--
Mark
Kent, WA
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James Nipper wrote:

Given the distance I would suggest going with the 10 AWG wire. This will avoid beeting your electric tools to death with low voltage during starting. -- Tom Horne
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as long as you are doing it why not just run something capable of having 220.... dont build it to your minimum spec but the maximum possible.
lots easier to change things now than later.
randy

I
grinder,
?
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That is what I thought too. Pretty cheap to run 3-#6 wires and a small breaker panel. Then he would have power for most anything. Greg
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as long as you got the trench dug, run a phone wire too. consider running some coax for cable tv too. cable in the shop is nice <g>
randy
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I
grinder,
?
12 gauge wire is sufficient for the load(s) that you describe. The NEC (recommended) total volt drop for feeders and branch circuits together is 5%. Since you aren't using a feeder, the total volt drop for the branch circuit can be 5%. Drawing 10 amps on a #12 wire 150' yields a 5.9 volt drop with 114.1 volts at the load (4.9%).

If you anticipate more load than what you described, a #10 wire would be preferred. You may want to consider renting a direct burial cable machine.

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