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Old 06-24-2010, 10:54 AM   #16
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240 volt circuit and 120 volt circuit to shed


Your three alternatives are good.

Also:

A 120 volt only feed for more than 20 amps also requires a subpanel if you want to feed receptacles and lights.

I thought that a standard feed of red, black, white, and green, regardless of amperage, was the same thing as a combined 120 and 240 volt circuit.

A 240 volt only feed (actually also a 120 volt feed or 120/240 volt feed) of more than 20 amps can terminate in your shed with a single receptacle intended for the voltage and amperage. In the case of a 30+ amp 120 volt circuit, such a receptacle will not accept ordinary plug in appliances and lights.

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Old 06-24-2010, 12:34 PM   #17
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240 volt circuit and 120 volt circuit to shed


I'm curious why you don't want to do a subpanel here? It's the only thing that gives you maximum flexibility and safety, and doesn't really cost much money.

Workwise it's just a little more labor, but there is such a big payoff.
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Old 06-24-2010, 02:23 PM   #18
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240 volt circuit and 120 volt circuit to shed


My neighbor plans to use this shed for 3-5 years, then sell the property - either taking the shed with him, or selling the shed and contents outright at time of sale.The somewhat temporary nature of this setup points toward least cost and effort. Future "resaleability" of these items and reasonable value is questionable if not impossible Driving 2 ground rods 8' long through Arizona caliche (rock like hard clay) is not something I am eager to do. I see the additional cost:
2 ground rods and clamps
60 amp or higher subpanel
2 additional 60 amp main breakers (in shed and main house service panel)
#6 vs. #8 wire for the shed service
Rental cost for power (maybe pneumatic with air compressor) impact driver for ground rods (and hope you don't hit any utility lines on the way down).
Just looking for the easiest route possible - now leaning toward shed attached to house - though I think that has the least attractive appearance and most hassle to remove without leaving a trace, upon future sale of house.
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Old 06-24-2010, 02:45 PM   #19
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240 volt circuit and 120 volt circuit to shed


Gotcha - those are good reasons.

Here is another possible option: Set up an RV style power supply. Then, you can wire in the shed with a panel BUT have it supplied with a flexible cable plug to the outlet instead of a direct conduit link.

An RV parking spot with power might make for plus for a future purchaser.
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Old 06-24-2010, 03:04 PM   #20
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240 volt circuit and 120 volt circuit to shed


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Originally Posted by fortop View Post
My neighbor wants to wire one 240 volt circuit and one 110 volt circuit to his small shed, about 30 feet from his house. I suggested 1" PVC conduit 18" underground, with 3 each #8 THWN wires (red, white, black - very old style ungrounded 240 volt equipment, so no provision for ground) for the 40 amp rated 240 line, and 3 each #12 THWN (red, white, green) for the 110 volt 20 amp rated outlet. Three questions:
1) Does this sound like the correct conduit size, wire size, and conduit depth?
2) Does the shed need a separate disconnect panel inside the shed, or are the cords from the appliances inside the shed sufficient "disconnect" ?
3) Does this installation require "derating" (i.e. larger wire size required) due to underground location? This is in southern Arizona?
Thanks.
How many amps is your 240 volt line? You should be able to run 2 #12 and 3 #10. But it depends on your amp draw. Or run 3 wires plus a ground and put a sub panel out to the shed, and cut down on your wire runs.
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Old 06-24-2010, 03:26 PM   #21
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240 volt circuit and 120 volt circuit to shed


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Originally Posted by Hazmatt4602 View Post
How many amps is your 240 volt line? You should be able to run 2 #12 and 3 #10. But it depends on your amp draw. Or run 3 wires plus a ground and put a sub panel out to the shed, and cut down on your wire runs.
You really do have to read the other posts first... like the one three replies back from here
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Old 06-24-2010, 03:33 PM   #22
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240 volt circuit and 120 volt circuit to shed


The 240 volt line is 40 amps - manufacturer states minimum #8 wire, 3 wire hookup with no ground provision on this equipment, 50' maximum wire run to equipment allowed. 120 volt line is just for one 20 amp rated circuit, so 3 conductors 12 GA + insulated ground for that.
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Old 06-24-2010, 03:53 PM   #23
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240 volt circuit and 120 volt circuit to shed


The RV power idea sounds intriguing. The largest I have seen is 50 amp, but the style of 240 plug is different, and I am not sure my neighbor will go for a high voltage cable lying on the ground supplying power to his shed. The 240 receptacle is 6-50 style on the equipment.
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Old 06-24-2010, 05:09 PM   #24
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240 volt circuit and 120 volt circuit to shed


Actually, I was thinking that he run the conduit out to next to the shed and up to an outlet on a post. The post would be next to the shed. The shed would have the cable coning out of a box with a weatherproof stress relief fitting and connect to the outlet without sitting on the ground - no long extension cords!

The cord would feed the lugs on the panel.

Like I was saying, think about that shed being an RV, then place the pole where it would make sense for an RV to plug into.
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Old 06-24-2010, 07:09 PM   #25
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240 volt circuit and 120 volt circuit to shed


So, what would be the requirements for the RV pedestal? Does it need to have ground rods, GFCI, etc. When you say the cords would feed the lugs on the panel, do you mean that the cord would go from the RV pedestal to a sub panel in the shed - then to a 240 volt and 120 volt circuit? Seems like you would have to cut the end of a RV power cord and wire it into the sub panel.
I wonder if a GFCI spa box could be mounted on the shed, with 4 conductors to the spa box, 240 volt and 120 volt circuits built in, with main disconnect. Of course, a spa is not a "detached building" per NEC, but the theory seems the same to me. We could put a bird bath inside the shed and say the shed was just a shade cover for the spa.
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Old 06-25-2010, 02:14 AM   #26
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240 volt circuit and 120 volt circuit to shed


Yes, you would use the 50 amp plug wire to power a small breaker panel. the Hot lugs would be connected to the red and black, the neutral bus to the white wire, and the unbonded ground bus to the green wire. Then you place your 40 amp breaker and 20 amp breaker in the panel as usual.

I'm not sure about grounding requirements for RV outlet... though we are kind of cheating this a little, you might want to put the ground rods in anyway. I have pretty hard soil too, and I was able to pound them in with a regular metal post pounder (capped metal tube with handles).
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Old 06-25-2010, 10:56 AM   #27
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240 volt circuit and 120 volt circuit to shed


Since we are thinking "outside the box", any thoughts on a Spa Box - could be 60 amp 240 volt with two built in 120 volt circuits - all protected by GFCI main breaker? From what I read, this just requires 4 conductors from the main service panel, as long as all conductors are insulated. Might be the cheapest/cleanest solution, and might have some resale value in a few years when the owner moves (although I know used equipment is not allowed per NEC rules.)
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Old 06-26-2010, 12:37 PM   #28
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240 volt circuit and 120 volt circuit to shed


Just curious, if there was a 240 volt, 60 amp spa box on the shed (all GFCI), would the ground fault on the spa box trip if it was connected to a 3 wire (no grounding conductor) 240 volt equipment plug. (The plug has no grounding conductor - from the factory that way.)

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