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jyalbert 04-14-2011 03:54 PM

Running electrical wire
 
I have a garden shed to which I would like to run electrical power. I have a source of power in my workshop that has a few open breakers in a 125AMP panel. Any running from the current panel to the garden shed would be roughly 60 feet long. I was thinking of running a 10-3 wire with two hots, a common and the ground to split into two circuits once I got to the shed. One would be for a few outlets (internal and outside) and another circuit for the lighting. I would be exiting the workshop for about 20 feet to get to the garden shed where I would put the cable 18 inches underground in a 1 1/2 inch conduit. If this is OK, what sort of breakers would I need at the workshop panel? I was thinking 2 20-amp single pole for each wire (hots-red and black), the common to the neutral bar and of course the ground. Is this enough information to help me ensure I would be NEC compliant? Any safety issues? Is there a better way to do this?

joed 04-14-2011 05:55 PM

Double pole 240 volt breaker should be used not two singles. 20 amp is the maximum if you want to install receptacles or lighting without a panel in the shed.

jyalbert 04-14-2011 07:55 PM

Double pole 240 volt breaker
 
Thanks joed,

Yes, I do not want to install a panel in the garden shed. I was merely going into a box sized large enough for the number of wires and splicing 12-2 wiring of the 10-3 into 2 separate circuits.

I am curious as to how the use of 1 20 amp double pole breaker compares with 2 15 or 20 amp single pole breakers. Is it NEC code? It may be obvious to a professional which I am not. At the other end in the garden shed, I will still be able to split the two hots into 2 120 volt circuits?:huh:

wareagle 04-14-2011 09:43 PM

J
What you are attempting to do is install a multiwire branch circuit. Google that and you can get some information such as wiring dwg, connections etc. It is called multi wire circuit because you are sharing 1 neutral between the 2 hot wires. The breaker must be a double pole breaker to prevent the neutral from carrying the total load of both circuits. It could be overloaded. In your case it probably would not because of the small load you are installing. The other option would be to install 2 ckts and 1 ground conductor and 2 single pole breakers. From what you are describing, a 15 amp would do just fine. Nothing wrong with using 1- 1/2" C but it is larger than necessary. Also you will need to use conductor with insulation rated for underground. Romex will not do. The
receptacles should be GFI type and possible need a weather proof cover. The load you are indicating seems small and you may be able to use #12 cu all the way.

Joe Willie 04-18-2011 07:28 AM

Wareagle,
I'm doing a similar project. Do I need a double pole breaker (20A) at the house sub panel if I am installing a sub panel with 2x20A breakers at the shed? I'm running 10-3 UF.

jbfan 04-18-2011 09:26 AM

Quote:

Originally Posted by Joe Willie (Post 631633)
Wareagle,
I'm doing a similar project. Do I need a double pole breaker (20A) at the house sub panel if I am installing a sub panel with 2x20A breakers at the shed? I'm running 10-3 UF.

Using 10/3 w g allows you to use a 30 amp breaker.

rjniles 04-18-2011 09:32 AM

Quote:

Originally Posted by jbfan (Post 631713)
Using 10/3 w g allows you to use a 30 amp breaker.

If he uses 30 amp breaker, he will have to have a sub in the shed to provide 15 or 20 amp lighting and receptacle circuits.

jbfan 04-18-2011 09:36 AM

Quote:

Originally Posted by Joe Willie (Post 631633)
Wareagle,
I'm doing a similar project. Do I need a double pole breaker (20A) at the house sub panel if I am installing a sub panel with 2x20A breakers at the shed? I'm running 10-3 UF.

Thats what he said.

rjniles 04-18-2011 09:52 AM

Quote:

Originally Posted by jbfan (Post 631725)
Thats what he said.

Sorry Jbfan, I thought you were responding to the first poster, not to Joe Willie

Joe Willie 04-18-2011 10:13 AM

Didn't mean to cut in...I was just reading and wanted to understand the neutral wire issue on the two seperate 20A single pole breakers vs. the single 2x20A double pole breaker. I had been planning on filling two empty slots in the house sub panel with singles. Does a double pole breaker occupy one or two slots?

rjniles 04-18-2011 10:47 AM

A full size 2 pole breaker requires 2 full slots. They do make half size 2 pole breakers that fill the equivalent of 1 slot. They actually bridge across 2 slots occupying 1/2 of each full size slot. To get full utilization of all slots, you need to use half size breakers above and below the 2 pole.

2 pole breaker is required of a MWBC so that both circuits are de-energized off at the same time

Joe Willie 04-18-2011 11:39 AM

Thanks, I learned something else new...makes sense. Let me ask you something else...I just want to confirm. Another DIY poster said when entering input on a voltage drop calculator, you should enter the number of amps from your load calculations, not the breaker size. This makes sense. Is that correct? It really decreases my voltage drop on a long run.

rjniles 04-18-2011 03:12 PM

It depends on what you are trying to do. If your only concern is the existing load and you anticipate no change, then use the calculated load. If you want to ever be able to use the full capacity of the circuit, use the breaker size. #2 is a better option IMO.

Joe Willie 04-19-2011 06:44 AM

Thanks...I know. If I were patient, I would wait till I could afford the 6-3 UF then I would have no problems running 2x20A and 1x15A circuits. I appreciate all the input.

bbddt 04-30-2011 12:52 PM

i thought if you were using a 30 amp you had to use #8 not #10 i have a chart and have to check it to be sure. but doing a project also and if i remember correctly #8 is for a 30amp. someone correct me if thats not right


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