fitting low gauge wire in 20A breaker

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  #1  
Old 03-22-13, 07:01 AM
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fitting low gauge wire in 20A breaker

My goal is to have power at the barn that is currently housing chickens. My current max power needs are an occasional portable power tool (15A), lighting (5A), and water de-icers (3A). For the ~230' run , it seems #2 Al conductor is recommended for a 20A service.

I was wondering how one would fit a #2 wire into a 20A breaker. Do I need to look at a special order breaker for Siemens panel or I am I looking at going about this the wrong way? The IBC applies to my locality. I will have likely have an electrician do the panel work since that's beyond my level of comfort, but I want to have confidence that the approach is sound.

I am going to call the power company for a cost comparison. I hear that they sometimes offer lower price install on new 100A panels provided you contract for 2yrs of power. Thanks for any guidance on this project.

RD
 
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Old 03-22-13, 07:37 AM
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You could get by with #6 Al. #4 Al would be better. At the box you would pigtail the black to #12 copper. That has to be done with a special connector that isolates the aluminum from the copper such as a Polaris connector. The white and ground should fit the holes in those bars.

Note there is one type of wire nut rated for this but based on the information on the internet it has a high failure rate compared to other methods.

The purple Ideal wire nut only accepts #10 and #12 conductors and will not work with larger sizes.
 

Last edited by pcboss; 03-22-13 at 08:52 AM.
  #3  
Old 03-22-13, 05:12 PM
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If I go with a #6 Al conductor, I believe I would put that in a dielectric connector with #8 copper wire. Will it be possible to find a 20A breaker that will accept #8 copper wire conductor, neutral, and ground?

RD
 
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Old 03-22-13, 05:23 PM
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Dielectric means insulating so a dielectric connector would be an insulating connector. Use the proper connector and use #10 copper to the circuit breaker if #8 is too large. All 20 ampere circuit breakers will accept #10 conductors, most will probably accept a #8.

Neither neutral or grounding conductors will go to a circuit breaker except in the case of GFCI or AFCI circuit breakers which WILL have the neutral connection.

In all cases an equipment grounding conductor (bare or green) will go to an equipment ground bus.
 
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Old 03-22-13, 11:08 PM
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I think you're going to find that you'll end up using #10 wiring.

A good connector for what you are doing is the set screw splice block. They are solid and reliable and I use them all the time. A little anti-oxidant with aluminum wiring and some black tape and you're done.
 
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Old 03-23-13, 09:21 AM
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Thanks for the details. If I go with the set screw splice block, I should be able to afford a heavier gauge Al wire for the 230'. I saw Polaris connectors that could handle low/high AWG and Al/CU, but they are special order at $30/each. I will be using three splices on the barn side of the run and three splices on the house side. Now, I should be able to go with a #2 Al and have the future option of using a higher amp breaker if needs dictate.

Should the splice be inside a separate/dedicated junction box or can it be done at the barn inside the first receptacle box and inside the house service panel?

Also, are there sleeves that go around a set screw splice or will a few tight wraps of tape with anti-ox on inside do the job. I take it the set screw splices are much more affordable since they aren't electrically insulated without wrapping tape around the splice.

RD
 
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Old 03-23-13, 09:34 AM
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three splices on the house side.
Why? you should only need to splice is the hot. The ground and neutral will fit the holes there.

Should the splice be inside a separate/dedicated junction box
In the panel at the house is fine. At the barn you are going to need something larger then a receptacle box. I'd say a 6X6X4 PVC box then next to that in a switch box a 20 amp commercial grade "light" switch (SPST) to serve as your code required disconnect.
 
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Old 03-24-13, 08:54 PM
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Polaris connectors are the preferred method for splicing two wires of different metals of the sizes you have. Or cold taps. If you use the set-screw barrel, make sure the Al and the Cu can't physically touch each other.
 
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Old 03-25-13, 07:46 AM
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ray2047... At the barn you are going to need something larger then a receptacle box. I'd say a 6X6X4 PVC box then next to that in a switch box a 20 amp commercial grade "light" switch (SPST) to serve as your code required disconnect.
For a Multi Wire Branch Circuit, two hots, you need a (DPST).

Although fine, this method is pricey and complicated.

raldem7...I will be using three splices on the barn side of the run...
One splice at the barn method-
For seven bucks you can get an AC Disconnect.
Eaton Cutler-Hammer 60 Amp 120/240-Volt 14,400-Watt Non-Fused Air Conditioning Disconnect-DPU222RP at The Home Depot
Check the label, but the hots and grounds should fit fine in the terminals. There should be enough room for the neutral splice as well.
 
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Old 03-25-13, 07:57 AM
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For a Multi Wire Branch Circuit, two hots, you need a (DPST).
But I didn't think he was running a multiwire circuit. Maybe I missed something. Normally I'd suggest an AC disconnect instead of the 6X6 but I wasn't sure there be room for the #2s.

Fromthe O/P's first post:
For the ~230' run , it seems #2 Al conductor is recommended for a 20A service.
I don't read that as a multiwire circuit.

Raldem7, are you running a multiwire circuit?
 
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Old 03-25-13, 08:11 AM
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Thanks ray2047, I got ahead of myself. But you can still use an AC Disconnect for one hot.

Raldem7, your loads add up to 23 amps. Reduce your aluminum wire size to #4, run two hots, split the load and use the AC Disconnect method.

Normally, with a 20A circuit for the feed, this method does not require ground rods. Agricultural rules may change that. And no panel at the barn.

Speaking of aggie rules, are you allowed to use aluminum wire?
 
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Old 03-25-13, 08:18 AM
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Glenn he's running #2 the last I read. That is why I wasn't sure on room in the AC switch.
 
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Old 03-25-13, 09:19 AM
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The terminals are listed #14-#3. Another brand would get him to #4. #2 is way overkill if you split the loads with a MWBC.

But I'm rethinking this whole approach. If we upsize a 20A circuit for VD, the ground and neutral must also be upsized. That forces three #4 or three #2, and a #4 or #3 insulated or covered copper ground. (Aggie rules, ground must be insulated or covered copper. (NEC '08, 547.5 (F))

If raldem7 uses a double pole 30A to feed the underground, the wires would be: two #4 AL for hots, one #8 AL for neutral and a #10 copper for ground. They would land on the barn on a regular outside breaker panel. (dust proof enclosures needed inside the barn.)

VD would be manageable. And the savings in wire would more than make up for the extra equipment.
 

Last edited by Glennsparky; 03-25-13 at 09:43 AM.
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