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Old 05-25-2011, 11:42 AM   #1
GRHunter
 
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Now that I am actually getting into my electric build be prepared for lots of questions in here. I am running 240v 30 amp GFCI for my system. As far as power is concerned I know that for 240v that I need 10 gauge wire, and for the 120v leg I only need 14 gauge wire. Now everything is 10 gauge all the way to my brewing control box. But do the ground wires inside my brewing control box and beyond (to my heating element and March pumps) need to follow those same guidelines?
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Old 05-25-2011, 01:05 PM   #2
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Definitely wait for an electrition (berniebewer is solid) but I believe you can drop down to #12 for the ground.

 
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Old 05-25-2011, 01:23 PM   #3
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Quote:
Originally Posted by RDWHAHB View Post
I believe you can drop down to #12 for the ground.
You can.
Theoretically, you could use any gauge wire for the ground, as it is supposed to not carry any current, and GFCI's need only a few milliAmps ground current to trip, but, in real life, other considerations make that approach impractical, and eventually dangerous.
For what I've seen, it's common to use the next smaller gauge for the ground wire, in relation with the power wires. So, if you're using #10, a #12 ground is ok.
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Old 05-25-2011, 02:30 PM   #4
amb1935
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This calculates sizes according to NEC
http://www.electrician2.com/calculators/t122_122.html

 
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Old 05-25-2011, 04:42 PM   #5
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Quote:
Originally Posted by GRHunter View Post
As far as power is concerned I know that for 240v that I need 10 gauge wire, and for the 120v leg I only need 14 gauge wire.
30A service means you are capable of pulling 30A from either of the hot lines. If you are using one of the two hots and the neutral to form a 120V circuit in your panel, it's still a 30A circuit. 120V/30A.

You will need to use 10 gauge wiring there, too, unless you are running that hot line through a breaker or fuse to limit it to 15A or something.
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Old 05-25-2011, 04:50 PM   #6
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Quote:
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30A service means you are capable of pulling 30A from either of the hot lines. If you are using one of the two hots and the neutral to form a 120V circuit in your panel, it's still a 30A circuit. 120V/30A.

You will need to use 10 gauge wiring there, too, unless you are running that hot line through a breaker or fuse to limit it to 15A or something.
What he said.

 
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Old 05-25-2011, 05:25 PM   #7
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Walker pretty much answered your question, but I will add: The size of the wire required in a circuit is dictated by CURRENT, not voltage. Also the type on insulation of the conductor. The wire is sized such that the current flowing through it will not cause it to heat beyond what the insulation can stand without melting.
Keep it simple and refer to amb1935's link and let that calculate the wire size properly instead of guessing. It seems to fall in line with NFPA specs.
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Old 05-25-2011, 05:28 PM   #8
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right. the power cable I use to bring my supply into my control panel is only 8 gauge wiring, but it's got some fancy schmancy insulation on it that allows it to carry 65A.
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Old 05-25-2011, 06:44 PM   #9
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Thanks everyone. Matching the gauge to the amps makes sense. I kind of thought that would be the answer. But I was hoping that it might be possible to use a thinner wire as it is easier to work with inside the enclosure.
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Old 05-25-2011, 06:48 PM   #10
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Quote:
Originally Posted by GRHunter View Post
Thanks everyone. Matching the gauge to the amps makes sense. I kind of thought that would be the answer. But I was hoping that it might be possible to use a thinner wire as it is easier to work with inside the enclosure.
It is a LOT easier to work with thinner wire. That's part of the reason a lot of people put small panel mount breakers or in-line fuses inside the panels. It not only protects the equipment, but lets you work with smaller/easier wiring.

In my panel, I run noe of my hot lines (capable of 50A), through a 15A breaker about the size of a tube of chapstick. After that breaker, I use much smaller wiring for my 120V stuff.
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