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Old 08-27-2012, 07:02 PM   #1
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10/2 cable


Just curious, what do you use 10/2 cable for? I know 10/3 is for dryer and water heaters because they take 240V. But i've never seen 10/2 used anywhere

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Old 08-27-2012, 07:09 PM   #2
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10/2 cable


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Just curious, what do you use 10/2 cable for? I know 10/3 is for dryer and water heaters because they take 240V. But i've never seen 10/2 used anywhere
Any load that requires it...

Water heaters are 240v by the way, and would only use 10-2.... dryers are 240/120 and require 10-3...

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Old 08-27-2012, 07:41 PM   #3
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10/2 cable


I thought HWH needs 10/3
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Old 08-27-2012, 07:43 PM   #4
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I thought HWH needs 10/3
Why did you think that? Where would the neutral come into play?

The only reason dryers use 10-3 is because if they used a 240 volt motor, they could not be used with a 208v service, so it's much more versatile to sell them with a 120v motor....

Water heaters use strictly 240v heating elements.

Last edited by stickboy1375; 08-27-2012 at 07:47 PM.
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Old 08-27-2012, 07:47 PM   #5
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10/2 cable


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Originally Posted by amakarevic View Post
Just curious, what do you use 10/2 cable for? I know 10/3 is for dryer and water heaters because they take 240V. But i've never seen 10/2 used anywhere
240V AC Compressor with face plate requirement for a circuit max amps from between 20.01 and 30.00 that must be proected with a 30A breaker.

I have this set up. AC requires 20.5 amps. Neutral is not used - white wire is reidentified as a hot
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Old 08-27-2012, 07:51 PM   #6
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10/2 cable


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240V AC Compressor with face plate requirement for a circuit max amps from between 20.01 and 30.00 that must be proected with a 30A breaker.

I have this set up. AC requires 20.5 amps. Neutral is not used - white wire is reidentified as a hot
Number 12 awg is good for 25 Amps in your scenario. and you're probably reading the nameplate incorrectly.
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Old 08-27-2012, 08:10 PM   #7
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10/2 cable


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Why did you think that? Where would the neutral come into play?
I never did understand where the neutral (white) does come into play. But 10/2 still has a neutral (white) just not an extra hot (red). Or do you mean red by neutral?
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Old 08-27-2012, 08:13 PM   #8
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[QUOTE=amakarevic;997882]
Quote:
Originally Posted by stickboy1375
Why did you think that? Where would the neutral come into play?./QUOTE]
I never did understand where the neutral (white) does come into play. But 10/2 still has a neutral (white) just not an extra hot (red). Or do you mean red by neutral?
Eh, neutral is always white, white isn't always neutral... remember that.

with that said, a 10-2 could be used as 120v, or 240v...

10-3 is 120/240v....
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Old 08-27-2012, 08:15 PM   #9
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10/2 cable


Typically for 240v we'd use it for a water heater or A/C condensor. Also the odd large power tool. Not much else.
For 120V it's SOP for a 30A/125V travel trailer circuit.

Listen to Stick, he's spot on (as usual).
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Old 08-27-2012, 08:33 PM   #10
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10/2 cable


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Originally Posted by stickboy1375 View Post
you're probably reading the nameplate incorrectly.
did I read it wrong? (not sarcastic, first ac compressor supply wiring ive ever done)
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Old 08-27-2012, 08:44 PM   #11
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did I read it wrong? (not sarcastic, first ac compressor supply wiring ive ever done)
I was hoping you were going to post a pic.

Okay, so this is how you size a unit... you take that MIN circuit ampacity, which happens to be 20.5 amps, now, we look under table 310.16, #12 is good for 25 amps because we are not restricted to 240.4(D) requirements... #14 AWG is good for 20 amps by the way, but your unit is just over this.

Next, the maximum circuit breaker is 30 amps, so that is perfectly fine on # 12 AWG, because the motor contains the over current protection, thus... the circuit breaker is only providing ground fault and short circuit protection.
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Old 08-27-2012, 08:50 PM   #12
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10/2 cable


Wow, Thanks Stick! You are the Code Guru.

I dont regret installing the larger cable.

Having said that, I wish I had spent 2 years on this forum prior to doing any of my project.
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Old 08-27-2012, 08:53 PM   #13
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10/2 cable


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Wow, Thanks Stick! You are the Code Guru.

I dont regret installing the larger cable.

Having said that, I wish I had spent 2 years on this forum prior to doing any of my project.
There is nothing wrong at all with the larger wire run, I wouldn't fuss over it, but, when you are bidding a job, or if you think you have to run the wire that meets the maximum breaker size, that's different.
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Old 08-27-2012, 09:43 PM   #14
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There is nothing wrong at all with the larger wire run, I wouldn't fuss over it, but, when you are bidding a job, or if you think you have to run the wire that meets the maximum breaker size, that's different.
personally i like to size my wire for the breaker size even though it's not required just because i'm funny like that. That would only apply for my own stuff though. Your absolutely right, when doing a job for someone anywhere you can save them money and stay legal is a plus. On a small job $20 or $30 can make a big difference in a bid when your only talking $400 for the whole job.
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Old 08-27-2012, 09:47 PM   #15
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personally i like to size my wire for the breaker size even though it's not required just because i'm funny like that. That would only apply for my own stuff though. Your absolutely right, when doing a job for someone anywhere you can save them money and stay legal is a plus. On a small job $20 or $30 can make a big difference in a bid when your only talking $400 for the whole job.
I find it hard justifying it, because I wouldn't do it for any other application, so I dont know why I would do it for an AC unit. The only time I apply voltage drop is when I absolutely know I have to.

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