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Electrical Code - USA Commercial or Residential 1999 / 2002 / 2005 versions - for UNITED STATES

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  #1   IP: 128.221.4.201
Old August 20th, 2004, 08:42 AM
Collins Collins is offline
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Default Size of Wire for Central Air Conditioner 4ton and 3 ton.

What wire should I use?

Thanks Brent
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  #2   IP: 68.193.85.189
Old August 20th, 2004, 11:37 AM
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Tell us the information from the nameplate of the units. They will typically indicate minimum circuit ampacity, in addition to other rinformation.
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  #3   IP: 24.161.81.158
Old August 20th, 2004, 12:55 PM
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Also if you are talking about the condensor alone or both air handler and condensor. They do need separate circuits.
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  #4   IP: 128.221.4.201
Old August 24th, 2004, 05:50 AM
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2500 watts on the 2 1/2 ton and 4500 watts on 4 ton. So I'm thinking that I need a 30amp and a 50 amp circuit. Wire should be 10/3 for 30 amp and 6/3 for the 50 amp. I'm I thinking correctly?
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  #5   IP: 130.76.32.15
Old August 24th, 2004, 12:21 PM
suemarkp suemarkp is offline
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Watts is not the ideal value we need. If that is all you have, we need volts too (I'm assuming 240V). Is there anything that says Mimimum Circuit Ampacity (or MCA), Rated Load Amps (RLA), Full Load Amps (FLA), and/or Maximum Fuse/Breaker? The value we need is MCA, but if that isn't there then we need the motor FLA and the compressor RLA.

From the few AC compressors I've looked at recently, a 2.5 Ton 240V unit would have an MCA of 18 to 23 amps which requires a #10 copper branch circuit (#12 is OK if MCA is less than 20). The breaker installed on this wire would probably be a 25 or 30A depending on what the manufacturer says. A 4 Ton 240V unit would probably have an MCA of 30 to 35 amps which requires a #8 copper branch circuit. The breaker for this would need to be a 40 or 50A breaker again depending on what the manufacturer allows.

You can upsize the wire to the customary sizes for the breaker if you wish -- will be a more efficient installation that way but cost a little more.
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  #6   IP: 114.59.192.242
Old May 31st, 2010, 09:59 AM
centralairunits centralairunits is offline
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I have the similar case,

Thank's a lot for the complete answer particularly on " You can upsize the wire to the customary sizes for the breaker if you wish -- will be a more efficient installation that way but cost a little more."
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Last edited by centralairunits : May 31st, 2010 at 10:07 AM.
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  #7   IP: 24.41.32.240
Old May 31st, 2010, 01:52 PM
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This thread is almost 6 years old.
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