What wire for this unit

Hi,

I hope the experts in this group don't feel like I'm asking them to do what I can do myself.

I own this unit:

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which controls the A/C only, not heating.

I need to figure out what wire to run to this unit. I don't want to go by the existing wire b/c the previous owner was not in the habit of doing things right.

Am I reading the document correctly that its 230V and then under 9amps? In that case, should I go simply with a 14/2?

Many thanks in advance,

Aaron

Reply to
Aaron Fude
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Usually the specs sheet tells you what size breaker to use and the breaker determines the wire size. And yours does on page 17.

I have a small 220v AC unit at one of the rentals it is on a 20 amp breaker and wired with number 12 wire. To meet modern codes you need three conductors and a ground so you are looking for 12/3 with ground. I would pull number 12 wire even if I used a 15 amp breaker. Your wire can be over sized but never undersized.

That way if you need to upsize the unit later most likely you will not need new wire, just a new breaker.

Colbyt

Reply to
Colbyt

If you are not using the heating elements, then by the chart on page 17 you need to use a # 14 or larger wire and 15 amp breaker or larger.

Reply to
Ralph Mowery

Page 17 says 14 ga or larger wire, and 15 amp breaker. 230 volt fan.

Reply to
Stormin Mormon

Just to confirm, that 14/2 each wire carrying 120 from opposite phases.

Reply to
Aaron Fude

Hmmm,

12/3 and ground wire? How come?
Reply to
Tony Hwang

Was there ever another choice? You astound me, sometimes. Hey, please call for help on this job. I'm starting to think you're in over your head. At least get someone who's done this kind of thing before.

Reply to
Stormin Mormon
12 to get you 20 amps. 12/3 so that you'll have a white wire, for a neutral. In case some 110 VAC equipment is needed up in the attic. WG, so that there is a dedicated ground.
Reply to
Stormin Mormon

Good advice in my opinion. Just in case the existing or future unit will need 230 volts and also a neutral. And the price of a few feet of 12/3 compared to 12/2 (both with ground of course) or to 14/2 will be so slight as not be very significant. Done that myself several times. The extra wire sometimes coming in useful for extra control or monitoring functions. e.g. hooked up to see if, say, the fans are running???? Another example is our hot water tank; since we had a part coil of

10/3 so we used that and breakered it for 30 amps**. The extra conductor was/is not needed but it avoided buying a separate coil or length of wire for just that. and if ever needed to hook up an indicator lamp to see, for example, how often the lower heating element is cutting in, the wiring is right there back to the panel. ** Just in case, as we once had to, bypass the flip flop thermostat and allow both upper and lower tank heaters to operate at same time, when we had five extra people staying in the house for nearly a month! (And a motor home parked outside at same time for couple of weeks). Lotsa washing up, clothes washing and showers etc. 3000 watts/230 =3D 13 amps. 6000 watts/230 =3D 26 amps.
Reply to
stan

I suppose it would make everyone's brain hurt if I told you it is possible to have a 40a breaker on 14ga wire feeding an HVAC condenser. This all depends on what the minimum circuit ampacity and maximum overcurrent protection is listed on the label.

Reply to
gfretwell

Possible, yes. But safe?

Reply to
Stormin Mormon

Yes.it is safe Motor loads have two components, the locked rotor amps necessary to get it started (the max overcurrent device size) and 125% of the full load run current (minimum circuit ampacity). Overload protection is internal in the compressor. You can also use 310.16 to size the conductors instead of 240.4(D) where the "14ga = 15a" comes from, (14ga is 20a in 310.16) A breaker up to 250% of 125% of full load amps will still protect the conductors in a short circuit condition. I didn't make this shit up, the NFPA did.

Just don't confuse this with any circuit that is not hard wired to a motor. Most of the time 240.4(D) rules (14ga = 15a, 12ga = 20a)

Reply to
gfretwell

Yes it is perfectly safe. With many air conditioners the circuit Over Current Protective Device (OCPD) is only there to provide protection against short circuit or ground fault. The overload protection for both the compressor and the circuit is provided by an overload protective device located at or even in the compressor housing. The overload is designed to allow the compressor to start which with some motor compressor units a breaker sized for the running current or the wire size would not do. So the breaker is sized to the locked rotor current so that the compressor can actually draw enough current to start the load. If the running current increases do to overload then the built in overload at the compressor opens the circuit to protect the supply circuit and the motor from the overheating and insulation failure that would result from a prolonged over current condition.

-- Tom Horne

Reply to
Tom Horne

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