Window Unit AC: which receptacle?

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Old 07-07-05, 09:26 PM
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Window Unit AC: which receptacle?

I am currently rewiring my second floor. I've pulled 12/2 and have 20A breakers. Th 2nd floor is just one big room. I have 4 computers running and need to supplement the cool. The AC's I've looked at are 15A 115v or 20A 230. I've not set the receptacle for the AC yet and there will be other devices on this circuit. What should I do if I buy a 15A 115v rated AC?
 
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Old 07-07-05, 09:55 PM
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What you should do is to buy the 240 volt air conditioner, and then put it on it's own dedicated circuit.

If you insist on buying the 120 volt air conditioner you should put it on it;s own dedicated circuit.

Let me also suggest that you run at least two circuits for the computers. Perhaps more if you have any laser printers or other high energy draw peripherals.
 
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Old 07-07-05, 10:04 PM
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Well, I've already pulled the 12 guage wire and the room is only about 450 sqaure feet. What I need to know most is; Can I use a regular 15A receptacle with a 20A breaker and 12/2 run or should I use a 20A receptacle (or are they just for 230v). Also, do they make receptacle with breakers in them like the receptacles with 1 plug-in and 1 fuse. I want to make sure I don't overload the receptacle or AC power cord?
 
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Old 07-07-05, 10:14 PM
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I think you are in over your head.

In the US, you are allowed to put 15 amp receptacles on 20 amp circuits or 20 amp receptacles on 20 amp circuits.

If you have already run 12-2 wire and only ran one circuit for this new room, then you don;t have a choice to make. You can only use a 120 volt air conditioner. Whether you use 15 amp receptacles or 20 amp receptacles is up to you.

However, let me reiterate. If you put this air conditioner on the same circuit as your computer equipment, you will trip the breaker. In fact, even if you don't have the air conditioner on you will still trip the breaker if you try to run four computers on one circuit.

You do not have to worry about overloading the power cord or the receptacle. The breaker will trip long before that happens. And it will trip, unless you split that circuit up.
 
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Old 07-07-05, 10:38 PM
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I'm already running 4 computers on the existing 12 guage that is on this 2nd floor. The 12 guage that exists is old and has no ground, just a nuetral. I've run two 12/2 lines to this room. I want to ground my equipment though and put my New Mac G5 on a UPS which requires a ground. You may be right about being in over my head, but I'm trying to resolve that. The reason I stated 20A/230v in the earlier thread is that is what I read on the box of an 8000 btu AC in addition to 15A/115v. I replaced an electric attic fan last week and it has helped the central unit work less and I'm not looking to cool the upstairs with a window unit alone. I've got 2 registers and one return.

I agree a 220 would be ideal, but I'm just wanting to keep my dual processor computer at a constant temp and also be grounded. Thus the two 12 guages. I appreciate your input and welcome more. I think explaining my current conditions better helps your view (maybe not). But I am glad to know that you can use the 15A or 20A receptacle on a 20 amp circuit.
 
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Old 07-08-05, 05:36 AM
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If you plan to put this air conditioner on a dedicated circuit then you could go with either a 240 volt unit or a 110 volt unit. As long as the current requirements do not exceed 20 amps you can use the 12 gauge wire. The difference would be at the panel in the size breaker you use and where you connect the wires.

Regarding the computers, four is pushing it for one circuit, and I woud not push it. If you are managing then they are either low power computers, low power monitors and/or few or low power peripherals.
 
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Old 07-08-05, 06:01 AM
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An 8000btu A/C will not be a 20a/230v circuit. It will be 120v and about 7.5a if it is new. This is not huge for those circuits if you are careful what to share the circuit with.
I get the idea this is all done and you are looking for a solution after the fact. If so deal with juggling the load and have the a/c on with other things.



the room is only about 450 sqaure feet.
This is no small room. I do agree that a dedicated line to a larger a/c would be best, but since you do have central and this is just supplemental you should be OK.
 
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Old 07-08-05, 08:01 AM
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Since you've already pulled a 12/2 to the room, you obviously have the skills necessary to pull another one. Maybe not required, but I strongly suggest it.
 
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Old 07-08-05, 12:03 PM
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S-T; you state---- "I've run two 12/2 ( cables) to this room"----

One of the two cables should be a seperate-circuit for the window A-C unit ONLY and can be connected for either 120 volts or 22O volts. You can protect the 12/2 cable , depending on the amp-rating of the receptacle, with either a 15 amp or 20 amp C-B., single or double-pole.The important consideration is that the A-C receptacle conform to the pattern of the cord-plug of the A-C unit you select.

As to the other 12/2 cable, the power-capacity of the B-C is 20 X 120 = 2400 watts. You may have to assess the total load, in watts, of the computor network to determine if one 20 amp circuit is adequate.

Good Luck & Enjoy the Experience!!!!!!!!!!
 
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