15 Amp to 20 Amp?


Old 01-14-08, 12:40 PM
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Question 15 Amp to 20 Amp?

I had an electrician wire 2 receptacles in my garage for 2 portable heat/cool air conditioners. They are on seperate 15 amp breakers in my sub-panel. I have since changed my mind about using these as my source of heat and will be installing a couple of 1500W wall heaters which will only require 120V's. I've done some research on the particular models that I will be buying and it appears that they will require 20Amp breakers and 12/2 wire.

My questions are........
1)I have no idea what kind of wire is going to the 15Amp receptacles right now but I'm pretty sure that it is not #12. My guess is #14. How can I determine what it is?

2A)Will the wall heaters need to be on seperate breakers or can I possibly piggyback 2 heaters on 1 20Amp breaker safely?


2B) Since there is nothing else on the receptacles for the 15Amp breaker could I wire 2 lines, 1 hard line to the heater(winter) and 1 outlet for a small window air conditioner (summer)?

Thanks in advance!
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Old 01-14-08, 12:51 PM
Join Date: Sep 2003
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1. Look at the cable/wire.

2a. A 20 amp circuit can supply 20 * 120 = 2400 watts. Limiting this to 80 percent yields 1920 watts. Since two times 1500 is more than 1920, you need two circuits. But you knew this, since you determined (somehow) that a 15 amp circuit was not enough.

2b. In theory you could do this, but not in actuality. They would need to be 20 amp circuits anyway. I suggest that you leave the 15 amp circuits in place and add two 120 volt circuits for heat. Better yet, make the heating circuit a single 240 volt circuit and use 240 volt heaters.

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