Circuit breaker question (240 vs. 120)

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  #1  
Old 12-29-05, 03:14 PM
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Circuit breaker question (240 vs. 120)

Background:
I recently had an old air compressor die on me. It was a 240v unit on a dedicated circuit. The new unit I replaced it with (although much better) is only 120v. I plugged it into an existing outlet but the load it puts on it trips the breaker occasionally.
My question:
Can I keep my existing circuit breaker (2 pole) on the dedicated circuit? I planned on replacing the 240v outlet with a 120v outlet and moving the 2nd hot lead (white) to the ground terminal. Is there any good reason I can't do this?
Thanks.
 
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Old 12-29-05, 03:26 PM
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Please check that you are using both the proper receptacle configuration and voltage rating. Your 120 V compressor cord should not fit into the 240 V receptacle. This is to prevent damage by applying the improper voltage.

Your need to check the circuit size to see if it is adequate for the new compressor. What was the old compressors ampacity? What does the new compressor call for?
 
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Old 12-29-05, 04:29 PM
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circuit breaker question

Before you go pulling receptacles, etc. check to see if the motor on the compressor will operate at 240 volts. It is usually a matter of installing a jumper in the swing away plate on the back of the motor (if it has one). Look on the motor to see if it is dual voltage. It will save you a lot of time and you will get alot faster spool up speeds with the higher voltage, as I am sure you know having had one already.

Larry
 
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Old 12-29-05, 05:26 PM
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pcboss: I know all of those issues are covered. I only questioned "converting" a 2 pole breaker configured for 240v to only using it as a 120v breaker. But thanks for confirming what I was already pretty sure about.

chandler: I thought about that, but I don't see that it is worthwhile to keep the old configuration when new equipment is downsizing. (Meaning that any future needs will probably be 120v as well.)

I really only want to know about using a 2 pole circuit breaker to only drive a 120v outlet.
 
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Old 12-29-05, 05:30 PM
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The 2 pole breaker will not be a problem since your only using half of it by landing the white {if necessary} on the neutral bar in the panel.You also will not need a fillerplate in the panel like you would if you swithced to a 1 pole
 
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Old 12-29-05, 05:35 PM
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Yes, you can use half of a double-pole breaker as a single-pole breaker. But it's not safe unless the amp rating is correct.
 
  #7  
Old 12-29-05, 06:00 PM
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Okay...

Originally Posted by John Nelson
Yes, you can use half of a double-pole breaker as a single-pole breaker. But it's not safe unless the amp rating is correct.
If I buy a 20 amp breaker 2 pole breaker and only use 1 pole of it, what will the amp amount to trip it?

I had a 20a 240v 2 pole breaker. I've only wired a single wire to it and am assuming that the circuit is still at 20a. If I need to add another "circuit" I intend to replace the 2 pole breaker with two 1 pole breakers. I require 20a rating on the 2 pole, using it as 120v. Will that work?
 
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Old 12-29-05, 07:11 PM
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If I buy a 20 amp breaker 2 pole breaker and only use 1 pole of it, what will the amp amount to trip it?
20 amps, just like all 20-amp breakers.

If I need to add another "circuit" I intend to replace the 2 pole breaker with two 1 pole breakers. I require 20a rating on the 2 pole, using it as 120v. Will that work?
Yes. You could leave the double-pole breaker even when you add another circuit if you want. The only downside would be that if either circuit trips they both do. But in a well-designed electrical system, breakers should (almost) never trip.
 
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