How fast will a 20A breaker trip at 22A?

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  #1  
Old 10-27-13, 01:25 PM
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How fast will a 20A breaker trip at 22A?

I have a separate 20A circuit for the sink waste disposer.

I plan to share this outlet with a mini point of use water heater that draws 12.5A. This heater is to reduce the delay from the tankless heater. It would not turn on very often because it is so small, I may even put it on a timer.

The waste disposer and point of use heater will be on intermittently.

The 1HP InSinkErator Evolution Excel that I would like to buy draws 10.2A. That's 22.7A total, non-continuous.

How long could a garbage disposal be used if the heater happens to be on at the same time, resulting in total 22.7A, before it would trip the circuit? I wonder if I could get away with being slightly over, because of the time factor before the breaker trips when it is only a little bit over. Does anyone think it would trip instantly?

I can also simply use a 3/4HP disposer and stay within the limit. But that's no fun because then there would be no reason to post a question.

In browsing in the past, I think I recall coming across a garbage disposer air switch that turns on power to one outlet while turning the other one off.
 
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Old 10-27-13, 01:30 PM
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Ok I think I found the answer to my own question, the InSinkErator sinktop switch STS-00 which cuts power to the 2nd outlet when the waster disposer is on.

I'll get this switch, but I am still curious on how fast the breaker would trip if I didn't have such a switch.

http://www.insinkerator.com/en-us/Do...h_brochure.pdf
 
  #3  
Old 10-27-13, 01:41 PM
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With a 22amp load applied the breaker may sustain the load for 10-15 minutes before tripping. There is no hard and fast answer as every breaker will be slightly different.
 
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Old 10-27-13, 02:24 PM
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I don't think the point of use water heater will suffice until the hot water reaches the faucet. It may run out way before then. Will you be piping this to your faucet? Have you considered a recirculating pump made specifically for the tankless water heater?
 
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Old 10-27-13, 03:01 PM
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Larry....I think the OP has a tankless water heater and wasn't sure that a circulator pump would work correctly.


Just FYI.... a customer of mine has a temperature controlled circulation pump on his tankless and it works great. He has it in the farthest bathroom.
 
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Old 10-27-13, 03:38 PM
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As far as I know they don't work all that great, as the recirculation action causes the tankless to cycle, defeating the purpose of saving money. I think the point of use will just run out too quickly unless it is at least a gallon or more. Who knows, it may work Thanks, Pete.
 
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Old 10-27-13, 04:23 PM
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It was a close call between the 2.5 gal point of use tank vs. a temp controlled recirculation pump. Eventually I decided on the point of use tank because, on a different thread, people pointed out it would take some extra plumbing parts (some kind of return loop, expansion tank etc) to make it reliable. I didn't want to get that complex.
 
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Old 10-27-13, 04:34 PM
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Good call on the larger tank. It may work just fine in opposition to the recirculation pump on the tankless.
 
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