F.A.UNIT BREAKER TRIPS ..!!

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dleon

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I did a trouble shoot in a house the f.a.u. breaker trip. I wanted to know why it trip so I started doing my search ,came up to be that f.a.u draws 16.5 when it kicks on . now my question is can I size this to a 20 amp breaker and keep the 14 awg wire ? is only 16.5 when it first kicks on then is at 9.6 amps ..following article 440.22 ac. sizing it to 175%
 
dleon said:
I did a trouble shoot in a house the f.a.u. breaker trip. I wanted to know why it trip so I started doing my search ,came up to be that f.a.u draws 16.5 when it kicks on . now my question is can I size this to a 20 amp breaker and keep the 14 awg wire ? is only 16.5 when it first kicks on then is at 9.6 amps ..following article 440.22 ac. sizing it to 175%
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What is the specification for the motor? A starting surge of 16.5A is not going to trip a typical 15A breaker. (A sustained 16.5A may not even trip a 15A breaker over the time the FAU (?) is on.) How long does this level of current last?
Possibly the motor is underrated for the application?

Meanwhile, if the motor has its own integral overload protection, you can indeed size the wire by the nameplate Minimum Circuit Amps (MCA= 1.25 * FLA) and still put in a larger breaker up to the maximum OCPD specified for the motor. (This assumes that the single motor load is the only significant load on that branch circuit.)

PS: A photo-finish with Curt. :)
 
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dleon said:
I did a trouble shoot in a house the f.a.u. breaker trip. I wanted to know why it trip so I started doing my search ,came up to be that f.a.u draws 16.5 when it kicks on . now my question is can I size this to a 20 amp breaker and keep the 14 awg wire ? is only 16.5 when it first kicks on then is at 9.6 amps ..following article 440.22 ac. sizing it to 175%
Click to expand...

You should be sizing the wire and overcurrent device according to the name plate not to what your meter says. The manufacture is required to provide the minimum circuit ampacity and maximum overcurrent protection on the nameplate. the manufacture has already done the calculations so you should not be adding anything to these values.
 
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