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Help/air compressor tripping 20 amp breaker

B

Bruce

Jan 1, 1970
0
I have a 58' run of 12/3 wire running to the shed that operated some
lights and a small 110v sears 30 gallon air compressor nearly new.
The first time or two of turning it on to build air the breaker blows.
After that it seems to be fine the rest of the day, cycling on/off.
Is my wire run to long and making to much of a current drop???
What can I do to stop this. Anyone? Thanks in advance.
Bruce
please remove SPAMNOT to reply off list if you want
 
S

SQLit

Jan 1, 1970
0
Bruce said:
I have a 58' run of 12/3 wire running to the shed that operated some
lights and a small 110v sears 30 gallon air compressor nearly new.
The first time or two of turning it on to build air the breaker blows.
After that it seems to be fine the rest of the day, cycling on/off.
Is my wire run to long and making to much of a current drop???
What can I do to stop this. Anyone? Thanks in advance.
Bruce
please remove SPAMNOT to reply off list if you want
Not knowing the FLA and LR for the motor try this site for the voltage drop
calculations.

http://www.electrician.com/vd_calculator.html

I have a 15 gallon Sears compressor and it says it draws 15 amps.(FLA)
According to the site
15 amps and 58 feet results in a 3 volt drop or 2.8% well with in
tolerances. Max is 5%. The extra for the lights might be the problem
Have you tried another breaker? Residential breakers do get tired and trip
early after a long time. My home is 30 years old with SQ NQO breakers, I
have replaced the exterior breakers and the pool circuit they just trip to
much
 
D

Darren Fletcher

Jan 1, 1970
0
15Amp FL this might also be a breaker rating issue is it a type C breaker
for motors?
Darren Fletcher
 
B

Bruce

Jan 1, 1970
0
The breaker has on it QD SWD. Does this small motor have a start cap
that can lose stored energy over a short period of time?
I just switched with another breaker and will see.
Still looking for a fix in case the lights dim way down.
Thanks again,
Bruce
 
R

Rusty

Jan 1, 1970
0
The breaker has on it QD SWD. Does this small motor have a start cap
that can lose stored energy over a short period of time?
I just switched with another breaker and will see.
Still looking for a fix in case the lights dim way down.
Thanks again,
Bruce
Start caps are AC devices so they don't store energy between starts.

The problem is quite common starting a small compressor. The inrush
current for an electric motor is about six times the FLA, or 90 odd
amps for a fraction of a second. An ordinary domestic breaker will
not handle this with a cold motor where the duration of the inrush
is longer than when it is warm. You are right on the edge.
Consider getting a breaker rated for a motor start. Fit it in a
separate breaker box if necessary, alongside the main panel.
 
Z

Zzzap

Jan 1, 1970
0
The breaker has on it QD SWD. Does this small motor have a start cap
that can lose stored energy over a short period of time?
I just switched with another breaker and will see.
Still looking for a fix in case the lights dim way down.
Thanks again,
Bruce

"240.83(D)
Circiuit breakers used as switches in 120-volt and 277-volt
fluorescent lighting circuits shall be listed and shall be
marked SWD or HID. [marked HID for high-intensity discharge
lighting]

Use another breaker. It's doubtful that a company would build a
home and leave enough amperage left over on a lighting circuit
to run your compresser.

Keep your compresser separate from the lighting circuit.
Otherwise no matter what you do you'll probably have the same
problem. That might mean running a new circuit for it. It should
be on its own circuit anyway.
 
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