For those setting up a new shop

[Dean Baumgartner]

Something I found out as I was setting up my new shop. I put in multiple circuits for power all around the space and a couple more in the middle of the ceiling. All the 20 amp circuits are single outlet on a breaker. My breaker panel and all the breakers are Square D QO series which is supposed to be the better of their lines. I have had a problem with the compressor and table saw which always ran on a 20 amp circuit with no problem. Well with the new breakers about half the time either the saw or compressor will trip the breaker on starting. Remember these are the only things on their circuit. I checked with one of the electrical engineers at work and instead of the standard 20 amp breakers the Home Depot sells there is a different line called the HM series for high magnetic. This breaker is designed for starting motors that have a high initial in-rush current due to starting a motor. I replaced the breakers feeding the saw and compressor with these and haven't had a problem since. They are more expensive than the standard series about $11 instead of $5 for the standard but for those large 120V motors they sure beat walking over to reset the breaker all the time.

Dean

[Julie Wright]

Dean thanks for passing on the info.
I am going to rewire a few circuits in a few months and was wondering what breakers to use for the table saw and chop saw, both tend to dim the lights. Sometimes the planer trips the breaker. SO you see, I have some rewiring to do.

[harry strasil]

most of those larger motors are 110-220, it would be better to rewire for 220, also on motors that start under load, look for the locked rotor amperage, this is the starting amperage, they take half the amperage to run on the higher voltage

[Dean Baumgartner]

most of those larger motors are 110-220, it would be better to rewire for 220, also on motors that start under load, look for the locked rotor amperage, this is the starting amperage, they take half the amperage to run on the higher voltage

JR,
The saw at least has always run fine on 120V never tripped a breaker even re-sawing some white oak 1x2's. When I finally pry my wallet open enought to get a cabinet saw then I'll put in the 220V. It's just the new breakers that have been specifically designed to trip very quickly that have a hard time with the in-rush. If this wasn't an issue they probably wouldn't have made a separate model breaker just for motors.

Dean