how to determine correct 2 pole breaker size in amps (3rd and final pic)

Question

I need to install a breaker for my model HD-3 arco roto-phase rotary phase converter. it's basically rated "max single motor 3 hp, max total motors running at any one time 12 hp."

it'll be a 2 pole breaker, but what amps should I use? this image shows a nice closeup of the device nomenclature plate...

formatting link

thanks for info guys :-)

toolie 'an electrically dumb guy'

Speedy Jim · Accepted Answer

Will depend on the rating of the motor you're running.Go: out all the sections on the left pane.

gfretwell · Answer

Short answer 8ga copper wire 50a breaker455.6 and 455.7 say 125% of FLA of the total motor load. 12HP worksout to around 38a but it is not specifically listed on 430.150 but 50ashould cover it.

metspitzer · Answer

Or......start with 20 and work your way up.  :)

John Grabowski · Answer

According to the chart #10 wire and a 20 amp breaker is required.

formatting link

You did not mention what you plan to use the phase converter for, but make sure that you size it very carefully for the equipment that you want to connect to it. I've had a few customers over the years get these things and had them sized by the factory and in most cases they needed to be upsized. It not just the motor HP, but also the way the motors are used that affects the performance. Start-up current is one of the biggest problems.

Blattus Slafaly · Answer

The plate says no load amps are 8. So you could double or triple that.If you think it will take 16 amps at full load use a 20 if you think itwill take 24 amps at full load use a 30 amp breaker.

how to determine correct 2 pole breaker size in amps (3rd and final pic)

Join the Discussion

Didn't find your answer?