Cyclone amperage question

[David Miller]

Hi all,

Looking for a little advice with an electrical question. I have a homebuilt Pentz design cyclone DC with a 220V 5hp Baldor motor. I have it on a 20 amp circuit. I wanted to make sure I'm not pulling too much current so I hooked up an ammeter to each leg of the circuit. Here are the numbers:

Red leg: 156.2 A max, 10.9 nominal
Black leg: 151.4 A max, 10.6 nominal

The max values are the peak numbers from my ammeter at startup. I'm not too worried about those values since they are momentary. But are the nominal values ok? I guess my question is whether a 20 amp circuit is 20 amps on each leg or both combined? If it's a combined value then I'm overloading the circuit.

These measurements were done with the DC wide open (no resistance) so this should be the highest values I ever get.

Thanks,
Dave

[Jason Beam]

a 240v breaker rated at 20a will have two 120v legs capable of supplying 20a each.

Before anyone gets confused by the 5hp rating and only 10 amps per leg, remember that an impeller does it's most work with no restrictions - any restrictions (the cowling, the duct work, filters, etc) will actually reduce the load on that motor, causing it to draw fewer amps since it isn't working as hard.

[Jay Albrandt]

David,

I have a Pentz cyclone with 14" impeller. When he tested my shop my max reading was 10.3. So I think you are well within the ball park.

Jay

[Art Mann]

The exact same current is present on both legs. It is a continuous current path and the ground does not carry any current. You do not add the readings. Your 10 amp readings are fine for a 20A circuit. Incidentally, if you are getting different numbers on the two legs at the same time, there is something wrong with at least one of the meters.

[David Miller]

Thanks all for the quick replies. I'm glad all is well with the circuit and the DC.

Art, I use one meter to do all the tests, starting and stopping the DC in between. I think the values on the two legs would be even closer if I used two meters at the same time. Plus my meter may have a bit of error associated with it.

Thanks again,
Dave