Felder Hammer A3-41 power requirements

[MyKidsDad]

Does anyone here happen to have, or happen to be familiar with, a Felder Hammer A3-41? I've been emailing a Felder rep and specifically asked him if a 230V 20A circuit would work to power the machine. His reply was less than a straight-forward answer to me. 

Here's my question (black) and his answer (red)...
I’d like to confirm that a 240V 20A circuit is adequate to power the A3-41? That's perfect, the machine requires 230V 30 amp but you can go down our up either way. 

I don't know how it's ok to go down if the machine requires 30A as he says. So, can anyone tell me if I'm fine with a 20A circuit, or if I need to try and upgrade to a 30A circuit if I'm going to buy one of these?

[TDKPE]

It's got a 4 hp [3 kW] motor, which at full load and 80% efficiency and 80% power factor (both assumptions, but pf may be much higher), it would run at 19.5A at 240V at full load.  While you're not likely to run it that hard, it's possible.  And there's the little issue of start-up current, which for an induction motor is typically 4-8 times rated full load current.  Common inverse-time circuit breakers can handle substantial overcurrent for short duration (the higher the overcurrent, the shorter the duration before it trips), but a 20A breaker may not hold, even a 'high magnetic' type (higher magnetic 'instant trip' threshold).

My 3 hp Unisaw, at 12.4A rated at full load, starts and runs on a 15A circuit, which I know because I retasked an existing 120V circuit to run my saw when I first moved here.  Never tripped the breaker.  But when I built my basement shop, I ran a 20A circuit for all my 240V machines.

If it were me, I'd run it on what I have, and if that didn't work, run a 30A circuit for it. The worst that happens is that it trips the breaker on start-up.  But if it will start and run on a 20A circuit, it'll probably be just fine.  If it has both a start and a run capacitor, power factor will be as high as 98% (like my Unisaw with Marathon motor), and current draw will be low, like 16A at full load, which would mean a 20A circuit is adequate, the way a 15A circuit was (barely) adequate for my 3 hp Unisaw.

It's a motor circuit, which technically is supposed to be sized to a minimum of 125% of the motor's full load current (from the NEC Table 430.148*), and a 20A circuit for a 4 hp motor would be undersized.  But you're not a factory or commercial installation (like a cooling tower motor on a roof), or a pool filter pump, or whatever. 

*The table doesn't list 4 hp, but averaging 3 and 5 hp gives 22.5A, and 125% of that is 28A, so a 30A circuit would be indicated.  If this was an industrial installation, at least.  There's more to it (there's always more to it), but that's as much as you probably care to know.

Edit: Poking around a little, it looks like that motor has both a start and a run capacitor. The run capacitor reduces the current across the board by correcting power factor (basically the out of phase 'magnetizing current' which is just bouncing back and forth between the utility and the motor but doesn't actually drive the load, and doesn't show up on your residential electric meter), so that would explain why the 4 hp motor can run on a 20A circuit. Same reason my 3 hp motor can run on a 15A circuit, at only 12.4A nameplate full-load current, and I never push it that hard anyway.

[JohnnyEgo]

I run my A3-41 on a 20 amp circuit, and have not had any issues. There is a sheet of paper that ssays in giant font to run it on a 30 amp circuit. But when I called Felder USA, the tech I spoke to said it would run just fine on the 20 amp circuit. And it has.

[MyKidsDad]

TDKPE and JohnnyEgo, thank you both for your replies, they were very helpful.

[acanthuscarver]

Does anyone here happen to have, or happen to be familiar with, a Felder Hammer A3-41? I've been emailing a Felder rep and specifically asked him if a 230V 20A circuit would work to power the machine. His reply was less than a straight-forward answer to me. 

Here's my question (black) and his answer (red)...
I’d like to confirm that a 240V 20A circuit is adequate to power the A3-41? That's perfect, the machine requires 230V 30 amp but you can go down our up either way. 

I don't know how it's ok to go down if the machine requires 30A as he says. So, can anyone tell me if I'm fine with a 20A circuit, or if I need to try and upgrade to a 30A circuit if I'm going to buy one of these?

I've got an A3-31, and am familiar with the A3-41. They'll run on dedicated 20-amp circuits without trouble. If you have something else on the same circuit, you'll want to jump up to 30-amp.

Chuck Bender

[MyKidsDad]

I've got an A3-31, and am familiar with the A3-41. They'll run on dedicated 20-amp circuits without trouble. If you have something else on the same circuit, you'll want to jump up to 30-amp.

Chuck Bender

Thank you Chuck, I very much appreciate your response.