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Thread: Hammer A3-31 Jointer/Planer - Required Current Rating for Circuit: 20A or 30A?

  1. #1
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    Question Hammer A3-31 Jointer/Planer - Required Current Rating for Circuit: 20A or 30A?

    Okay, so this has gotten almost humorous the more Ive researched it.

    The question is simple: What sized circuit does the Hammer A3-31 need?

    So, from calling Hammer, my local Hammer location, the documentation that came with the machine (see attached image) and various folks around the net, the Hammer A3-31 requires a 20A, 25A or 30A circuit. I have heard all three. I have definitely heard a 20A circuit recommended more than any other but it's just hilarious there seems to be no standard.

    Where I get confused is when I start trying to logically figure it out myself. You see, in my mind, a 3000W motor shouldn't draw more than about 13A.

    P = I * V ---> 3000W = I * 230V ---> I = 13A

    And Im assuming even with a motor startup current that shouldnt go over 20A which would be a 65% spike.

    BUT, the back of the machine oddly lists 19.8A. Is that listed number supposed to be the highest running current draw? The highest spike for motor startup? Some made up number?! lol Im not sure.

    I just can't get past why a 3KW motor would need a 25A or 30A circuit. Any ideas from those with electrical experience would be much appreciated.
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  2. #2
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    Motor input power (watts) = volts x amps x power factor x efficiency. Euro motors are typically nameplated for output watts and it looks like yours is. 3kW output is 4hp, and the 19.8 amps max lines up with that.

    I would expect inrush current to be in the 150 amp range, well within what any of the suggested breakers will tolerate.

  3. #3
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    Here in Australia, my A3-31 (silent head) runs happily on 15 amps, as does the K3 slider. Only the N4400 bandsaw requires 20 amps. All were installed and approved by Felder.

    Regards from Perth

    Derek

  4. #4
    For what its worth, I am operating a SCM FS 41e, 16" jointer planer, rated at 21 amps on a 20 amp 240 volt circuit and have had no issues. Its rated by SCM as a 4.8 HP motor. I should mention that I have measured current draw on machine while under load, and in jointer or planer mode, it seems to be in the vicinity of 13 amps. That is with a full width (16") piece of cherry run at about .015 inches (roughly 1/64") cut depth. I would expect that more aggressive use of the machine would push it up in current draw, but I don't use the machine that way.
    Last edited by Phil Gaudio; 07-26-2019 at 8:14 PM.

  5. #5
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    Oh yea, I should have mentioned too, I have a Hammer N4400 and itís been on a 230V/20A for years and Iíve never had any issues and I was under the impression that ran the same motor as the A3-31.

  6. #6
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    If this is single phase then you should have 240 volts not 230. This reduces load to 12.5 Amps continuous. 125%. of 12.5 is 15.6 amps. But, I doubt the saw is continuous running so you can use 100% breaker loading. I would upsize the supply line to 30 amps to allow for breaker heating with all the starting cycles per hour. I am sure that will be more then 12 per hour.
    I doubt you can easily find a 25 amp breaker in America. Even if you do I do not think #12 wire is allowed at 25 amps. Depending on run length, upsizing to #10 wire will cost under $20
    Last edited by Bill Dufour; 07-26-2019 at 9:09 PM.

  7. #7
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    The safe bet for a machine like this would be a 30 amp circuit, IMHO. It's not materially much more expensive and you know you've covered things.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  8. #8
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    I put in a 30 amp circuit but I've read that people are using 20 amp with no problems. The manual says the electrical connection "safeguarding" is 16A. Not sure what safeguarding means.

  9. #9
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    Hi, in Canada the A3-31 is limited to a 20 ampere circuit.

    Mine has been on a 15 ampere circuit for 12 years.

    The 16 ampere safeguarding is 16 amperes in the EU.

    Mine is limited to a circuit capable of no more than 5KA, which isnít an issue at home......Rod

  10. #10
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    20 Amp for me here in Western USA. Has not ever tripped the breaker.

  11. #11
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    I used a 20 amp circuit, so far it is fine and thatís what the FELDER sales representative said I needed for A3-41.

  12. #12
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    Quote Originally Posted by Pat Rice View Post
    I used a 20 amp circuit, so far it is fine and that’s what the FELDER sales representative said I needed for A3-41.
    Yep, the folks at the Felder/Hammer location in West Sacramento told me the same. They said thats what they run theirs on in their showroom floor for demos. While I was there I confirmed it. BUT, they also looked like the never actually use most of the machines on their showroom floor, so that still left a bit of doubt in my mind.
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  13. #13
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    I have a A3 41 being delivered in a few weeks.

    When I talked to the electrician I hired to install 220v in my garage, I gave him the specs for the motor. He said a 20 amp circuit was appropriate. Thatís what he installed.

    Bob

  14. #14
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    Quote Originally Posted by Bob Hinden View Post
    I have a A3 41 being delivered in a few weeks.

    When I talked to the electrician I hired to install 220v in my garage, I gave him the specs for the motor. He said a 20 amp circuit was appropriate. That’s what he installed.

    Bob
    you will be fine. My A3-31 and my KF500 Pro both run on 20a circuits. Think they both have the same 4hp motor. My MM16 however requires a 30a circuit with its 4.8hp motor but it too can run on 20 in a pinch.

  15. #15
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    Congrats on the new machine. I know you will enjoy it. I have that same motor on a Felder combinaton machine and a dust collector. They were set up and tested by Felder using a 20 amp circuit for each. Never had a problem.
    Eugene in NC

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