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Thread: 220V question

  1. #1

    220V question

    I have a 50 amp 220V circuit in my workshop from which I run a Powermatic 66, delta DJ-20 jointer and a Grizzly 21" 5hp bandsaw (although never at the same time of course). I want to upgrade my 115V dust collector to a 3 hp 220V machine like an Oneida (14.5 amps). My question is: will I have a problem running any one of the tools and the dust collector at the same time on my 50 amp circuit? Appreciate any advice.

  2. #2
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    The problems you're likely to encounter would occur during start-ups, when the load demands spike. I thought I had planned out my 115V 20A circuits well enough to handle this, but I trip a breaker almost every time I startup my 2hp tablesaw. For the 220V needs in my small (just under 800 sq ft) garage shop , I've got three separate circuits - one at 20A dedicated to a Fahrenheat 5000W heater, one at 15A dedicated to my DC, and another one at 15A for running my jointer or bandsaw (and eventually a better tablesaw).

  3. #3
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    What Amps do the other machines draw?

  4. #4
    No, no problem at all.

  5. A 3hp machine should be good at 20 amps, and a 5hp machine should be good with 30 amps, so you should be fine to run a 3hp DC at the same time as any of the other tools. Unless you outfitted your 66 or DJ-20 w a 7hp motor or something!

  6. #6
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    With 50 amps AND APPROPRIATE WIRING, you conceivably have enough amperage to run the DC and a tool simultaneously on the same circuit. This is both a math exercise and a wiring exercise. However, it's generally a best practice not to do that and to have a dedicated circuit for your DC that is separate from the one you would be running a stationary power tool on at the same time. One way to do that would be to take the 50amp circuit and use it to power a small sub-panel in the shop. From there, you split it into two circuits with their own breaker to support two 240v tools at the same time. You may need to check code to see if this is permitted if the existing 50 amp circuit only has two hots and a ground...you may be required to have a fourth wire, even though you're using the sub-panel for 240v tools as there may be a presumption that you "could" want to run one or more 120v circuits from that sub-panel in the future and that requires the neutral conductor.
    Last edited by Jim Becker; 11-03-2017 at 7:40 PM.
    --

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

  7. #7
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    Only problem you may have could be if you have a board pinch the blade on your saw or some other problem like that but that is what you have breakers for anyway is un-expected heavy loads. Cold weather you may need to start your saw first as it will have the biggest draw on startup.

  8. #8
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    I would think you should start the dc first because it will take longer to get up to speed and be drawing more amps until it reaches full rpm. Of course the tablesaw motor is bigger and draws more amps so it makes sense to start the most amp motor first.
    If all else fails switch to three phase equipment and use vfds with a slow acceleration setting .
    Bill

  9. #9
    I have 50 amp service into my shop and I run a 2HP dust collector and any of my tools - sometimes multiple tools at once. Never had a problem. Induction motors on woodworking tools come up to speed almost immediately. You'd have to really try hard to start two tools up at the same time. And once they're running, they don't draw a lot of power because you rarely ever load tools to the max.

    The DC is under constant load, but the rest of your tools are not so they don't draw max amps.

    Mike
    Go into the world and do well. But more importantly, go into the world and do good.

  10. #10
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    As a retired EE, I like to at least meet the National Electrical Code, or do better than it, and keep wire and breaker sizes smaller but adequate for the needed tool, for safety reasons. A shorted out 50 amp circuit is going to make for some extreme excitement and probable fire if it's feeding wiring and tools that are not rated to handle 50 amps. It's a code violation to use wiring with an amperage rating of less than the circuit breaker that feeds it. You are doing exactly that when you connect a tool that only requires 20 amps and is only wired with wire that can carry 20 amps safely. If a short circuit occurred in that tool or wire and the 50 amp breaker was directly feeding it, there would be flaming power cords and power tool long before that 50 amp circuit breaker tripped. Smaller dedicated circuit breakers and wires for each tool, rather than a big breaker and "one size fits all" approach is the safe way to do this. Connecting a tool that is wired for, and needs only 20 or 30 amps to a 50 amp circuit breaker is just "looking for trouble" and is an extremely unsafe practice, not to mention, a code violation.

    Why not attach a small breaker panel to the 50 amp circuit and then use smaller breakers in this panel with outlets of the sizes needed to supply the tools and their wiring properly? If you will never run all of the tools at the same time, the total amperage of the smaller breakers can total larger than 50 amps, but each tool and it's wiring will be protected for the amperes that it is rated for. If several tools only need a 15 or 20 amp breaker and the same voltage, you can just use one breaker and plug in the tool that you want to use. You can even have several outlets connected to that one breaker if they are all rated for the same current as the breaker feeding them, so you can leave all of the tools that require the same power to all be plugged in at the same time, but only use one tool at a time.

    BTW The correct nominal voltages for residential power systems in the USA is single phase 240 volts in a center tapped configuration, so the voltage between the two hot wires is 240 volts nominal and the voltage between either hot wire and the grounded neutral wire is 120 volts nominal.

    The 110, 220 voltage nominal ratings of the USA electric power distribution system became obsolete about 70 years ago. If you have measured voltages that low or lower today, you should be talking to your power company to find out why.

    Charley
    Last edited by Charles Lent; 11-07-2017 at 10:58 AM.

  11. #11
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    sub panel

    I had the same issue, wanting to run a 5-hp cyclone DC and an air compressor from a 50 amp breaker in the main panel so I did exactly what you describe. Because of the length of the run I used big copper (6 AWG?) from that breaker to my DC closet and installed a sub-panel. It has separate breakers for the DC and the air compressor.

    DC_air_comp_breaker_box.jpg

    JKJ

    Quote Originally Posted by Jim Becker View Post
    With 50 amps AND APPROPRIATE WIRING, you conceivably have enough amperage to run the DC and a tool simultaneously on the same circuit. This is both a math exercise and a wiring exercise. However, it's generally a best practice not to do that and to have a dedicated circuit for your DC that is separate from the one you would be running a stationary power tool on at the same time. One way to do that would be to take the 50amp circuit and use it to power a small sub-panel in the shop. From there, you split it into two circuits with their own breaker to support two 240v tools at the same time. You may need to check code to see if this is permitted if the existing 50 amp circuit only has two hots and a ground...you may be required to have a fourth wire, even though you're using the sub-panel for 240v tools as there may be a presumption that you "could" want to run one or more 120v circuits from that sub-panel in the future and that requires the neutral conductor.

  12. #12
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    Quote Originally Posted by Phil Gaudio View Post
    No, no problem at all.
    This is been my experience. I run my entire sub panel on a single 50 amp breaker. I routinely run my cyclone, my lights, and 3 hp machine simultaneously.
    "A hen is only an egg's way of making another egg".


    – Samuel Butler

  13. #13
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    I am facing the same issue. I have a 60 amp feed into my shop. I have 2 50 amp plugs off one circuit so I can run 1 welder at a time at either end of my shop. I have a pig tail setup to run all my 220v tools off a 30 amp twist plug. I now need to add my 220v DC. I plan to squeeze another 220v 20amp breaker into my sub panel rather than hook up to the welding wire so I can hook the DC up full time. I think I will be able to run both my DC and a 220v tool at the same time.

    I also have a 10ga feed into my shop to lights and things. My 60 amp feed was probably added to run a welder before me.

  14. #14
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    Lee, 60 amps should provide for the DC and a power tool with no problem unless the combination of both draw more than that. I doubt you'll be using the welder at the same time as your woodworking tools. I would hope so at least.
    --

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

  15. #15
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    If I run the welder then I don't run any other tool at the same time. Reading the forums it seems like my welder likes 60 amps better than 50 amps. People seem to have less issues with a 60 amp breaker rather than a 50 amp. I have an old Hobart beta mig 2510 welder which is a clone of a Miller 250 amp welder.

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