240-Volt Wiring For Woodshop

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  #1  
Old 07-27-14, 09:53 AM
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240-Volt Wiring For Woodshop

When it comes to wiring, one can never be too safe. I've spent the weekend looking through posts and think I know how to safely complete the 240-volt wiring in my basement woodshop but thought I'd post my plans just to ensure I'm not making any mistakes. I currently have four woodworking machines requiring 240-volts that I'd like to wire up:

1) 1.5 HP Dust Collector: 5.5-amp (manual specifies minimum 15-amp circuit)
2) 1.5 HP Jointer: 7.5-amp (manual specifies minimum 15-amp circuit)
3) 3 HP Planer: 15-amp (manual specifies minimum 20-amp circuit)
4) 2 HP Shopsmith Mark 7: Hasn't arrived yet and no access to manual. Advertising states it works on 15-amps @ 120-volt so @ 240-volt 15-amps should be sufficient for the DVR motor.

I plan to hang these on two 240-volt 20-amp circuits. Both will use a Siemens Q220 20-amp 2-pole 240-volt circuit breaker. Wiring will be 12-gauge. The first circuit will have a single 20-amp receptacle. I plan on using this circuit exclusively for the dust collector since it'll be running when any of the other tools are operating. The second circuit will have two 20-amp duplex receptacles in the same junction box. This allows me to plug in the jointer, planer, and Shopsmith all at the same time and provides one extra outlet for a future tool. In general, there would never be a reason to have two of these tools running at the same time.

Does this all sound like a good safe plan?

One followup question since everything surrounding 240-volts comes across as confusing in the message boards. I would have a total of 4 outlets on a single 20-amp 240-volt circuit. There is nothing unsafe about operating multiple tools on the same 240-volt circuit at the same time, correct? If the load becomes too high, the 20-amp breaker would trip protecting the circuit. There's no other hidden dangers, are there? The requirements for the Shopsmith and jointer seem small enough that they could probably run at the same time on the same circuit and I'm wondering if this is safe.

Thanks for any info!
 
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Old 07-27-14, 10:24 AM
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Welcome to the forums! No voltages were shown for items 1-3. So assuming 120 volts. Your cable to the shop should be a 4 wire cable in a subpanel with a separate grounding buss and grounding rod. I would use one 15 amp 240 volt breaker for the ShopSmith. As voltage increases, amperage directly decreases, so the current draw would only be 7.5 amps. You will need to rewire it for 240 volts, which I am sure the directions will indicate. I would dedicate two circuits for general work receptacles and one 15 amp for the dust collector. A 20 amp circuit would handle the rest.
 
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Old 07-27-14, 10:35 AM
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Voltages for all items are 240-volt. The woodshop is in the basement near the main panel for the home so the circuit runs would be short. In general, items 2-4 (jointer, planer, and Shopsmith) would never run at the same time. My primary concern was to finding out if all three could be on the same circuit without issue and if by chance two did get switched on at the same time, there would be no additional danger. From what I think I've read in the forums, 240-volt circuits at 20-amps or less have the same rules as 120-volt circuits. You can put multiple outlets on them, they can be used at the same time, and if the circuit overloads, the breaker trips. It's only 240-volt circuits at 30-amps and greater that have to be dedicated to a single tool?
 
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Old 07-27-14, 11:03 AM
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Good clarification. For the items not used at the same time, you can run them on the same breaker as long as you use 20 amp breakers or less. I run my compressor on its own breaker, 'cause you don't usually control it individually like you do a saw. Delta 5hp Unisaw, radial arm saw, and jointer are all on one circuit. Welder is 50 amps so separate run for it.
 
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Old 07-27-14, 12:09 PM
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There's no reason multiple 240-volt tools can't run at the same time on the same circuit, is there?
 
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Old 07-27-14, 12:52 PM
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There's no reason multiple 240-volt tools can't run at the same time on the same circuit, is there?
Plugs and receptacles should be matched to the amps of the tool and breaker to max amp rating of the receptacle rating. Therefore if you have an a tool that draws 13 amps or 12 amps it should be on a 20 amp breaker. If you have a 13 amp and a 12 amp tool if they both were used at the same time the 20 breaker would soon trip. A 30 amp beaker would be over sized for the tools and the plugs and receptacles they should use.
 
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Old 07-27-14, 01:34 PM
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Plugs and receptacles should be matched to the amps of the tool and breaker to max amp rating of the receptacle rating. Therefore if you have an a tool that draws 13 amps or 12 amps it should be on a 20 amp breaker. If you have a 13 amp and a 12 amp tool if they both were used at the same time the 20 breaker would soon trip. A 30 amp beaker would be over sized for the tools and the plugs and receptacles they should use.
Yup, I understand that part. I was basically going for something along the lines of... if you have hypothetical 6-amp and 8-amp 240-volt tools on a 20-amp 240-volt circuit, all is good running them at the same time since 6+8=14 < 20, right?
 
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Old 07-27-14, 01:44 PM
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Yes, that should be okay but just remember the motors draw three or more time the amps when starting but then if you don't have a helper no problem.
 
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Old 07-27-14, 01:51 PM
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Yes, that should be okay but just remember the motors draw three or more time the amps when starting but then if you don't have a helper no problem.
Thanks for the info! I've been trying to figure out if a 240-volt circuit operates in identical fashion to a 120-volt circuit in regards to these matters.
 
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