What wiring do I need for my new dust collector?

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  #1  
Old 01-17-13, 10:26 AM
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What wiring do I need for my new dust collector?

I just assembled a new Grizzly 3hp dust collector.
The manufacturer recommends a 40a circuit, but I have checked around and everyone runs them on 30a circuits without any problems.
The plate says it draws 22a, Grizzly says it is 20a, and I measured it at 19a. I also measured the starting amperage as 140a; and started it repeatedly without incident on a 30a breaker. Square D says a 30a breaker will handle 150a for 4 to 12 seconds without tripping, and the DC only draws 140a for a split second before dropping down to 19a.

I can either put a plug and outlet on it, or hardwire it. It is 15' to the panel, so figure 25' of cable; not much voltage drop.

My understanding is that if I hardwire it I can use#12 wire (1.25*18A, which is below the max of 25a for #12) and a 40a breaker (2.25*18a). So, my plan would be to run #10 romex to a junction box and a #12 whip to the switch box; all on a 30a breaker. Is that okay?
Is MC okay for the whip, or do I need something more substantial? What is acceptable.

I think those values would not be acceptable for a plug/outlet. What would I need there? Would 30a all the way be okay?

Thanks
 
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  #2  
Old 01-17-13, 11:10 AM
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It sounds like a 30 amp circuit would be fine as long as it is dedicated to the dust collector.
 
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Old 01-17-13, 12:10 PM
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Yes, it will be dedicated.
 
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Old 01-17-13, 12:12 PM
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If you need to run wire anyways do you have 240V & 2 panel spaces available? That would cut your demand in half.
 
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Old 01-17-13, 12:33 PM
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The 20a is 240v. Sorry, should mentioned it.
 
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Old 01-17-13, 04:23 PM
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Is the suggestion for a 40 amp circuit in the manual? Have you called and talked to them directly? Perhaps it is a misprint. Sounds like 30 amps should do it no problem.

I like to connect all my machines with a plug. That gives me more flexibility in my shop to move things around.
 
  #7  
Old 01-17-13, 04:59 PM
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Nope, not a misprint. I called and they confirmed it. Now... all the guys in tech support know is how to read the manual, so if it is a misprint they would probably just repeat what is in the manual.
Shop Fox, a sister company, uses the same motor in a somewhat different unit and calls for 30a.

I suspect someone occasionally has a substandard 30a breaker that trips on startup, so to CTA they call for a 40a.
 
  #8  
Old 01-17-13, 05:40 PM
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The plate says it draws 22a, Grizzly says it is 20a, and I measured it at 19a.
You should use #10 wire. A 30 amp breaker is fine if it does't trip. If it trips, it could be changed to a 40 amp breaker, but I doubt it will.
 
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Old 01-17-13, 08:38 PM
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You should use #10 wire all the way. A plug,outlet would probably be preferable, with a flexible cord from the machine to the outlet.
 
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