I am wiring a wood shop and have to hook up a drum sander. This is 230v 1 phase. We are going to install floor boxes for the machines in the center of the work area to avoid cord drops being in the way. This particular machine doesn't come with a cord, though the manual implies that you can wire it with a cord and plug or hardwire it. The owner wants it cord and plugged. It has a 5hp and a 1/4hp motor. All it mentions is to use a UL/CSA listed cord and plug. 430 mentions that to use a cord and plug as a disconnect for motors, it must be hp rated. I can't for the life of me find a 5hp or better rated single phase cord. The owner found another machine (different brand) that is 5hp with a permanently attached dryer cord on it and wonders why that one has it. This isn't an appliance and it falls under 670 which doesn't help either. What am I missing here?
I see your problem
When I look at a 6-50 they just list that at 3HP. The same site has a 6-30 that says 2HPhttp://www.stayonline.com/detail.aspx?ID=4740
They must want the plug to be rated for LRA or something.
All that said I have a 5HP pressure washer that came with a factory installed 6-30. It is a GFCI plug that is "new standard" so it has to be reset after the power is applied so the plug should never be able to be inserted against LRA.
My gut tells me it will work fine. It seems to be part of other pieces of listed equipment. I'd just like to know how to justify it.
I doubt you would have a problem if you also had a disconnect other than the plug. If the plug is your disconnect it needs to have a 5.35 HP rating and from what I am seeing that is probably close to a nominal 100a plug (6-50 is 3HP).
My pressure cleaner has a 2 pole switch with an "off" position marked.
Looking at some of those pin and sleeve plugs, they don't have horsepower ratings. The only ones that do are the ones that have a disconnect switch included. They are incredibly expensive. Anyone else?
I am open to another opinion but I would probably be OK with you putting a HP rated disconnect switching device on the machine and using a 6-30 plug.
Will the circuit breaker in the panel qualify as the disconnect? (within sight and <50 ft). Or, can a disconnect be mounted before the conduit goes underslab?
Another issue I see is that you're going to have a heck of a time finding a suitable cover listed for the purpose for your floor box. Also, a receptacle facing up in the floor of a wood shop can't be too good a thing. A drum sander makes some pretty fine dust. Is this location subject to Article 502?
The panel is in the other room, so that won't work unfortunately. Thomas and Betts sells a tombstone that attaches to a floor box cover plate with a 1 inch threaded nipple. They sell a cover plate for that which will accept the large dryer/range size receptacle. Solves that problem or use the plates with the large threaded plug for a twistlock. In the end I will probably just do it, though with a cord end from Hubbell, not a store bought dryer cord.
As for the hazardous location. I think it might be a stretch, but it might fall under class 2 div 2 G. This isn't a shop that would be producing daily, if it was, not much volume. There will be a dust collection system as well. Its more of a hobby thing at the moment, though it still needs to be done correctly.
I don't see any reason why the disconnect can't be on the machine end of the line cord, attached to or incorporated into the machine.
... but I have been wrong before.
IMHO if you don't need to pull the plug under load (disconnect function) it only needs to be rated for the BC OCD.