Adding 220v grizzly dust collector

[Johnny Currado]

I currently own a 3 hp Powermatic 66 cabinet saw. I have a buddy selling his grizzly 2hp 220v dust collector. My question is how can I run this at the same time as my cabinet saw?  Do I need to add a separate 220v outlet?  Or can I run them both off the same circuit breaker?  What options do I have?  Thanks!

[Huxleywood]

First look at the motor plates on the saw and DC and determine the FLA (full load amps) adding them tells you your current needs for the two.  Then you need to know what your breaker size is for the circuit you want to use.  

In the end it is a better option to run two appropriately sized circuits but you MAY be able to get away with what you have depending on the current needed and what you have available.

[Johnny Currado]

Awesome. Thank you

[rwe2156]

I run multiple 220V machines off one circuit, but rarely are they being used at the same time.  Not so with a DC so the best thing is put it on a dedicated circuit.  If you have space in the panel, it shouldn't be that hard to run another circuit.

At 220V a 3HP motor draws 11A and a 2HP 7 (768W/220V=A) together that's 18A at full load ratings.  Assuming you have a 20A breaker and 12Ga wire, you will still be under max draw.   Blower amp drawer can vary depending on the setup.  The best way to determine the actual blower amp drawer is with an ammeter. 

I would just try it you'll probably be OK.  The first time you stress that TS don't be surprised if the breaker pops.

[TDKPE]

You might get away with it on a 30A circuit, but highly unlikely on a 20A circuit.  A 3 hp with very high efficiency (percentage of current not making heat) and near-unity power factor (percentage of current not used to create magnetic fields) can be as low as 12.4A at 230V (nameplate values of my Unisaw's Marathon motor) at full load.  But most are higher, with some Chinese motors in the 18A range.  3 hp Baldors of that style, if memory serves, are somewhere in the 15A range. And a machine that is hand-fed can easily be overloaded, pushing the current draw beyond the rated value (starting is just a severe overload as far as the motor is concerned, though very short-lived).

The DC should be started first, since even though it has the smaller motor, is has a much longer start duration at high current (4-8 times the nameplate full-load current), while the saw starts in a small fraction of a second.

But I suspect you'll need a separate circuit in the end, which is a better way to go anyway unless you have a circuit specifically sized for two motors each with independent overload and overcurrent protection, which I don't think that DC has.

[Huxleywood]

At 220V a 3HP motor draws 11A and a 2HP 7 (768W/220V=A) together that's 18A at full load ratings.  Assuming you have a 20A breaker and 12Ga wire, you will still be under max draw.   

You are assuming 100% efficiency on the motors which is essentially impossible.  Most 240v woodworking machine 3 hp motors will run from roughly 13 to 15 FLA.  A 2hp DC will be in the 9 amp range full load.  It is possible one would never have full load on both at the same time but for that hypothetical pair I would want them on a 30 amp circuit IF I was confined to one.  The biggest issue will be on startup and I would never try to start both at the same time (on a single circuit) and would always have the DC running first since it will be the heaviest load on startup especially if the gate is open.

[Johnny Currado]

Very interesting points from all of you and greatly appreciated!  Most likely I will just run another circuit for the DC but was curious if I could upgrade my breaker to a 30amp.  Yes. my powermatic has a 3hp baldor motor rated at 15amps and the Grizzly DC is rated at 12 amps and it has an induction motor.  The DC will be running at the same time as the table saw.  Also curious if I can run a heavy duty extension cord maybe 15' for the DC.

[TDKPE]

Not unless it's 10 gauge copper or heavier.

But there's no rule against using an extension cord, as long as it's heavy enough for the load.  But personally, I'd just run a longer circuit so you don't need to, or replace the cord with a longer one.  You're probably not going to find an 'extension cord', with factory NEMA 6-15 or 6-20 plug and receptacle, anyway.