One word: subpanel. Okay, two words, if you spell it: sub panel.
Solves all of your problems. Since your shop is in your basement and your load center almost assuredly is too, it'll be duck soup.
- - LRod
Master Woodbutcher and seasoned termite
Shamelessly whoring my website since 1999
I just bought a saw and dust collector and they both run on 220. The question I have is, would it be OK for me to use 10/3 and a 30 amp double breaker and put both devices on the same circuit and be able to run both of them at the same time? I would not turn them on at the same time. I would let one get up to speed and then turn the other one on. I want to save the other 5 spaces in my 100 amp sub panel (in which my electric stove is also connected to) I have for lights and other outlets for tools. I am in the process of building a shop in my basement. I just moved into a new home. Thank you all for your opinions.
Grizzly states the following in the manual for their G1029Z Dust Collector: Circuit Breaker: The 2 H.P. motor will draw roughly 12 amps @ 220V. We recommend using a 20 amp circuit breaker. Circuit breakers rated higher will not adequately protect the motor.
I suppose this is true with any 220 amp motor.
Gary
Ooops!! I mean 220 VOLT motor, obviously.
They don't provide overload protection? How did this product get a U/L listing?
There is no harm to running 10/3 rather than 10/2, but unless your machines actually require a neutral you don't have to.
You have not mentioned what the machines draw, but unless they are huge 30a should be plenty; I run both of mine on 20a.
You will have to use receptacles rated for 30a, but other than that it seems pretty straight forward.(though I would rather see two 20a circuits..)
You didn't say what the current ratings were for each of them.
If you do this you need to realize that anything that you hook to a 30 amp breaker needs to be capable of handling 30 amps. In other words all of the wiring, outlets, switches, etc. to your saw and your dust collector needs to be rated at 30 amps as well. That means #10 wire minimum. The reason for this is that the wiring needs to be able to handle a short circuit anywhere in the circuit up to the rating of the circuit breaker that's feeding it. If you use smaller wire and hardware a short circuit will result in a fire and a wood shop is one of the last places that you want this to happen.
I strongly recommend that you put each one on their own breaker which is sized correctly for their full load ratings and wiring. If you bought a sub panel without adequate space you should consider replacing it with a bigger one.
Awright Greg, let's see if an extreme example will clear this up for you. Let's say you could find a 1000 amp breaker and installed it on the circuit in question. Now let's say that something goes horribly wrong with the motor and it starts drawing 200 amps ("cause it found a wrong ground or something) The wiring starts to catch fire along with the surrounding structure, but the 1000 amp breaker (or even the unrecommended 30 amp breaker) thinks everything is just dandy, so it keeps that (or some other excessive) current supplied to the fault in progress. Now if you had minded the warning that 20 amp protection would be correct and proper, it would have tripped and the fire department wouldn't be on the way.
Hope this helps
I said earlier, it is clear that article 430 may simply be too complicated for most folks but I will try again. Start with the nameplate (FLA) rating of the motor. (for example 16a) Multiply this number by 1.25. That is the ampacity requred for the wire. You can use table 310.16 for this (14ga is OK for 20a at 60c)
Now take the FLA and multiply it by 2.5, that is the maximum size of the branch circuit overcurrent device. (40a) Some motors can have higher O/C devices, up to 11 times the FLA but you folks are confused enough. You have only sized the wire and the branch circuit O/C device at this point
NOW you need an "overload" device sized to the motor and some kind of thermal protection (may be the same thing) This is what protects the motor from burning up. Usually that is built into the motor or the equipment the motor is in. It may also be part of the motor starter assembly.
You also need a disconnect.
In your case the motor would have to have a 400a FLA to allow a 1000a breaker and you would need 1500Kcmil wire although most folks would just parallel two
350Kcmil.
You again are confusing overload current and short circuit current. A 500' piece of #14/2 will still operate a 40a breaker with a bolted fault. Shorts are not the problem. If that was true you couldn't plug an 18ga lamp cord into a 15/20a circuit.
He didnt mention with ground, It needs a ground of course. I would check on the distance and current draw with a meter. I use all
12/3 with a ground. All my tools are within 30 feet of the panel. A cheap amp-probe can be a real eye opener on some of these 5 HP motors. It can also be used to tell if the start capacitor is bad on a motor.
I agree that 2 separate circuits is the best way, but you are wrong to say everything must be 30a. It only has to be 30a up to the receptacle. After that, 20a is okay, assuming the machines are less than 20a. (In fact, rereading the code, I am not even sure if the receptacle has to be 30a, though it seems prudent.)
I am the original person who posted this. I have the Grizzly G0444Z 220 volt table saw and the Grizzly 220 volt G1029Z dust collector. Both are rated at 12 amps each. What I would like to do is have them both on the same circuit. I was confused as to using a 30 amp brkr with 10/3 wire. I thought 12/3 with a 20 amp brkr would handle it if I turned each on separately and let it get up to speed before turning on the other. It appears that the best solution would be to wire them separately on their own circuit. It is somewhat confusing to me. Thanks again for your help.
Congrats on your choice of equipment. I too wonder, why couldn't you use the 30 amp circuit as a branch circuit, run it into a subpanel with two 20 amp breakers, and the run your 2 220v 20amp outlets from there.
2X12amps=24amps, well within the 30amp breaker's operating range. Just don't start 'em both at the same time.Gary
It all gets back to whether Grizzly uses internal overload protection in their machines as they should.
On the subject of running 3 conductors + ground. What might you want to run on from there? Someday you may want some 110 at that location. Planning to go back to the panel or just tap into what you've got. I don't think many have kicked themselves because they ran too large or too many conductors the first time. No law against installing a fused switch or breaker at the location if the device needs more protection.
bob g.
jack wrote:
Your dust collector is likely to draw its full rated current most of the time. The saw will only draw max when heavily loaded. If the DC is drawing 12 amps constant and you try ripping that 8/4 piece of oak and the saw hits its 12 amps, sounds like your 20 amp breaker will trip, no?
bob g.
Jim wrote:
I'm certain your description above is well intended; however, what it truly illustrates is your lack of the NEC and it's intended purpose.
The motor you describe could turn into burned toast, the NEC could care less as long as the insulation on the conductors feeding the motor is not damaged.
Circuit protective devices are designed to protect insulation on conductors, not the loads such as a motor, that consume the power.
Overload devices provide that function.
HTH
NO.
One load, one circuit protective device.
HTH
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