220V electrical lines, what amperage?

[Yuri Sadykov]

I was working on two 20A 110V circuits in my shop for some time. It is not
that bad but I always felt limitations in choosing my tools. Finally, I need new
cyclone dust collector and needs on better electrical lines. Even those (CD)
which will be enough for me require 30A because they suck too much power on
start up. I am deciding on getting two 220V circuits. Will 20A be
enough? I know it is enough for DC, but what if I decide to buy, let say
Hummer 4HP table saw, will it work on 20A? I do not want overspend (who
does?) for overkill, but definitely would be good to have some room ...
What your thought? My shop is small one car garage and I do not run many
machines simultaneously. Basically, one machine + DC.

[John Donofrio]

Hi Yuri,

When I built my shop last year, I put several 20A 220v circuits in for tools. One of them was dedicated for dust collection, which I have not purchased yet. In the little bit of research I've done on dust collection so far, I've realized my options would be far greater if I had made that dedicated circuit 30A. 3hp is about the limit of 20A. You'll still have decent options but they'll be somewhat limited.

Hope this helps.

[EDIT] Oh, and I forgot to mention that #10 wire is not that much more than #12 cost wise. Of course this depends on how much wire you need. The breakers should be the same cost. You can have 10 gauge wire and use a 20amp breaker on the circuit but not 12guage wire with a 30A breaker. That would be bad.

[Wade Lippman]

There is no way to be sure.
Rule of thumb is that 3hp will run on 20a, but not always.
My new Griz 3hp Cyclone says it requires a 40a circuit, though most people get away with 30a.
Highly unlikely a 4hp will work on 20a, but maybe.
The safe bet is to ask the manufacturer.

Assuming you have adequate power (and it is prudent to check that first...) A 30a circuit isn't much more work than a 20a circuit. You can always put in #10 with a 20a breaker and change to a 30a if you need to later on. A 40a circuit IS more work; #8 just isn't user friendly.

[Yuri Sadykov]

Yes, I know that cost wise #12 vs #10 wire is not is not big, but ... If I will use 30A, I need to put corresponding receptacles, conduits has to be bigger, #12 wire is already stiff and #10 will be even worse, and that lead to additional difficulties. In the end it really makes it harder. I know for sure that one line used for DC (thinking Grizzly G0449 2 HP) will be enough. As for other, dedicated for machinery ...
Strangely, I checked spec on Hammer K3 saw, and they do not provide numbers on amperage, just say 4HP.

[Andy Fox]

If you're thinking 4 HP+ tools might be a possibility, I'd just go ahead and run #10 gauge wires for 30A/240v. Might as well put 30A breakers in too, since the wire is rated for that.

Tearing out #12 gauge wiring and replacing it will be more expensive than just running #10 gauge in the first place.

Edit:
See for an amp draw/HP chart: http://frentzandsons.com/Hardware%20References/MrFresonsHdweRef.htm

Edit2:
Even more detailed and precise: http://www.cerusind.com/catalog/documents/calculators/MotorEngineeringFormulas.pdf

[Carl Beckett]

If you're thinking 4 HP+ tools might be a possibility, I'd just go ahead and run #10 gauge wires for 30A/240v. Might as well put 30A breakers in too, since the wire is rated for that.

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This was my solution. I started out running a mix of 20a and 30a. But then added a 5hp upgrade option. Then thought, what if I rearrange, then I no longer have the 30a in the spot I need it. So I just pulled #10 and put 30a on everything.

Then there was a question on whether the cord from the machine to the wall was protected....... (i can sometimes do this with a breaker, but only if I have the 220 stuff on a separate breaker each, which I do not)

We will see what Mr Inspector thinks......

[Bud Millis]

For what it costs, I use 10 gauge for all 220 circuits and 12 gauge for all other circuits. My thought is it will meet my needs now and in the future; electrical safety aspect and over all just a good investment.

[Jim O'Dell]

I did the same thing Bud did. I even have my 1 1/2 HP contractor saw on a 30 amp line. I'd go ahead with the 10 gauge and go ahead and use 30 amp fixtures. The breaker is for safety of the wiring so you don't burn the house down right? It isn't sized for covering a problem that might crop up in the motor. Do it once, do it right. Jim.

[Jim Andrew]

Running 10 gauge sounds great, until you buy a tool that requires 8 gauge.

[Richard Jones]

...........Then there was a question on whether the cord from the machine to the wall was protected....... (i can sometimes do this with a breaker, but only if I have the 220 stuff on a separate breaker each, which I do not)

We will see what Mr Inspector thinks......

If the machine is pre-wired with a cord-and-plug, Mr. Inspector doesn't have anything to do with it. The presence of whatever equipment you wish to utilize is not mandatory.

[Carl Beckett]

If the machine is pre-wired with a cord-and-plug, Mr. Inspector doesn't have anything to do with it. The presence of whatever equipment you wish to utilize is not mandatory.


Well of course the equipment is not all pre wired with 30a plugs. Some is 2hp. Some is 3hp. A 4.5 hp. A 5 hp. (5hp is the biggest on these circuits). So all the plugs had to be changed to 30a to plug in anywhere. In order to protect this section, the machines would all need the wiring between the plug and the motor upgraded, no? Or maybe since these are not buried in and insulated wall, the insulation factor is different and still ok for the higher current?

(now to be clear, I wired all 110 with 12ga, and all 220 with 10, and changed the 220 machine plugs to 30a. But I don't actually know if this is legit)

[John Lanciani]

You're doing fine Carl, don't over think it. The function of the breaker ends at the face of the outlet, the code does not cover cord and plug equipment. For what it's worth, I run my 5 hp bandsaw on a circuit protected with a 20 amp breaker and I have never had a trip. The breaker does complain a little sometimes (it buzzes on startup) and I should probably change it out to a 30 (the circuit is wired with #10) but then I'd have to change the receptacle and all of the cord caps on the other machines that share the outlet. I like 6-20 cord caps, no twist locks in my shop ever.

[Bernie May]

Similar to several above, I used 10 gauge for all my 220 lines. I use 20 A breakers and outlets for all equipment 3 hp or less. For the electric heater I used 30 A. For the line that has multiple outlets on it I used bigger boxes where there is a line in and a line out to make it easier to work with the heavier gauge wire. I plan on upgrading to a bigger bandsaw and bigger jointer/planer and will switch out those breakers and outlets when i do. Doing it over again I would have used 30 A breakers and outlets everywhere.

[Rod Sheridan]

[QUOTE=Yuri Sadykov;2041675]Yes, I know that cost wise #12 vs #10 wire is not is not big, but ... If I will use 30A, I need to put corresponding receptacles, conduits has to be bigger, #12 wire is already stiff and #10 will be even worse, and that lead to additional difficulties. In the end it really makes it harder. I know for sure that one line used for DC (thinking Grizzly G0449 2 HP) will be enough. As for other, dedicated for machinery ...
Strangely, I checked spec on Hammer K3 saw, and they do not provide numbers on amperage, just say 4HP.[/QUOTE

Yuri, I have a Hammer B3 Winner and an A3-31 J/P.

In Canada, they are limited to a 20 ampere feeder, I happen to run mine on a 15 ampere feeder, it's been 4 years, some day I may upgrade to a 20 ampere circuit...............Rod.

[Jim Andrew]

Didn't even consider that I might need more than a 30 amp circuit when I got my G9983 widebelt sander, it is 5 hp, but the book said I needed a 40 amp circuit, so had to install a 40 amp breaker, #8 wire, to run the thing. According to the gauge, it never approaches 40 amps.

[Darius Ferlas]

Yuri, I have a Hammer B3 Winner and an A3-31 J/P.

In Canada, they are limited to a 20 ampere feeder, I happen to run mine on a 15 ampere feeder, it's been 4 years, some day I may upgrade to a 20 ampere circuit...............Rod.

All my 220 is 12awg, except for one, which is 8awg. I got it for free so why not.
I was running my A3-31 on a 15 amp circuit briefly and there were no issues, though I decided to feed through the 8awg and a 20 amp breaker. Well, I managed to trip that breaker a couple of times.

[Rob Russell]

Yuri,

I like the various discussions about wire gauge, but that's not your biggest issue. If you just want to run some "normal" (ie., not huge HP) 240V machines, (2) 20A 240V circuits will work. And yes, before someone posts - you can have multiple machines plugged into that same circuit. If you run 1 circuit for the dust collector and the other circuit for the table saw/jointer/planer/what-ever-other-240v-machinery-you-have - that's fine.

Your larger problem is that you can't run exposed NM-B cable (aka "Romex") along stringers on the wall in a garage. You have to either fish the cable through the walls or run surface-mounted raceway (aka conduit).

Rob

[Chris Friesen]

If surface mount isn't a problem, I'd say run 20A circuits for what you plan to use, and then if you ever need bigger you can add it later without digging into the walls.

[robert morrison]

As most have said 20 amp is enough for most equipment up to 3 hp. 5 hp reens a 30 amp.

The griz 3 hp cyclone rated at 22 amp use to recomend a 30 amp circuit and now they have changed the recomended amperage to 40.

The same 22 amp motor on a shop fox cyclone ia still showing the need for a 30 amp circuit. I have never tripped a 30 amp breaker with a 3 hp 22 amp shop fox cyclone.

Cost of heavier gauge wire isn't the issue as much as fitting the wire into the box. Use the largest deepest double gang boxes that you can buy to make it as easy as you can.

A 5 hp planer, tablesaw, or wide belt sander is the only other reason you might need a 30 amp cicuit besides a dust collector.