Electical Question (Amps & Phases)

[Steve Canada]

Hey all,

Just need some electrical help. I picked up a cheap Delta 34-814 Unisaw. It's 5hp, single phase, 230a. My garage is a 60amp service and has 3 individual 220a breakers, with single outlets tied to each.

Do I just need to change the breaker for this saw? Do I have enough power?

Lastly, the actual plug has rounded prongs, my outlets have the more T shaped inputs.

Thoughts / Advice ?

[Mike Davis NC]

Hey all,

Just need some electrical help. I picked up a cheap Delta 34-814 Unisaw. It's 5hp, single phase, 230a. My garage is a 60amp service and has 3 individual 220a breakers, with single outlets tied to each.

Do I just need to change the breaker for this saw? Do I have enough power?

Lastly, the actual plug has rounded prongs, my outlets have the more T shaped inputs.

Thoughts / Advice ?

230v not 230 amps

You will need a separate 220v breaker for the saw.
I would provide a new 220v outlet for the saw.
60 amps should be plenty if the saw and some lights are the only things in use at one time.

Your single outlets -- do you mean 110v outlets? if so you should have single 110v breakers for each circuit. Not good to run 110 circuits off a 220v breaker.

[Steve Canada]

Thx.

Yes I have 3 seperate outlets, each fed by a single 220v breaker. So my breaker box contains 3, 220 breakers. Each feeds it's own outlet.

I was just confused about the 230 motor spec and my 220 breakers. I will need to run my 220 D/C at the same time.

All the 110 stuff has it's own breakers and stuff.

[Mike Davis NC]

There should be a plate on the motor that says how many amps it will draw. Size your breaker a little higher.

[Dave MacArthur]

there are 3 threads on this active right now, which would be of benefit to you to read. Try a search for 3hp 5hp motor circuits with my name, and you'll see good info. I'm on a laptop I can't work the mouse on, or I'd post the link... but lucky to get this mouse to the reply button
Short answer: 5HP you need a 30A circuit on a 10AWG wire. You keep saying 230v (same as 220-240v), but what you NEED to be saying is how many AMPS those 230v circuits have... probably 12ga wire with 20A, which would in all liklihood work fine for your saw without popping, but to be correct you' d be best to run a 10ga wire to a 30A breaker.

[Steve Canada]

Thank you to all who've helped with this.

OK. Some clarity now after having a look.

• The fuse box contains 3 - 240v 20 Amp Breakers.
• The motor on the Unisaw states: 230v / 20 amp draw / 60hz / single phase.

So, I should be good on the power part of things - correct? Plug and play?

Interestingly enough, I acquired this saw from a manufacturing receivership auction. It looks like the saw is equipped with an onboard, aftermarket, failsafe of some kind. It has a big blue reset button on the housing that hits the little blue button see in the pic. It's manufactured by "Telemechnique". Here's a picture with housing off:



Does this addition change anything? Not sure if this is a current management thing or just an onboard breaker.

So my three remaining questions are:

1. Can I simply swap the plug on the powercord to one that matches my outlets?
2. The line in the wall servicing these outlets should be able to handle to load correct?
3. Will running two of the three 240v breakers at the same time put to much strain on the 60 amp service?

[Ron Rutter]

Steve. I think a 20 amp 220volt plug has two flat prongs on the same plane. If your outlets have 20 amp receptacles they should match. That pic shows a pretty fancy controller of some kind. If all else fails got your local electrical supplier & pick their brains. Don't play around if you are not familiar with the equipment & electrical stuff!!
As long as the start surge is not to high 20 amp should be oK.
Cheers. Ron.

[Rollie Meyers]

Steve. That pic shows a pretty fancy controller of some kind.
Cheers. Ron.

That " pretty fancy controller" is a IEC style magnetic starter.

[ray hampton]

I do not think that a 5 hp motor will draw 20 amps--more closely to 40 amps, 1 hp is about 700 watts =apps. 7 amps

[Mike Davis NC]

If the plate says 20 amp run then you will need some reserve for start surge. I would install a new 30 amp breaker for the saw.

As long as the two devices draw less than 60 amps the current service will handle it. Just to be safe I would start the dust collector and let it get up to speed and then start the saw.

[Steve Canada]

What would a IEC style magnetic starter do? It only has a reset switch, but the power runs through it on its way to the motor.

Sounds like I should upgrade the breaker to a 30a 240v breaker.

Thanks again everyone for your guidance.

[Kent A Bathurst]

.......Sounds like I should upgrade the breaker to a 30a 240v breaker..

The experts can chime in here, but my understanding is that, by code, a 20a breaker/circuit can run 12ga wire, but 30a needs 10ga wire. So, if you change out the breaker, you also need to run 10ga wire if you don't already have it [which I doubt you have - would have been no reason to use it for the original circuit].

[Ron Rutter]

Steve. 5hp motor = 28 amps = 30 amp breaker & # 10 wire. Should be OK for starting load.

[Dave MacArthur]

Steve, what Ron said. I mentioned a link to search for, which it sounds like you may not have read.. The entire process of determining the right wire gauge and circuit breaker for a 5hp motor, according to the NEC, is laid out. Here's the link for you:
Sizing Wires and circuit breakers for 3HP and 5HP shop motor circuits


the short answer is 5HP needs 10 gauge wire, and a 30A breaker. There really is no way to be legal with 12ga 20A breaker... sure you can do it, and a ton of other bogus wiring stuff that would never be permitted or pass inspection, and it will work just fine until your house burns down

I've got 3 5HP machines that I want soooo much to just run on my existing 20A circuits. After 15 hours with the NEC, there's just no way to do it, unless I just choose to ignore the code and wish it true...
Good luck

[Jarrett Vibert]

What would a IEC style magnetic starter do? It only has a reset switch, but the power runs through it on its way to the motor.

That starter makes and breaks the motor load from you circuit. The yellow cord that exits that box goes to a start/stop station of some kind not pictured. That station will provide power to the starter's coil on a start button press and "turns on" the saw.

That starter has an overload add on sized to protect the motor from overheating due to applied load. If it trips, (the saw stops while in use) it de-energizes the starter and removes power from the motor. After a short period of time (secs usually), you can press that blue reset button, and continue using the saw. However, if that overload does trip, something is wrong.

Sounds like I should upgrade the breaker to a 30a 240v breaker.

Yes you should.... ...and then upgrade the wiring to a 10awg. The breaker is there to protect the wire, not the saw.