[Chamerican]

Looking for some electrical advice. I've read through a few posts concerning setting up electrical in a shop but I'm only living in this home for another 2 years (military) so it doesn't make sense to install a series of plugs or run a sub-panel. That being said, I read several people who recommended running 12/10-3 vs 12/10-2 wiring so therein lies one of my questions described below.

I'm considering the purchase of a 240v cabinet saw (10" 3 HP 240V Cabinet Table Saw at Grizzly.com) but don't "currently" have a 240 v outlet. The saw will be located in my garage and I'd like to run a 240v outlet adjacent to the breaker box- also located in the garage. I have no other 240v tools nor do I anticipate adding before I move. I have no spare slots on my panel except that previously had an electric stove with a 240v run from 2-50A breakers that are no longer used. My thought is to use that slot for the 240v outlet.

If I'm only using the outlet for the saw, and nothing else, can I just run 10 or 12/2 for the 5' run of wire?

Is there a reason I'd need to run a 12/10-3?

Do I need to swap out the 50A breakers?

Considering how (relatively) simple the actual running of the wires is...it pains me to pay an electrician a couple hundred $$ unless I really need to.

My plan is to cut a hole beneath the box and run an external conduit to the receptacle location ~3' to the right of the box.

TIA
-Dan

 

[epicfail48]

If you only need 240v out of the outlet, theres no reason to run 12/3, since the extra conductor is only there to carry a neutral leg to tap into for 120v. Id wager that most of the people recommending that you run 12/3 are coming at it from the position that you may as well in case you have anything down the line that you want to plug in that needs that neutral line

If you keep the 50 amp breakers, youll need to do the wiring with 8 gauge wire to meet code, since the breaker size determines the wire size. Sure, youre only going to be plugging something in that draws X number of amps, but the wiring doesnt care about that. The breaker is there to keep the wiring from overheating and catching fire. Swap it with a 20-3 amp breaker, with the appropriate wire gauge and outlet. A 20 amp breaker and 12/2 should be fine for a saw that size

 

[JayArr]

If you keep the 50A breakers you need 6 gauge wire.

The wire size is based on the breaker size, NOT the load. The idea is that if the saw shorts out the breaker has to be the weakest link so that it will trip. If the wire is weaker it will heat up, catch fire and burn your house down.

6 gauge wire will handle 50 amps so that would be safe. I don't see any reason to run a neutral wire.

Wire is cheaper than breakers but if you really want to use 10 or 12 gauge wire you can swap out the breaker to match. I would go 30A for 10 gauge and 25A for 12 gauge.

Here's a chart. Wire Size Chart

 

[NoThankyou]

OK, here is the rule. The current capacity of the circuit breaker can not exceed the current capacity of the wire. Circuit breakers are intended to protect the wiring and prevent structure fires. Check with NEMA for the actual numbers of amperes.

Not only do you need to run x/3 but should run x/3 w-G. You really want to make sure that the saw is grounded properly. The reason for the neutral wire is that almost all shop machines these days employ magnetic switches. The magnetic switch utilizes 115 volts for its operation, usually from L1. The function of the magnetic switch is to keep power off during and after a power failure. After a power failure you are required to hit the go button again to restart the machine. You may have to hit the stop button to reset the mechanical action of the switch itself.

BTW - Most Grizzly 230 Volt machines are wired for three phase. When only single phase power is used, two of the legs of the switch are used. To convert a machine to three phase, the motor is replaced with a three phase model and wired to the switch. The power chord is also replaced with a 3 phase power chord. When building hundreds or thousands of machines it is cheaper in the long run.

 

[Rick Christopherson]

Well, at least ya got two good answers before the wheels fell off the wagon.

 

[DrRobert]

The FLA for that saw is 14A . They specify 15A circuit and 14ga wire.

I don’t think it’s big enough. All of my 3HP machine circuits are 20A breaker & 12/2.

This is the way an electrician originally wired my shop.

 

[woodnthings]

I can only tell you what I have done in my shops. My 3 HP motors are on 240 volt, 3 wire receptacles, number 12 wire and 20 AMP double pole breakers. I would replace the 50 AMP breaker and use 12/3 wire to your female plug or receptacle with a new 20 AMP breaker.
BUT be DAMN careful about working inside that box with the supply lines exposed and as close to the bottom slot as they are! I would pull the meter OR cut the power to the panel with the master switch before working in there.
An electrician will NOT charge you more than 1 hour labor to do this IF they are honest. It will take less time than that to do it. That's the safest way to do this.

 

[GeorgeC]

Well, at least ya got two good answers before the wheels fell off the wagon.

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george

 

[Rick Christopherson]

I would replace the 50 AMP breaker and use 12/3 wire to your female plug or receptacle with a new 20 AMP breaker.

What you said is correct, except you need to be careful about terminology. "12/3" in this case would refer to 12 gauge, 3 conductor wire plus ground (4 total), when you actually meant 2-conductor plus ground (3 total).

The reason this is confusing is because flexible cord (i.e. extension cord cable) is identified by the total number of wires--including ground, but Romex-type wire is identified by the number of "current carrying conductors "plus ground".

The OP needs to use 12/2 with a 2-pole, 20-amp breaker to install his outlet.

 

[GeorgeC]

If you do anything other than full code and leave it that way, you are doing a disservice to the property owner and the next renter of the property.

That is NOT the way that a military member should leave a property. The alternative is to remove all that you have done before leaving the house.

Do you have the property owners permission to make any changes. You should have.

George

 

[TimPa]

general rules for installing a dedicated electrical circuit. 1. determine the current and voltage requirements of the load (in your case 14a and 240 vac) - this is a very important step. if you can check the owners amnual, or directly off the unit. 2. size the wire accordingly, using the NEC ampacity table 310.16. 3. size the circuit breaker to protect the wire. 4. install. there are other considerations with wire selection, but will not affect your install.

 

[Rick Christopherson]

Well, at least ya got two good answers before the wheels fell off the wagon.

????????
????????

george

 

[Quickstep]

BUT be DAMN careful about working inside that box with the supply lines exposed and as close to the bottom slot as they are! I would pull the meter OR cut the power to the panel with the master switch before working in there.

I noticed this as well; great idea about pulling the meter of finding another disconnect.

 

[subroc]

I am not an electrician and I don't play one on the internet. The only thing about the OP is removing the 50 amp breaker that is/was servicing a stove receptical and leaving that dead legged. I would think about how I was going to do that. Pulling the 50a breaker and putting a 20a in its place doesn't seem all that confusing to me. Once that is done you have a circuit and a breaker to service the saw. Am I missing something here?

Timely. I just bought all the stuff to put a 20a 220 volt receptical in for a 2hp Dayton motor.
Siemens QP 20a breaker
12/2 Romex
Leviton 20a outlet
Leviton 20a plug
Powertec 71007 mechanical switch, not a mag switch

Anyway, to the OP, good luck

 

[Rebelwork]

Why can't you run a small 50 amp box and take it down from ther.e

 

[PPBART]

...Do you have the property owners permission to make any changes...

If I was the owner of that property I would require the tenant to employ a licensed/bonded electrician to do that job. If he did it without my knowledge and permission, I would be highly pissed! If he did it himself and burned the house down, I would certainly consider him liable.

If it was my house, I'd DIY it without question.

 

[Shop_Rat]

The very worst place to get advice for electrical matters is on a forum that doesn't moderate with professionals.
I've read all of the replies and some of them are correct, some of them are partially correct, and some of them are absolutely incorrect.
Go here, register, get the right advice, and sleep well at night:
Electrical | DIY Home Improvement Forum (diychatroom.com)
If you want woodworking advice, this is a great place to be. If you want to learn how to fly, this just isn't the right venue.

 

[Bob Bengal]

Ditto what @Shop_Rat said. I have registered on diychatroom, largely for electrical issues, I haven't asked a question yet but their electrical subforum is very active with a lot of pro electricians.

 

[Parrdan]

Many different views here. I might as well get my feet wet. 12-2 wire is rated for 20 amps and 10-2 wire is rated for 30 amps. 12-2 and 10-2 wire has black and white insulated wires and a bare copper neutral wire. 12-3 and 10-3 have black red and white insulated wires and a bare copper neutral wire. The saw you are looking at is rated for 14 amps. The questions you asked were

(If I'm only using the outlet for the saw, and nothing else, can I just run 10 or 12/2 for the 5' run of wire?

Is there a reason I'd need to run a 12/10-3?

Do I need to swap out the 50A breakers?)

So... It is ok to run 12-2 wire to the outlet. There is no need to run 12-3. Replace the 50 amp breakers with a 20 amp double pole breaker.

 

[Rebelwork]

F he's just gonna use the 50 amp break slot, just change it to a 20 amp and be done. As long as it will accept the wire...