YAEQ - Yet Another Electrical ?

[Jeffrey Schronce]

I have as new jointer. It has a 3 hp, 220v motor (that is very heavy and about broke my wrist today). No plug and they recommend NEMA 6-20P with 20 amp breaker. The only 220 outlet in my shop is 50 A and has a 3 blade receptical. The 50A breaker is completely incompatible with this machine right? I need to install a 20 A breaker and run line to new 6-20R right?
I have never done this before, but my breaker box has plenty of room and is 100 A service. It has the 50 A breaker that goes to outlet that has been used once of an old welder we brought from the farm. There are (3) 15 A breakers.

[Tom Miller]

I have as new jointer. It has a 3 hp, 220v motor

First things first: you suck.

The 50A breaker is completely incompatible with this machine right?

Yeah, I think so. But there may be a couple ways you could deal with it. I wonder if you could replace the 50A breaker with a 20A, and use the existing wire. I don't know if you can get 6 ga. wire into a 20A breaker, but maybe you could pigtail to 12 ga. You'd have to do that at the receptacle, too. This would be the quickest way to get up and running.

Or, you could replace the 50A receptacle with a subpanel, and wire your 20A circuit from there.

I don't profess to know anything about code, so take these hair-brained ideas for what they're worth.

Regards,
Tom

[Jeffrey Schronce]

I am pretty sure I could replace the 50A with a 20A breaker and use the new 6-20R on the end. But as soon as I do this my FIL will need to use the welder for the 2nd time in 6 years (1st time was using it to "weld" aluminum tubing in outdoor chairs. I finally convinced him that while I know nothing about welding his material was too thin and probably incompatible).
Plus the plus is way over on the other side of the shop and the cord on the jointer is about 4-5 ft.

[dwolsten]

If it's not too hard, it'd probably be better to install a new cable from the box to someplace convenient to your jointer. That way, you could keep the 50A outlet for your welder in case you ever use it again, and not mess with a long extension cord.

The reason you need a 20A breaker, from what I've read about 220V stationary tools, is safety: these tools don't have any circuit protection of their own, so they rely on the panel breaker to be the proper size in case you stall out the machine or something, and a fire could result. Having a too-large breaker would remove this safety feature. Other than physical wire size possibly being too large, I don't see any problem replacing the 50A breaker with the 20A one, except for your current outlet being very inconveniently located.

If you decide to use the existing outlet, it should be simple to remove the machine's existing cord and replace it with a new length of equivalent-gauge cord from your favorite home supply store.

[cabinetman]

Jeffrey

Since you like short answers, I suggest you find out if you need a permit in the area where you are. Some permitting requirements mandate a licensed electrician may have to do the work. Doing the work without a permit and having a problem later may invalidate an insurance claim. Nobody likes firemen running around their house.



"I'M NEVER WRONG - BUT I'M NOT ALWAYS RIGHT"

[Kristofor]

I suppose it might be different for some of this heavy equipment, but I had always heard that the breakers/fuses were there to protect the wiring in the wall not the devices attached to it. My understanding was that they were supposed to take care of themself (or not).

I think the thought is that it's okay to slag your stuff but not to run shorted and light your walls on fire. In a similar light it's fine to run a .5 Amp appliance on a 15A circuit, not sure that this is any different than runnning a 20A item on a 50A circuit.

But, of course I'm not an electrician so this may be wrong and/or dangerous

Kristofor.

[maxparot]

Kristofor has got it right the breaker is to protect the wiring and the structure from an electrical fire. The tool should have some sort of fusing or breaker built in. This may be as simple as a breaker on the motor.
So make life easy on yourself and either put new plug end on that matches your 50 amp circuit's socket or make a adapter cable.

[Jeffrey Schronce]

Jeffrey

Since you like short answers, I suggest you find out if you need a permit in the area where you are. Some permitting requirements mandate a licensed electrician may have to do the work. Doing the work without a permit and having a problem later may invalidate an insurance claim. Nobody likes firemen running around their house.



"I'M NEVER WRONG - BUT I'M NOT ALWAYS RIGHT"

As an insurance professional I can state that stupidity is a covered peril! LOL!

But you are right, I am going to get a pro to do the job.

[Jeffrey Schronce]

So make life easy on yourself and either put new plug end on that matches your 50 amp circuit's socket or make a adapter cable.

Adapter cable is an interesting option. Hmmmm.

[crokett]

What I'd do is wherever the actual 50A breaker is I'd add another small sub panel that has a 20A breaker for your tool and then 2 more 15A circuts for hand tools or lights or something. You have 30A free there, might as well use them. Or maybe 20A for your jointer and another 20A for other stuff. You are losing out on 10A though.

[scorrpio]

Yeah, you could simply drop in a 20amp dual-pole in place of the 50, but that would be a waste of that wonderful 50amp-rated wire. If this is a 3+ground wire, you definitely want to put in a small subpanel there, and run a 220v/20amp circuit off it. You could even put a 50amp circuit in there as well, and then you'd be able to use the welder - just not at the same time as jointer.

[Jeffrey Schronce]

Why the subpanel suggestions? I have the main panel right there is the shop. It is 100A and has 3 20A and 1 50A. The 50A is never used. I have plenty of room on the main box to run any additional lines from the main box. What would be the advantage of the subpanel.

You brought up dual pole. And I have a question.

If I crack open my Main Breaker Box and want to add a 20A breaker for dedicated 12/2 line to the jointer, then I would use a single pole right? The dual pole is for situations where there may be two different consumptions on the line, ie oven burner 220 and oven clock/timer 110?

I think I am just going to do the dedicated 20A circuit run to the jointer. As I understand it, I will run green/bare wire to ground, white to neutral bar and black to the back of the single pole 20A breaker. I have determined the type of breaker needed (Murray). I will run the line to a outlet. I am considering a metal outlet box and cover. Any problems there?

[Tom Miller]

Why the subpanel suggestions? I have the main panel right there is the shop.

Uhhh, because up 'til now you were keeping that a secret.

Otherwise, I'd have suggested to just run a 20A from the main to the jointer, like you're thinking.

Regards,
Tom

[Kristofor]

...
You brought up dual pole. And I have a question.

If I crack open my Main Breaker Box and want to add a 20A breaker for dedicated 12/2 line to the jointer, then I would use a single pole right? The dual pole is for situations where there may be two different consumptions on the line, ie oven burner 220 and oven clock/timer 110?

I think I am just going to do the dedicated 20A circuit run to the jointer. As I understand it, I will run green/bare wire to ground, white to neutral bar and black to the back of the single pole 20A breaker. I have determined the type of breaker needed (Murray).

For 220 you need power off of both bars and a combo/double pole breaker so half of the circuit doesn't stay live when half trips. You'll need a black wire from one bus, a red (on mine, other colors may be allowed?) from the other, a neutral and a ground.

I guess the neutral can be skipped if you don't need 110 and 220 (at least that was the case on my old dryer). And apparently in some cases ground can be omitted too as I see 2 prong connectors on some Euro devices, but if the device has it I'd want it to be grounded.

Same caveats as above about not knowing what I'm doing

Kristofor.

[Holbren]

Some touched on good points so here are mine.

1. If you are not familiar with it you may want to get somebody in.

2. Running a 15A tool on a 50A breaker doesn't give you any protection if the fool fails. The breakers will run in excess of max rating for a given period of time.

3. Is the 50A breaker running anything else? It may be there for your AC. I assumed it is already installed in the box.

4. I use the locking NEMA plug (I think it's the number you called out) and they work well.

5. For ease, I put an outlet by my box and use a homemade extension cord to run to each machine. Not the best but the easiest.

6. In the unfortunate event your house does burn down from that wiring, insurance may not pay if there were no permits and approvals.