Switch for multiple machines on one outlet

[philshevlin]

I don't know the terminology, so a search hasn't been helpful.


I want to build something that works like a 110v power strip, but for 220v. Its for a welding cart with 3 machines. All similar amperage (same plug 6-50p). Only one machine will be operated at a time.

1. Would I need to have some type of 3 way transfer switch to guarantee only one machine at a time gets power? Or can I rely on the breaker if there was accidentally too much draw?

2. Does something like this already exist? If so, what's it called?

Any other suggestions?

Thanks!

 

[TTMotorsports]

Just have 1 plug. Unplug one and plug in other.

 

[Whitworth]

I know they have power strips with individual switches on each receptacle. As far as I know, 120 volts, don't know if 240 volts version exists.

Search "power strips" in McMaster-Carr website.

 

[alfredeneuman]

I know they have power strips with individual switches on each receptacle. As far as I know, 120 volts, don't know if 240 volts version exists.

There are NO plugstrips for 50Amps of any voltage

 

[sberry]

Just run 1 at a time. Even if they are on wouldn't hurt. Depending on models they may be designed to run 2 to a circuit. When you do that have to run 50A wire for 50 breaker. Some machines could be 30 but would b limited to the use of 1 and need a 10 wire with multiple outlets.
Since this was equipment and not building wire we might consider some latitude in methods.

 

[Zeke]

You can do what you want with a electrical box big enough for 3 plugs. You will likely need to make you own custom front plate. The switches on the individual welders are the only switches you need. IMHO.

And I can understand why you might want to do this if one of the the cord plugs from the welders is different like an older welder might have.

I thought this was interesting even though it isn't what you are looking to do:

 

[philshevlin]

Thanks y'all.

When my laziness reaches the point where I want to spend the time and money....

 

[fitter30]

Circuit breaker box using one main 50 amp breaker and three 50 amp 2 pole breakers wired to three 50 amp or less outlets. Then you get the protection of the main power and individual protection of your equipment.

 

[philshevlin]

Hoping to attach it to the side of my large HF welding cart. That sounds great, but wouldn't fit anywhere.

 

[Bert_]

Circuit breaker box using one main 50 amp breaker and three 50 amp 2 pole breakers wired to three 50 amp or less outlets. Then you get the protection of the main power and individual protection of your equipment.

If it's all 50a plugs what is the point of all the extra breakers? They don't provide any extra protection. Just a lot of extra stuff. It might make sense if you wanted say a 20 amp outlet also but if it's all 50s then forget the extra breakers. You could do the same thing just by jumping three outlets together.

I think sberry would be correct that you should have full 50 amp conductors if there is to be multiple outlets.

 

[PNWguy]

It would all depend if it's in your garage or at work.

If it was me, in my garage... I'd have a cord with a female end going to the welding area. I'd put the same male plug on each welder, and simply plug in the welder I wanted to use.

This, actually is what I do and it works fine. When I'm welding close to the wall, I just plug into the wall. If I'm more than 10' away, I plug in the extension cord and plug the welder into that.

 

[philshevlin]

It would all depend if it's in your garage or at work.

If it was me, in my garage... I'd have a cord with a female end going to the welding area. I'd put the same male plug on each welder, and simply plug in the welder I wanted to use.

This, actually is what I do and it works fine. When I'm welding close to the wall, I just plug into the wall. If I'm more than 10' away, I plug in the extension cord and plug the welder into that.

This is what I do. But apparently, I'm getting too lazy for that.

 

[driftpin]

What about a knife switch which sends power to one-side or the other? That's only two, but choose the ones you use the most, and leave the third unplugged. I'm no electrician so I'm not-sure that's to NEC.

 

[sberry]

Bert hit it. Use the 50 that feeds the circuit and a heavy wire to the jbox, you could use lighter wire to each outlet. Combination use cant overheat the main wire. Any welder that comes with factory 50 end can be on 50 circuit.

 

[sberry]

The combination of outlets can't overload the main wire. I did this for a bud, he had a buzzer to outlet with 6 or 8 wire. He was out of spaces, bought a 375 plaz and a 211 we removed recept, put a jbox to 2 outlets with 10 wire. He could run them both, could still use the buzzer if needed but leaves the 2 new machines plugged in .

 

[Milton Shaw]

I have found that you can run two machines on one circuit at the same time but you cannot use both at the same time. The "idle" current draw is such that probably three or more could actually be on but not being used without overloading the circuit. For instance to tig weld in the root weld and then stick weld the cap without having to go turn machines on/off.

 

[alfredeneuman]

What about a knife switch which sends power to one-side or the other? That's only two, but choose the ones you use the most, and leave the third unplugged. I'm no electrician so I'm not-sure that's to NEC.

It's called a transfer switch, and are recognized by the NEC.
They are most often used with generators.

 

[sberry]

You could run 2 211's or less from 50

 

[theoldwizard1]

It's called a transfer switch, and are recognized by the NEC.

They fall into the category of "safety" switches. Never seen a DP3T except on low voltage and power.

 

[SGKent]

probably would not be considered NEMA friendly but maybe 3 50 or 60 amp amp 230V contactor switches triggered by a 24V 3 way switch, or 3 separate on- off toggles. You'd need a grounded box safe enough not to accidentally get damaged if something banged into it, 3 contactors, a 230V supply and ground, the trigger switch(s), a 24V source such as a 24v transformer, 3 sockets, and the patience to make sure everything was installed carefully and in a way it could not ever short out. Also the box would have to have an exterior disconnect on it. But it could be done. I understand that plugging and unplugging has its own risks. Otherwise 3 separate circuits and cords. All the welders I've known have a different station set up for each welder type, and they rarely went back and forth between types on a job. You'd have to choose a switch that did not allow any chatter between contactors - meaning a rotary might not have a clean on-off sweep so that two contactors might still be engaged simultaneously for a split second.

You could use something like this to switch each contactor. But you would have to build it in a sturdy case because nothing like that appears to be out there.

contactor example - just make sure it is for at least 50 amp.

 

[alfredeneuman]

They fall into the category of "safety" switches. Never seen a DP3T except on low voltage and power.

That's not what you asked though
EDIT: Some ATS units are able to switch between 10 loads

 

[Bert_]

Lots of complicated solutions for a simple problem...

I'm still a fan of the simple solution, 3 outlets 1 circuit. No transfer switch, no contactors, no nothing, just three outlets hot all the time. The only thing special is that it needs to be full size wire, no wire reduction for welders.

Even if you grow a third arm and managed to run all three machines at the same time the worst thing that happens is it trips the breaker.

 

[sberry]

The only thing special is that it needs to be full size wire, no wire reduction for welders.

Yes, the feed wire. You could reduce going to each outlet and in this kind of setup an 8 wouldn't bother me as the main considering the duty of most of these machines. It would make for a wire nut connection of 3 10 to the 8 or even 12's depending on the machines.

 

[sberry]

I just wired up outlets for a new synchro, the owner is a minimum type guy when it comes to wire to say the least but I put 2 with 12 but they are not daisy chained, both wires go to the 30 breaker.

 

[TS3g]

Lots of complicated solutions for a simple problem...

I'm still a fan of the simple solution, 3 outlets 1 circuit. No transfer switch, no contactors, no nothing, just three outlets hot all the time. The only thing special is that it needs to be full size wire, no wire reduction for welders.

Even if you grow a third arm and managed to run all three machines at the same time the worst thing that happens is it trips the breaker.

I agree with Bert. I did just what he described on my HF welding cart. I made my own triple gang box with a 25' HD extension cord coming out of it that I plug into the wall outlet when in use. My MIG, TIG, and plasma cutter stay plugged into the box at all times. I'm only person, so can only use one machine at a time. Even if all machines are turned on, two at idle and one at full tilt, the load is less than my breaker is rated for.