Welding outlet (Derating?)

[Nhrafan26]

Ok, after reading on here I have noticed mention of welding outlets, and ONLY outlets labeled as such, can use smaller gauge wire for a higher amp breaker?
Is this correct? Reason I am asking is that I want to run a welding outlet over to my garage doors for doing work outside which will be full gauge #6 to 50 amp outlet to cover anything i want to plug in there. BUT I also want to run a welder only outlet to the back of the shop and if I can run a smaller gauge wire and smaller conduit that would help save a little $ and some space.
The run will be approx. 40' in conduit under slab from wall to wall.
These are the machines that would be plugged into the outlet:
What size wire can I use for just this outlet?

Welder #1
Input Voltage: Single-Phase 110vAC or 220vAC (±15%) @ 50-60Hz
Input Amperage: 28 amps
Output Amperage: 10-200 amps AC/DC
No-Load Voltage: 51
AC Duty Cycle (%): 20-80 (80% at 100 amps, 20% at 200 amps)
Post Gas Flow: 2-8 sec.
Pre Gas Flow: 0.1-1.0 sec.
Efficiency: 80%

Plasma cutter #1
Input voltages: 120-240V, 1-PH, 50/60 Hz
Input current @3.8 kW: 120-240V, 1-PH, 25-18.8A
Output current: 15-30A
Rated output voltage: 125 VDC
Duty cycle@ 40C (104F) 35%, 240V 20%, 120V
Open circuit voltage: 256 VDC
Power supply type: Inverter – IGBT

Welder #2
Input voltages: 230V/60Hz
Input current: 21A
Duty cycle: 30% @ 230V/60Hz
Rated output: 130A
Volts @ rated amps: 20
Power cord: 50A 250V NEMA type 6-50P

 

[sberry]

10/30 makes an idea circuit for these machines.

 

[wyliesdiesels]

Welder circuits are wired based on duty cycle.

While its a good idea, there is no requirement to label an outlet fed by reduced sized wire for a welder.

What plugs do these welders have on them?

What are the brands and model numbers?

Since they have different duty cycles its probably best not to downsize the wire.

 

[Fallon]

Welder circuits are wired based on duty cycle.

While its a good idea, there is no requirement to label an outlet fed by reduced sized wire for a welder.

What plugs do these welders have on them?

What are the brands and model numbers?

Since they have different duty cycles its probably best not to downsize the wire.

I wouldn't undersize my welder wiring. If anything I oversize the wire whenever I do any wiring, it's cheap insurance against later requirements. Smaller gauge wire will heat up & cause voltage drop a lot quicker than worse than higher gauge wire. I wouldn't trust whatever welder I have now to have the same duty cycle as one down the road.

 

[wyliesdiesels]

Oversizing wiring, for anything other than voltage drop or ambient temperature, is a waste of money.

U shouldnt need wire bigger than #6 NM or #8 THHN for a welder that has a 6-50p.

 

[rlitman]

Oversizing wiring, for anything other than voltage drop or ambient temperature, is a waste of money.

U shouldnt need wire bigger than #6 NM or #8 THHN for a welder that has a 6-50p.

Neutrals in a 3 phase system may be oversized to deal with harmonics (an obscure reason for oversizing, but one more exception nevertheless).

Yes, your wire gauges are correct for a welder on a 6-50p, but the inverter welders and plasma cutter mentioned (based on the specs provided by the OP) would all run fine on a 30A outlet.

Knowing that, I think if the OP want's to save money, he'd be better served by standardizing on a smaller plug (I use L6-30 for my welder, plasma cutter and tablesaw), and then 10 gauge wire will be more than sufficient without any downsizing by using a 30A breaker. And technically, based on the duty cycles listed, I believe 12 gauge would even be ok, if he wanted to push the downsizing envelope.

 

[Nhrafan26]

After thinking about this for a little bit and reading the responses I think for sake of standardizing everything I'm going to wire both outlets for 50A with a NEMA 14-50R and put plugs on everything to fit.
Question though, can I, by code or legally put NEMA 14-50P plugs on those machines with only 3 wires?
OR would I have to make up an adapter of some sort? I was also thinking of just tapping off the outlet and putting a 30A Receptacle next to the 50A but figured that's probably a no-go as well since POTENTIALLY someone could plug in both at the same time and overload the circuit??
What do you guys think is the best route?
Oh and Wylie, there's a mismatch of plugs on the machines, I want to cut/remove them all and standardize.

 

[wyliesdiesels]

Why do u want to use 14-50s?

 

[rlitman]

Why do u want to use 14-50s?

Ditto. All of the equipment listed above would happily run on 240V. Is there some need for a high current draw device that uses 120V? If not, I'd skip the L14. It's a lot of added expense.

 

[Nhrafan26]

Main reason being my generator uses this receptacle and this would allow me to have a mobile welding setup as well as plug into anything in the shop.
OR would you advise I make up an adapter just for the generator and use a less expensive receptacle/plug combo in the shop?
Like I said just trying to standardize but not wanting to break the bank at the same time either.

 

[pattenp]

Make an adapter for the generator.

 

[sberry]

Agree, make an adapter vs bastardize the plug system so carefully designed for welders. None of the machines will overheat a 10 wire 50A circuit. All but the 250 migs come with a 12 cord.

 

[ishiboo]

With two welders and a plasma cutter, I would assume you enjoy metal fab work. With that said, I think there's a good chance you might decide to upgrade to a larger machine in the future, and going with the same 50A circuit in the back would probably be a better investment than having to change in the future.

Just my $.02.

L6-50s on everything for me. I even have an old dryer I sometimes use in the barn I have a L6-50 cord made for

 

[sberry]

Thi is a do it rigt and do it once issue. Use a 6-50, this is the welder hardware. I am just now getting around to replacing all the boogers I had over the years. They are wired electrically correct but I want the right plug and recept that is sposed to be on it.

 

[wyliesdiesels]

+3 Make an adapter.

 

[Fallon]

I put in L14-50s in my barn & on my welder. It's what is on most generators. My plasma cutter still has I think it's an L6-30 on it, but I made an adapter to connect it to a L14-50.

L14-50 probably is a bit overkill, but I'm fine playing a little extra for the additional few bucks for the extra wire & more complex plug. It is more future proof if I ever want to do something wierd (quite probable) or use my stuff mobile on my generator.

L6-50 properly wired will be just as good & you can easily make an adapter to run your welder off a L14-50 if you need to go mobile.

 

[Nhrafan26]

With two welders and a plasma cutter, I would assume you enjoy metal fab work. With that said, I think there's a good chance you might decide to upgrade to a larger machine in the future, and going with the same 50A circuit in the back would probably be a better investment than having to change in the future.

Just my $.02.

L6-50s on everything for me. I even have an old dryer I sometimes use in the barn I have a L6-50 cord made for

Thi is a do it rigt and do it once issue. Use a 6-50, this is the welder hardware. I am just now getting around to replacing all the boogers I had over the years. They are wired electrically correct but I want the right plug and recept that is sposed to be on it.

+3 Make an adapter.

I put in L14-50s in my barn & on my welder. It's what is on most generators. My plasma cutter still has I think it's an L6-30 on it, but I made an adapter to connect it to a L14-50.

L14-50 probably is a bit overkill, but I'm fine playing a little extra for the additional few bucks for the extra wire & more complex plug. It is more future proof if I ever want to do something wierd (quite probable) or use my stuff mobile on my generator.

L6-50 properly wired will be just as good & you can easily make an adapter to run your welder off a L14-50 if you need to go mobile.

This is why I really do love this site.
That is what I will do, I will put 6-50's on each machine and just make an adapter to plug into the 14-50R. I like the idea of doing it once and done. I'm putting a large plug right between the 2 garage doors so any welding or other large work (maybe even hooking up an RV from time to time) can be done right outside the doors. The other will be in the back of the shop at the end of the workbench so there's no extension cords from the front to the back.

This site and you guys are really helping me plan everything before I go ahead and start doing everything. That's extremely helpful, I already know there's a ton of mistakes I would've made had I not joined here first.

 

[sberry]

This is the code legal and nema way to do it, put proper plugs on the machine and recepts in the wall.

 

[Aceman]

I'm putting a large plug right between the 2 garage doors so any welding or other large work (maybe even hooking up an RV from time to time) can be done right outside the doors.

An RV requires a neutral where a 240v welder does not. You would need a seperate receptacle just for the RV.

 

[Nhrafan26]

An RV requires a neutral where a 240v welder does not. You would need a seperate receptacle just for the RV.

Nope, already said I'm putting in a 14-50R

 

[Fallon]

An RV requires a neutral where a 240v welder does not. You would need a seperate receptacle just for the RV.

That's why I always go for the flexible option even if it costs more in the short run. ;-)

Most RVs only require 30@ but its better to have more capacity than needed than less. Our 17' Casita runs fine on a 15@ circuit unless I'm running A/C, charging a nearly dead battery & doing a lot of other stuff.

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