220V/30A or 50A for welder (and wire size)

[toyotaspeed90]

I've researched online, and really haven't come across what I've needed.

I've found lots of discussion of Romex vs THHN (and how THHN is ok for 50A at 8ga, and Romex 6ga), but then I can never find context of what the intended purpose is.

I'm looking to wire a 200V in the garage for a welder. Planning on, for now, renting a big mig welder.

I have quite a bit of THHN cable left. This was from the last house when I installed the 220V pool breaker box and then to a hot tub. However, a hot tub doesn't pull power the same way a welder does.

I have 6GA white, 6GA black, and 8GA ground (green) THHN.

I have a spare 30A 220V breaker (and may bump it up to 50A) and trying to figure out if that THHN cable will work for a bigger welder.

This might be overkill - but, also thinking about a separate 220V breaker box (or if it's made, a 220V breaker and outlet combo box)... that way I can have 50A at the main panel, and if needed, switch the separate box between 30A or 50A depending on what welder I rent (and, ultimately, later down the line end up buying).

Thoughts?

 

[toyotaspeed90]

The only thing I've found specially to Welders is, at least wherever the person postin was from, said code allows dedicated outlets for welders to actually run smaller wire than other 220v outlets, as they don't require costantly power in the same manner. No idea if that's true.

As I found elsewhere, 220v code requires 6ga Romex or 8ga THHN. THHN is able to be smaller gauge die to its insulated/heat variance from Romex.

Looks like I'll be fine with the THHN I have. I'll have to see what the store has for outlet/boxes.

 

[Weber Sarge]

Biggest issue is run distance , that determines wire gauge size and type . My 220v drop cord is 50' long and 6ga x 3 conductor , that wasn't cheap but it runs fine with no heat buildup .
Sarge

 

[KLF]

Have you checked the docs for the welder?

 

[woody]

Welder should be a 50A breaker. Period. There is nothing wrong with an over-rated breaker for a welder, since it allows "any" 220v welder to be attached without concerns over breaker size.

http://www.nooutage.com/images/nema-config-1ph-250v.gif

Both of my 220v welders hook up with a 6-50R plug type.

Follow the amp charts for wire size: Ampacity Charts

 

[Helipilot]

What Woody said. I run a Lincoln 255 MIG, a Lincoln 185 TIG, and a Plasma Torch, all on 220/50 amp, 3-6/ 1-8 wires and consider that to be minimum for welding. Do not undersized your wire or breakers.

 

[toyotaspeed90]

Oh I know.

For my situation the run doesn't matter as the outlet will literally be feet from the breaker box.

I can't choose based on welder since I plan to rent for now and then buy layer based on how I feel about what I rented. I have a 110v/140a welder now, but it's not sufficient for what I neex.

The plug I bought I'd a 50a unit and will wire with my oversized THHN wire and for now the 30A breaker.

Now the one thing that makes me wonder....

At least when wiring a car, you don't want to over estimate the amperage since... the protection is based on needs and if you over exert those needs, you want the safety net to take over....

So, for anyone reading this, why would you want a 50a breaker on a system that runs great on a 30A breaker? Wouldn't that give an uncomfortable cushion of protection?

 

[woody]

Based on that logic, every breaker in your home would be sized specifically to the load...they aren't. They are sized "max" for the wiring. 20A or 15A, depending on your outlets and WORST case options.

I don't change breakers because I'm running a chop saw one moment and switch to a 3/8 drill the next.

A 50a breaker is $10...maybe $15. I've bought a few recently. Considering the wire run is a couple feet (mine is as well), do it once and do it right....50a and 6ga wire. Done.

 

[PAToyota]

As Woody implies, the breaker is sized to protect the wiring in the wall - nothing more or less.

Yes, you want to size things appropriately. No need to size a breaker and wiring for 100A when you’re only using 30A. But for something like a welder circuit, I’d go the next step up (50A from 30A) because there is a certain chance you’ll upgrade the welder down the line - or add a plasma cutter or...

 

[toyotaspeed90]

Totally on board. Was going to get a 50a breaker when I bought the outlet, but couldn't recall what kind of box this house has and the photo I had I couldn't quite tell.

The 30A in there is from the PO and, um, some "special" equipment they ran from it. The bank pulled the wiring but left the breaker there. I'll pull it and take it to find a match, but 50a.

 

[LandCruiserPhil]

Couple things to consider here-
►What are the manufacture requirements. Thats all you need. IIRC My Hobart 187 requires 30A using at 22A on highest setting
►If your welder specs requires 50A or 30A that is only needed.
►Using the 60° column on the NEC 310-16 chart (common in most states) 6ga-50A, 8ga-40A, 10ga-30A
►You gain nothing running a 50A circuit for a welder that only pulls 22A on high

 

[PAToyota]

►You gain nothing running a 50A circuit for a welder that only pulls 22A on high

Except not having to start over when you upgrade.

 

[LandCruiserPhil]

Except not having to start over when you upgrade.

Your 50A circuit will also fall short when you go to a tig and need a 90A circuit. I love it when people waste money on there thoughts on future electrical needs. It pays for my Land Cruiser's and my boat named appropriately 'Change Order'

 

[Tapage]

Modern welders are made more efficient and needing less amps ... and this path will not change in upcoming years ..

 

[Weber Sarge]

That is a good point , my Dynasty at wide open only uses 38 amps on 220v . Older transformer units would have used nearly double that draw rate . I can also run up to 110 amps on 115/20 circuits , either stick or tig . That is the reason for my odd cart design - it fits through a 28" doorway easily , is pretty easy/friendly to stairs and has been used in houses before ...
Sarge

 

[PAToyota]

Your 50A circuit will also fall short when you go to a tig and need a 90A circuit.

Nah, along with the 50A circuit for the Millermatic 250X and Hypertherm PM1100, I’ve got the 100A circuit for the Syncrowave 250DX.