220 for Welder

[Jack]

Scully is wiring my garage for a Millermatic 180 (give the guy work if you can!).

We ran wire for a 50 amp circuit, in case that is ever needed. These small welders use 50 amp receptacles and cords. The funny thing is the input power is only rated to "230V, 21.7A, 60Hz, Single-Phase," so it seems we should use a 30 amp circuit breaker to protect the welder. If it should only pull 21.7 amps, is there any reason the welder will set off the 30 amp breaker in normal use?


Welder: http://www.millerwelds.com/products/mig/millermatic_180_autoset/

[Ramsport59]

I'm subscribed to this, I was wondering the same thing. I have 60amps out to the garage and I was told I'd need a minuim of 100amp service to be safe.

All I'd need is the welder and over head flouresent lights on.

Rick

[dutch boy]

I have the same welder, and have been running it off of a 50 amp circuit for over a year now.... no issues. I dont think you will have any problems, and like having the 50 amp service just in case the welder were to ever surge and not pop the breaker

[atjeep]

I doesn't hurt anything to have a circuit rated much higher than is necessary.
I ran a 50A circuit for my welder.

[Jack]

I doesn't hurt anything to have a circuit rated much higher than is necessary.
I ran a 50A circuit for my welder.

You are a smart guy, but I think this is false. :happybear:

[phillyzj]

there is no chance under normal circumstances that a 30A breaker will blow with a welder rated for 21.7 A. In fact, peaks over 30A may not trip the 30A breaker.

With the appropriate wire, a 50A breaker and a 50A outlet should be fine, even with a lower load.

Think about it, you run a 1A laptop off a 15-20A outlet and it's just fine, right??

[atjeep]

You are a smart guy, but I think this is false. :happybear:

While I do not claim to be an electrician, I am responsible for configuring power for thousands of computers. We use circuits up to 30A 208V single phase and 60A 208V 3-phase. In my work, having a breaker with too high a rating has not been an issue. We run 2A-4A loads on 30A circuits all day long, 24x7x365.
It is when I exceed the breaker rating that I have some 'splainin to do.

[Jack]

Think about it, you run a 1A laptop off a 15-20A outlet and it's just fine, right??

Ya felt like you had to take it to computers for me to understand, huh?
:D

[54ford]

If you read the manual for the welder it says a 25 or 30 amp breaker atleast that is how i read it. I have ran mine on a 50 amp breaker and no problems That is what was in my garage and i never changed it.

[lowdown]

He can run the wire that's good up to 50A but install a 30A breaker. Personally, I would want it protected @ 30A and not 50A so it couldn't fry itself if it were to pull over its normal peak load. Philly is partially correct..in that, if just for a fraction of a second, the welder pulls over 30A, the breaker will not trip. That's correct due to how the breaker is designed. For example, fan motors, mainly the big ones, pull a huge amount of current at start up. The breaker will not trip because that large current draw only lasts a fraction of a second. If the motor were draw over the breaker's rating while running, the breaker would trip and it should. The rating of the breaker should be close, I think the rule of thumb is 20%, over the peak amp draw of the load; in your case 21.7A. Bottom line, put a 30A breaker on that circuit.

[ehall]

safe practice is to over-spec wiring and under-spec breaker

[mopar]

as said above ... over rate the wire ... and national electric code states 20% over rate your breakers and then round to the higher breaker

use a 30 amp




that being said mines on a 60 :p

[Jack]

Killer. I am sure I would be fine with a 50 AMP, but I am gonna try the 30 amp 1st. I got the wire run for a 50, if I ever need it.

[Broncolou]

A 30 amp breaker will be fine. The 50 amp stuff is used for overkill to keep the heat down at the connection points. The receptacles on high load devices are what sees the most problems when they happen. The larger the plug/receptacle the more surface area for connections causing less heat under high load. The breakers will all "trip" at the same short circuit amperage but will not trip the same under malfunctioning(but not shorted/short circuited) loads. Try the 30 and if it trips go to a 50 or a 40 if you like. I am sure you will rarely,if ever run it up to the 21.7 amp rating unless you are welding at max capacity. HTH
Lou

[phillyzj]

Ya felt like you had to take it to computers for me to understand, huh?
:D

haha, it was just the value i had in my head from doing a power study at work :cheers: