Changing 220v 20 amp to 30 amp?

[BerBer5985]

I have a subpanel in the garage that is rated to 100 amps on the box. It has a 110v 15 amp and a 220v 20 amp breaker on it. The 220v 20 amp controls an old garage heater that will be pulled in favor of a 220v receptacle. I just bought a 220v welder that will be pulling over 20 amps. Is it possible to just swap that 20 amp breaker for a 30 amp? Also how about swapping the 110v 15 amp for a 20 amp?

 

[ecotec]

no and no.

 

[ecotec]

you have to change the wire from the sub-panel to the welder and the wire from the sub-panel to the heater.

UNLESS: the wires were oversized.

 

[Busted_Knuckles]

You didn't provide enough info,.. yes can remove the 20amp 240 volt breaker, and change to 30amp, but what gauge wire is going to the no longer used heater, and how long is the run.

Unless it was oversized originally, you will probably be looking at running a larger diameter wire to the welder plug, which if I recall, the 20amp and 30amp plugs are different as well (Im not an electrician, but Im sure one will chime in soon). So in the mean time, measure the distance from the sub panel to where your receptacle for the welder will be and tell us what gauge the wire is.

 

[ecotec]

i am a journeyman inside wireman and have been an electrician 16 years.

 

[Busted_Knuckles]

i am a journeyman inside wireman and have been an electrician 16 years.

Well then, see Im half right.. just got the time wrong.

 

[Aceman]

no and no.

you have to change the wire from the sub-panel to the welder and the wire from the sub-panel to the heater.

UNLESS: the wires were oversized.

i am a journeyman inside wireman and have been an electrician 16 years.

Have you looked at 630.12(A) and (B)?

 

[sberry]

What model is the welder?

 

[BerBer5985]

It's the new Eastwood mig 175. I needed something with more power than my Lincoln sp135. They had a great deal and they seemed to get good reviews. Comes with the spoolgun too for $499 with free shipping.

 

[sberry]

That machine will probably run fine from a 20A breaker, if it trips and this is a dedicated circuit with 12 wire it could use a 30A breaker. Its duty cycle is low, the wire can be undersized. Some allow 14 for use with 30A but even though under some conditions its legal doesn't make it a great idea. Personally the wires are so small they don't make for great connections at the outlet and V drop becomes a possible factor, these small machines need all the help they can get from the input circuit.

 

[ecotec]

that would be less than a minute and a half of welding every ten.

how hard would it be to run some new wire?

 

[sberry]

I believe the duty cycle for that machine is 30% at rated output and the minimum wire size is 14, 12 is a size up, will melt the machine itself into a puddle before it overheats the wire.

 

[BerBer5985]

You guys are def speaking a foreign language here. haha. Ok, I checked out a few things. The breaker from my main box that controls that subpanel is only a 30 amp breaker out the subpanel which has a 15 amp 110v and 20 amp 220. I have a 40 amp 220v empty breaker in my box which was used for the stove before we converted to gas stove. Was taking out the 40 amp and 30 amp main breakers from my box, putting in a 50-60 amp breaker in place of the two and running brand new wire out to the subpanel. Then putting in a 20 amp 110 amp breaker in the subpanel along with a 30 amp 220v volt. Then running the wire from the 30 amp to a dedicated plug where the heater used to reside. Then running new wire from the 20 amp 110V to several new outlets using conduit to give me a couple new outlets i the garage. Am I doing this correctly??

 

[larry_g]

The basic thing you have to consider in this problem you propose is that the breaker is there to protect the downstream wire. So to answer your origional question we must know the wire size that you have existing. If your pushing the limits then wire type and length come into the answer. Anyone here that has given a yes or no answer is just making wild guesses as they do not know the wire in question, they are only assuming that this was once done correctly.

lg
no neat sig line

 

[BerBer5985]

ok...to make a long story short. The house was built in the late 60' and the subpanel and garage heater came with the house when it it was built. I will check wire size, but technically if I change the breaker and wiring coming from the main panel to the subpanel to the correct size I need if I need to change it, can I do what I just said?

 

[BerBer5985]

Also, the subpanel is only 10 ft from the main panel. How would I determine the gauge wire running from the main panel to the subpanel?

 

[sberry]

You going to pipe or cable? I believe 6 to 60A with cable, for sure 50A with 6. 6/3 with ground.

 

[BerBer5985]

You going to pipe or cable? I believe 6 to 60A with cable, for sure 50A with 6. 6/3 with ground.

Pipe or cable? What do you mean? How would I determine the existing gauge of wire that was used before to see if it is correct for what I'm trying to do. If it's not heavy duty enough, can I swap out the cable from the main panel to the subpanel and then from the subpanel to the outlet to a thicker wire?

 

[sberry]

You can always change wire, all wire should be marked with the size on it. As I recall must be marked every 24 inches? Piped wiring systems use individual conductors, a cable has them all together, like a piece of Romex.

 

[930dreamer]

http://en.wikipedia.org/wiki/American_wire_gauge

This might help

 

[Pure Oil]

I did mine from the garage sub panel as a 40 amp breaker & 8 gauge wire in 3/4" conduit & used a hot + hot + ground (neutral not needed) to a NEMA L6-30 30 amp 250 volt recepticle & matching plug (as called for by the welder owner manual). I also ran a neutral wire at the same time although it's not needed right now - but - in the future if I change things around, for something else, the wire will already be there - and if I don't - no problem. Just my 2 cents