[dunkster]

Looking for a little knowledge on breaker sizing. As title says, machine is a synchrowave 350 LX. Being home based, I'm limited to 230V service. I'm assuming it's 230 as my multi-meter reads 240/242 range. I replaced the run years ago, which I'm 95% sure is now #6 wire...if anything else it's #4, not #8. Total run length is about 26 to 28 feet, outlet to breaker. Currently it's on a 60 amp breaker that was originally for my mig. Though it's been a while, pretty sure it trips after a few minutes of anything over 170A output or so. I think max I could ever want out of this machine is about 250 amps, never the full rated 350. I'm aware a 150 and maybe even a 130 amp breaker is a bit much for the #6 run, but know (at least think) I can go more than my current 60. According to the 250's requirements, a 110 amp breaker is safe on a #6 run of up to 158 feet, however I don't know if that directly translates over to the 350 or not. Basically, I'd like suggestions on the biggest breaker I can safely use with a 28 foot long run of #6 supply line, keeping in mind I'm looking for a maximum of 250A output.

And if anyone can explain the whole power correction factor thing, I'm all ears...no wait, eyes.

Thanks guys.

Here's both the 350 & 250 per manual req's:

[Louie1961]

Power factor correction is basically a big capacitor inline with your power supply. You will draw a lower max amperage with PFC, but you also draw the same load at idle. Without PFC, your machine will draw nearly nothing at idle and will have a greater max amp requirement.

The national electric code lets you overrate a breaker relative to the size of a conductor based on duty cycle. The syncrowave 250 can run on 6 gauge wire and a 110 amp breaker, because it has a 200 amp, 60% duty cycle. You could probably do something similar, but I wouldn't recommend it. You run the risk of starting a fire since your Sync 350 has a MUCH higher duty cycle (300 amps at 60%). Your machine is not going to time out or have a thermal shut down as fast as a syncrowave 250, and that could be enough to fry the wires, and start a blaze. That being said there are a lot of people who run 330 A/BPs and syncrowaves on a 50 amp circuit without too much trouble. They simply blow the breaker when the push it too hard. In your case, I would try to keep the breaker closer to something appropriate for the wire size.

[Poland308]

Breakers are in the system and sized to protect the wire in the circuit only. Technically. Line size is critical. As a general rule the actual amperage you will be pulling should be approximately 80% of the rated capacity of the breaker. Like Louie said there is an entire section in the electrical code specifically about welders and derateing breakers and line size. If you don't have any friends who are electricians to ask I would recommend buying an electrician a 6 pack and have him run the numbers for you in the code book just to get an accurate idea.

[Otto Nobedder]

dunkster,

A couple of things I'd look at before modifying anything...

Starting at the machine (unplugged, of course), open the connection panel and inspect the direct input connections. Do you see discoloration (brown or black) where the wires are screwed to the input board? Clean them, and retighten them.

Break down the plug that goes to the wall outlet, and check for the same condition.

With the breaker CONFIRMED off, check the same condition inside the wall outlet.

These issues are remarkably common.

While inspecting the wall outlet, check the condition of the insulation. If the insulation is cracked/damaged, it's a sign of overheating in the wall wire run, and a sign of hazard.

This next step is riskier, so don't do it unless you're qualified, and that is to pull the cover off the breaker box and make the same inspection where the wires come out of the breaker, as well as the neutral and ground wires at their respective busses. Also, look at where the main feed wires attach to the buss bars (but don't mess with these... that's "licensed electrician" work).

Steve S

[ldbtx]

dunkster,

A couple of things I'd look at before modifying anything...

Starting at the machine (unplugged, of course), open the connection panel and inspect the direct input connections. Do you see discoloration (brown or black) where the wires are screwed to the input board? Clean them, and retighten them.

Break down the plug that goes to the wall outlet, and check for the same condition.

With the breaker CONFIRMED off, check the same condition inside the wall outlet.

These issues are remarkably common.

While inspecting the wall outlet, check the condition of the insulation. If the insulation is cracked/damaged, it's a sign of overheating in the wall wire run, and a sign of hazard.

This next step is riskier, so don't do it unless you're qualified, and that is to pull the cover off the breaker box and make the same inspection where the wires come out of the breaker, as well as the neutral and ground wires at their respective busses. Also, look at where the main feed wires attach to the buss bars (but don't mess with these... that's "licensed electrician" work).

Steve S

Very good point, Steve. That's a real common issue with high draw equipment. Under heavy load conditions, the 60 Hz frequency of the AC current will literally vibrate the set screws away from the wires and cause the connection to loosen marginally. This results in higher resistance and heating.

I once replaced (when I was working as an electrician years ago) a 4 wire, 3 phase run of 4/0 THHN that was nearly 500' long. The breaker lugs had loosened over time and the heating had burned the insulation off all four conductors about a foot down into the conduit. We had just a few feet left on each of the 500' rolls to make the full run. It was a very costly job for the facility, but it was a frozen food plant and a rush job.

[motox]

years ago i had trouble with my 250 tripping the breaker
at higher amps. problem was ground (earth) wire at panel.
snugged it up, problem solved.
i was advice from electrician on job.
no 6 pack required this time
craig

[dunkster]

Thanks for the replies guys.

Steve, I can tell you the wires coming out of the breaker are fine...had the cover off minutes before I started this thread to check my wire size and everything looked good in the box. As soon as I have some time, I'll drag the machine out and check everything else. I expect it all to be fine since I rarely push this machine, mainly because I hate having a complete shutdown halfway thru a weld and everything that comes with it. That and I'm a stickler on tight electrical connections, all of which I've gone thru before at some point.

I'm thinking I could get away with somewhere between an 80 to 100 amp breaker since I usually weld no more than 4 to 6 inches continuously, especially higher amp stuff. Before I decide though I'll find the definitive tipping point of the 60 in there now (been a while since I've pushed it) and try to talk to some electricians. I'm just looking for a tad more juice without worry of a breaker popping.

[Tom Osselton]

I have a water cooled Miller 351 and have no problems running it on 220. I'm still running beads, well when it warms up again.

[dunkster]

What size breaker is it on Tom?

[Tom Osselton]

I just put on a 100 amp and called it a day.