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Generator to run tig welder

thermite

Diamond
As usual you totally missed my point. My point is that just because you and some guy from Montana aren't huge fans of Generac generators doesn't make them bad generators. More bloviation from termite.

I DID point out that "Generac" just by itself - isn't the whole picture. Had you paid attention.

Generac distributes a LOT of "branded" goods.

PRODUCES far fewer. Bid-package engineering thing.

The likelihood of your 17.5 kVA. fifteen years in use .. and the OP's one even being related, let alone identical, is far from 100%, even if his one is not new, either.

Their full-sized residential units, 35 kVA and up - are better-built, too.

Have to be.

Folks with bigger homes who buy those have spent more money, are more likely to have used the services of contractors, and usually have good Lawsters.

Even so, NO "Generac" is in the Big Leagues as top tier gen sets go.
 

BT Fabrication

Hot Rolled
Joined
Nov 3, 2019
I just bought a 17500 watt generator that puts out approximately 78 amps, however the biggest plug is a 50 amp 230v plug and another one is a 30 amp 230v plug.
Looking at the electrical diagram both hots are on the same line, so I want to join them back together so I can give my Dynasty 300 the 61 amps to run at full capacity.

My thoughts are also to use it to run my welding shop since I just experienced 5 days without power.

I wire my machines in the shop all the time as well as having to wire them when I take them out to jobsites, so I know not to kill myself, I also know how to not over load the generator as well and both plugs are on circuit breakers as well.

I'm also thinking that once my amp load exceed 60 amps that the 30 amp breaker will trip which would give me enough power to run some lights and one welder.
Any thoughts of why I shouldn't tie my phases together ?


only reason I wouldn't, what happens if it back feeds the 50A through the 30A connector.......... fire waiting to happen. thats why you run one conductor only.
 

Big B

Diamond
Joined
Jun 26, 2009
Location
Michigan, USA
Here is how I would approach this. Someone please correct me if I am wrong.

Think of a generator being hooked up to a breaker panel with one wire feeding a leg with a 30 amp breaker and the same wire feeding a leg with a 50 amp breaker. In this case you could hook both hots together with no problems. They are already hooked together before they feed the breakers.

Now as to generators, most of the ones that I've dealt with either have two or four field coils. Most of those have two field coils and they only put out one phase. The ones with four field coils have two use two of the coils for one 120 volt feed and two coils for the other 120 volt feed. The advantage to having four field coils is that you can run them at half the rpm's of a two field generator. But it you tie them together you could very likely burn it out from the field coils working against each other or being out of phase with each other. The two coil generators are like the breaker box that is fed by a single feed wire.

With my old Coleman generator there is one set of wires feeding a single 240 volt receptacle with two outlets. I wired a pair of 240 volt plugs with pigtails to a small breaker box and a 6 ga extension cord coming out of it with a range outlet on the end. If I just used one of the small 240 volt outlets it would probably melt it down when I'm running a lot of loads but this allows it to use both outlets instead of one.

If you take the cover off and see that both outlets are fed by the same hot you can combine them. They are already combined inside and then split to both outlets.

I hope this helps.
 

Portable Welder

Cast Iron
Joined
Jan 9, 2015
Location
Milan, MI
Thanks for every ones tips / recommendations, I have the ability to kill the 200 amp breaker and lock the box so there's no chance of back feed.

I dont have the generator yet, there's a 150 day delay to get it, however, looking at the electrical schematic on line, its the same phase of power for both the 50 and the 30 amp plug !
 

BT Fabrication

Hot Rolled
Joined
Nov 3, 2019
just think of it this way. the power hot feed goes out through the 50A breaker then back feeds through 30A because that is the path of least resistance, it will melt everything as its is most likely sized to handle only 30A and not the heat from 50A returning to the neutral if that makes sense. doesn't matter that its hooked together inside. the weakest point will burn first and possibly take the generator coil with it.
 

scsmith42

Aluminum
Joined
Jul 28, 2020
Location
New Hill, NC
I just bought a 17500 watt generator that puts out approximately 78 amps, however the biggest plug is a 50 amp 230v plug and another one is a 30 amp 230v plug.
Looking at the electrical diagram both hots are on the same line, so I want to join them back together so I can give my Dynasty 300 the 61 amps to run at full capacity.

My thoughts are also to use it to run my welding shop since I just experienced 5 days without power.

I wire my machines in the shop all the time as well as having to wire them when I take them out to jobsites, so I know not to kill myself, I also know how to not over load the generator as well and both plugs are on circuit breakers as well.

I'm also thinking that once my amp load exceed 60 amps that the 30 amp breaker will trip which would give me enough power to run some lights and one welder.
Any thoughts of why I shouldn't tie my phases together ?

I would not tie the two plugs back together; but I would check the wiring size for the 50A receptacle to find out if it will support the 78 amps.

NEC has exceptions for welding circuits since they usually don't have a long, steady power draw. Unless you are welding at full current from your dynasty, you should be able to support it on the 50A plug.

I have a Syncrowave 250DX that pulls around 70 amps when I'm TIG welding thick aluminum. I had to upsize the breaker and wiring for it, but the 50A plug and receptacles have worked just fine.

Since your Dynasty is an inverter machine, it will pull less amps than my transformer style.

Best of success to you with your project.
 








 
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