Fuses and Welders

[garboui]

Ok, currently my service panel is still on the edison socket screw in fuses. This is something that in the future will be upgraded to breakers and a larger service so please dont give this as the answer to my immediate issue.

I have not had a single issue when running various power tools such as circular says and chop saws (even simultaneously off the same cct. What I do have problems with is when I run my welder (Lincoln SP135), its 115V MIG. Previously on breakers I would have the occasional trip when running fully maxed out for current. On fuses I will pop one even on the lowest heat settings when doing thing gauge sheet metal.

So far I have gone through a few of the standard all glass fuses, and since put in one of the little mini breaker guys. The mini breakers still blow after about 20-30 seconds of continuous welding. I am guessing its the spikes from the switching gear in the welder that cause so much heating in the fuses. I picked up a Buss TC series fuse today thats supposed to be made for more inductive loads. I may see how it does if I get to fixing my drill press stand in the next couple days.

Is there any better, right now, solution that someone has for running a welder off a plug fuse CCT? right now welding is pretty much impossible for anything more than the lightest gauge material.

 

[pattenp]

What's the amp of the circuit and what's the amp load of the welder?

 

[garboui]

Its a 15A cct. The welder is rated up to 20A. Though because the actual current is regulated via a switching supply the average current will be less than 15A as long as im not running it more than 3/4 heat.

 

[pattenp]

That welder calls for a 20A circuit.

 

[Falcon67]

I'd be inclined to build a "suicide cord" to break out the power conductors to see what is really being pulled. I use a Hobart 140 and have never needed to put it on any kind of dedicated circuit. All my shop circuits are 20A, so maybe I've never actually loaded the welder circuit with additional current.

 

[sberry]

Its no mystery here, these little machines always max out a circuit, its one of the things that make them a poor excuse for a welder. Thats not an insult to your machine but there is only so much to get from a 15A wall socket even on a 20A. Run another wire, a 12 from this panel just for the machine and then you can tailor the over current protection for it. No good way around it.

 

[Zeke]

I'm a sometime welder and I find that 115v machines need a healthy circuit to produce any kind of decent weld at any setting. It must be from what was said above, they draw amps just to convert the AC to DC. I know this: if the voltage drops all the time due to inadequate supply, the welder has a had time doing what it is supposed to do.

 

[nehog]

What might help is to use time-delay fuses...

 

[RCStocker]

You need to put in a sub box dedicated to the welder. It is not hard to do but you will need to run the proper size wire to the sub box form the pannel. Now would be a good time to change out and put in a breaker box. It is not all that expensive and long past dooing.

 

[garboui]

I'll have to see if I have a spare to do a 20 or 25A cct to the garage. It will be an easy run since the panel is literally on the basement wall to the house side of the garage. If this is the case I should be home free as a safe temporary solution.

In the future when I upgrade my service the garage will have its own set of breakers out there as the power entry/main disconnect is already in the garage. When this happens I will have all the power in the world, muhahahaha!

 

[wyliesdiesels]

What's the wire length from the outlet to the fuse box. Have u ever measured the voltage @ the outlet when your using the welder? I'm thinking the welder is causing a voltage sag which in turn causes it to draw more amperage than the fuse is rated for!

 

[sberry]

Hard to argue with that.

 

[Gary S]

If it calls for a 20a circuit, just plug it into a 20a circuit. I still don't understand why anybody would even have a 15a receptacle circuit anywhere. They are nothing but trouble.
My welder works anywhere I plug it in, but I have only 20a receptacle circuits in my garage and yard.

 

[wyliesdiesels]

If it calls for a 20a circuit, just plug it into a 20a circuit. I still don't understand why anybody would even have a 15a receptacle circuit anywhere. They are nothing but trouble.
My welder works anywhere I plug it in, but I have only 20a receptacle circuits in my garage and yard.

Gary, did u read the OP? A person like the poster would still have 15a circuits because its a very old house still running off of a fuse box! Plenty of homes still have 15a circuits! Not everyone is financially blessed enough to have newer electrical in their house. I have 15a circuits in my house and I never have problems. But my romex is 12ga on CBs!

I think his problem is a combination of small wire, voltage sag and regular(non slo-blo) glass fuses! Definitely not the system for high current devices like a welder!

 

[EOC_Jason]

Did you check to make sure your connections were tight too in the box and in your plugs? Obviously make sure you throw the power before jabbing a screwdriver in there.

 

[wyliesdiesels]

@Jason- Good idea but I doubt it will help much!

 

[garboui]

Just a quick update. And answer some of the questions above.

The wire feeding the outlet is 14/2 and is only about a 15ft(max) run from the fuse panel to where it is in the garage.

I had gotten around to fixing my drill press cart yesterday. The mini-breaker tripped after the first plug weld @ about 50% power. This was expected. I then installed the Buss TC series 15A dual element slow-blow. Was able to finish the rest of the job no problem. Lets hope it keeps holding up!

 

[sberry]

Sometimes there is no good waty around things, just no shortcut. Find a wire, somewhere you can find 15 ft of good scrap romex, drill a hole in the wall, run this to the panel and hook to unused or underutilized fuse of 20A. People hear me rant about 120V welding machines, half of it is this. Its got no place plugged in to the circuit you have, even a 12 cord back towards the panel from a 20 would be better and suffecient, a short 14 cord to 20A would be better than a constant problem buried and part of the house wiring. Plug in to washing machine circuit.

To add insult to this the welding will suffer cause you got this little machine turned down. Also make sure any lights or other loads are off this circuit you are trying to use.

 

[sberry]

That would have to be one of my first additions to any place I was planning to work for more than 5 minutes especially if I own it. A dedicated wire number 12 to a grounded outlet and or gfci. Some place to plug power tools in to.

 

[garboui]

Was at home depot today pricing out a small panel for the garage. This would replace the main fused disconnect that feeds the house panel and also provide a 240V cct for the garage and 4 20A ccts. To get this in Eaton hardware would be about $130 excluding boxes, romex and outlets which i probably have almost what i need kicking around already.

For the 130 it seems more than reasonable to do this to avoid the headache of fuses and running inside when something does trip. Think I might have to bump this up the home reno project queue.

 

[sberry]

There is a lot of particular code talk on this forum but this is one of the things some of us try to impress a lot, are you adequately serving the intended load, this goes all the way up to service entrance design but also goes to the end of the line and this 14 that is part of the building wiring that likely worked fine before a fuse change has been modified, this circuit isn't designed for this type of load, I am certain someone can translate it into codes, a big one being wire types, methods, who knows how many jboxes etc, even potential back stabbed daisy chain.

You don't need to know much about a code to realize knowingly overloading isn't a good idea.

 

[wyliesdiesels]

....even potential back stabbed daisy chain....

Ewww, I hate it when outlets are "back stab" connected! Seen too many outlets with dangerously loose back stabbed connections!

 

[garboui]

I'd be inclined to build a "suicide cord" to break out the power conductors to see what is really being pulled. I use a Hobart 140 and have never needed to put it on any kind of dedicated circuit. All my shop circuits are 20A, so maybe I've never actually loaded the welder circuit with additional current.

So reviving this thread from the dead I had gotten around last night to see what was going on with regards to the current demand form the welder on the supply side using a current probe.

Below are 3 scope caps of the current waveform created by the welder. Note that the current is in units of 10mV/A and not all 3 waveforms are on the same vertical scale.

Capture 1) medium heat setting on the welder.
Notes: stable arc.


Capture 2) High current setting on the welder (~3/4 of full scale)
Notes: stable arc.


Capture 3)
Low Current setting (~1/4 full scale)
Notes: Unstable arc due to wire size which is the reason for the inconsistent waveform.



On a side note I cam across some interesting info about welder ccts in the IEC. Seems that its a known issue with fuses. The following is a summary of what I understood from the code: Providing that the circuit is dedicated to supplying the welder and that the conductor is adequate for the service requirements, fuses can be sized up to 200% of the rated service capacity.