Voltage drop scenario/amperage question

I've just wired an external box with 10/3 solid copper 600v. wire with AWG running about ten feet from the panel to an outside outlet. I need to run it 100' to my slab where I weld. I want to use MAINLY a Lincoln SP 175+, and the input amperage on that is 22 amps. Can I run a 100' of 10/3 AWG with stranded wire safely? It's the big yellow one available at HD.

Now, I also have an AC 225 Tombstone that pulls 50-63 amps. How about that one?

I'm probably going to get a gas driven welder/generator in the future, but this is what I have to work with NOW.

Steve

What Leon said about warming up the plugs.

Your #10 circuit should be good for and have a breaker for 30 amps. That is plenty of amperage for the 175, it should be enough to run the Tombstone at 120 amps with 1/8" rod.

#10 wire is 1.018 ohms per 1000 or .2 ohms for your max load. That works out to a 6 volt dr> I've just wired an external box with 10/3 solid copper 600v. wire with AWG

Roy - solid #10 or Stranded #10 or Micro Strand #10 ? Most tables are for solid wire. Resistance drops and flexibility raises in the various types of stranded.

One could even be rich and buy two long welding cables add a ground safety and put that into a cover - spiral or multiple long lengths of melt.

Always options. Could buy two transformers - kick up the voltage to 575 and then the next down to 240. The wires between have to have voltage isolation but the current would drop in ratio.

Now the transformers must be large enough and they are the size of a welder transformer or larger.

You might be able to find two industrial sized ones that are scrapped or just left as they are large.

Gunner likely throws rocks at them cleaning out or building a shop.

Martin

Mart> What Leon said about warming up the plugs.

The wire tables say for 220 volts: 25 amps will drop 2% voltage over 100 ft. with #8 wire. 60 amps will drop 2% voltage over 100 ft. with #4 wire.

Bob Swinney

Now, I also have an AC 225 Tombstone that pulls 50-63 amps. How about that one?

I'm probably going to get a gas driven welder/generator in the future, but this is what I have to work with NOW.

Steve

My mistake on the generator I got - was having multiple 120v circuits. No 220. Hum - wonder if the 120's are back to back. I'll have to check and if so make a '''test rig''' for 220. Hum - need to check the gas anyway.

Martin

Mart> The wire tables say for 220 volts: 25 amps will drop 2% voltage over 100 ft.

with #8 wire.

voltage over 100 ft.

The question was what will it do with 10/3.

At 60 amps you lose only 5.45% or 12 V, for the first few cycles of A.C.

Then as the copper in the cord heats up, its resistance will increase by 0.393% per degree C. Higher resistance will cause:

1) More power to be wasted in the cable which will: 2) Increase conductor temperature, which will 3) Cause higher resistance in the conductors which will: 4) GOTO 2

Eventually, the cord will reach a new equilibrium with lots of power being wasted in the cable and relatively little getting to the load.

Ferinstance at 70 C rise, cable resistance will total about .255 ohms dropping 15 V or 6.8%.

At 170 C rise, cable resistance will total about .334 ohms and you lose

9.1 percent of your power (about 1200 W) in the cable.

Copper resistance is only linear at cool temperatures. As the cable continues to heat, the copper will begin to increase its temperature at a greater rate per ampere. Eventually it will get quite hot and perhaps fail either shorted or open.

You need bigger conductors or more conductors, Bob.

--Winston

I'm going to use the 10/3 for the wirefeed, and buy a gas driven AC/DC welder since I can make money with it doing portable welding. When and if I build the shop, I'll run a new cable of oversized wire directly from the pole.

Steve

Winston sez:: "You need bigger conductors or more conductors, Bob."

That should have been obvious when I showed recommended wire sizes for acceptable voltage drops for the 2 currents stated in the OP.

Bob Swinney

Of course not.

THE EXTENSION IS RUN THROUGH THE HOUSE WIRING IN A 30 AMP CIRCUIT.

I admit I got focused on the OPs question about the 100 ft run to the shop and didn't pay attention to the bottleneck in the house wiring.

Here's why:

As you mentioned yesterday afternoon, NEC has good science that supports "over fusing" in arc welder applications. It is possible that the time averaged current would be low enough to safely run his buzzbox on that circuit without an extension cord and with limited current settings on the welder. That would make the addition of the extension cord the limiting factor, no?

--Winston

That'll work!

--Winston

acceptable voltage drops for

I think SteveB wanted some background information when he wrote: > "The question was what will it do with 10/3."

I can relate to that. It benefits us all to understand *why* a recommendation is made. See, for example:

--Winston

The overcurrent allowance for this installation in the NEC is somewhere around 30% to 50% IIRC (I'm sure Bruce Bergman can jump all over THAT statement) But the same provision that allows the overfusing mandates that the circuit be used ONLY for welders. I take that to mean that the welder is hard wired to the wall.

But if this is a residential application, I would NEVER EVER consider running a bigger breaker than is code legal. It's my family that would live with the potential fire hazard.

PS: Off topic to wiring issues but to the safety point: Yesterday I discovered that a 40 year old gas furnace installation had the furnace gas shut off valve plumbed in BACKWARDS. It allowed gas to continue to feed to the pilot light even when the main valve was shut off. That was a previous owner's handiwork, just never been an issue until I tried to make a repair and removed a fitting with full NG pressure behind it. Major adrenaline rush here!!! Think about the oversized breaker in the OP's house.

W>

....or move to canada and do your heavy welding in the winter. we've already had about 15" of snowfall here in ottawa. lots of snow to melt in the back yard....then there's always the nights in january/february when it hits -35 C (thats....ummmm....carry the 1, divide by the circumference of the earth, plus the root of pi.......... -31 fareheit)

..just a thought. : D

-mark

(...)

Can you make me a deal on a few hundred cubic km of snow, free shipping? We could sure use it in the Sierra.

--Winston in Silicon Valley at +6 C. BRRrrr!

Yes, but if there is a welder plugged in at the other end, that house wiring cable takes advantage of the same exemption.

And 14-12-10 Ga wire are all artificially under rated by the NEC at

15-20-30 Amps respectively. Depending on CU or AL and the insulation temperature class, they are still safe even when run at much higher ampacities than the Code 'allows'.

If you keep the duty cycle down you can run bursts of 50A through #10 wire all day safely - but after 30 or 40 feet (the run between the Main and the dryer outlet you are repurposing) the voltage drop starts being a serious issue. And throwing 100' of SO Cord in the mix really starts to be a problem.

No, there's an exemption for welders and I'm not going to look it up, but it is in that neighborhood. I doubt they'd totally prohibit plug connections, but common sense would require a permanent sign.

But for the 100' run? For a wirefeed one is enough, for the Buzzbox get TWO #10 extension cords, run them in parallel... Solved.

Not backwards. Not an error. Not a handyman hack. And "Full Pressure" is only 4" WC, well under 1 PSI, you can plug that with your finger. If you are running Medium Pressure Natural Gas at 5 to 10 PSI through a house you have much bigger problems, that's supposed to be done for commercial only.

That type of pilot bypass main valve is typical on old appliances, but they should also have a smaller manual petcock on the pilot line. They wanted a way for a serviceman to shut off gas to the main valve (millivolt Penn/Baso B60?) while leaving the pilot lit - some of those furnaces were a bastard and a half to get lit again.

They figured it was safe enough to leave the pilot flow on even if it blew out, with open ventilation around the firebox, open flues and no dampers, the odds of gas from an unlit pilot building up to LEL is exceedingly slim - and without the thermopile generator being hot from the pilot flame there's no way in heck that the main valve can open.

-->--

....

*sniff* ......someone smell ozone?

-m