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

Safely, yes. Voltage drop: resistance of 200 ft (round trip) of #10 copper is about 0.2 ohms, drop of 0.2 volt per amp or about 4.4 volts at 22 amps -- shouldn't be an issue. It'd be 12 volts at 60 amps or

5.5% of 220V, shouldn't be an issue.

60 A through 10 GA wire certainly would be an issue, at least code wise, seeing as it's only rated for 30 A generally.

Power dropped by the extension cord is 97 W in the first case and 720 W in the second case. That second figure sounds high to me.

Page '3.30' has a table showing ampacities for multiple conductor cables. Table 4 shows 40 A being an upper limit for 10 AWG neoprene insulation at 86 F ambient (or cooler). That's 320 W loss or 44% of the loss at 60 A.

Were I you, I would buy another identical extension cord and connect it in parallel with your existing cord. You'd have 0.10 ohm loop resistance, a drop of 6.3 V or 397 W at 63 A. That should limit power in each cord to 200 W and you get to use the additional 320 W (that would have been wasted as heat in one cable).

--Winston

The buzz box will certainly work, but only up to about half output. As long as your circuit has properly sized breakers i.e. 30A it's safe enough. Since the NEC has an exception for circuits serving electric welders you could over fuse the circuit based on the duty cycle of the welder if that's all it's feeding.

I ran my nominal 100A input Syncrowave on a 30A circuit for around a year before I got around to upgrading power to my shop. Since I was mostly welding 16 GA square steel tubing and only pushing near 1/3 output it ran fine.

NEC Article 630 allows supply conductors for arc welders to be "over fused" based on the welder duty cycle (table 630.11(A)).

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

I think the headroom is worth the US$130. That's just me, though.

''-yellow-jacket-extension-cord-646965.aspx

--Winston

As I wrote this, I was thinking that the wirefeed would PROBABLY work, but the buzz box probably would NOT work. I'm trying to get hold of my union electrician friend, but he is in another city and has not called me back yet. In the meantime, I'm trying to get a handle on what I can and can't do.

Thanks for your input(s).

Steve

For in-building wireing, yes. Codes don't apply to extension cords in open air, far as I know -- but I'm not an electrician. Winston is right, 7.2 watts per foot is a lot and may be too much -- cord might get too hot.

On Thu, 29 Nov 2007 22:09:21 GMT, with neither quill nor qualm, Winston quickly quoth:

US$90 @ eBay US$100 @ Tractor Supply

P.S: Those cords are HEAVY!

He ran 10/3 from the panel to an outside outlet, so that is 30A inside wiring, the only exception is Article 630 if the circuit is only for an arc welder in which case it can be "over fused" based on the welders duty cycle. It's also not directly the duty cycle, i.e. 50% duty cycle does not mean you can run 60A on 30A wire. The table in that article gives the multiplier to use.

Though the duty cycle on the Tombstone is only 20%, so the welder is more likely than the cord to overheat. Disregarding the voltage drop, for permanent premises wiring, a 60A breaker feeding a 20% duty cycle welder thru 10 ga wire would be code compliant.

Good finds, Larry!

Copperrrrr!

--Winston

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

"Pete C." wrote

Good stuff snipped.

Thanks, Pete, and all.

Comes down to this:

The 100 footer will run the MIG fine. It will run the buzz box marginally, and I don't do things that way. I'm going to wire the work area for now with the MIG and a takeoff for 110v. tools. I will never be welding and using the 110 at the same time, so there's little chance of overloading that. My union electrician friend is coming this weekend to do some more work on the new casita to hook up the panel, and wire in the 10/3 10' run from panel to box. He has suggested going to 6 ga. to run up to the shop later, but that will probably involve running another line from the pole. :-( It is what it is. This will get me welding on some things I needed to do yesterday, and get the pipeline unplugged.

And as you say with your Synchrowave, I mostly run my 175 for .065 tube, intermittent welds, so it's well within limits. Just wanted to be sure, tho. Although I can't use the buzz box, now this gives me an excuse to buy one. :-)

Thanks to all.

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.

"SteveB" wrote

Although I can't use the buzz box, now this gives me an excuse to buy

Meant to say buy a gas driven AC/DC welder and generator.

ooops.

brain fart