longer leads for Thunderbolt XL?

[MarcVM]

Would 50-foot 1/0 leads work with the Miller Thunderbolt XL 300/200 AC/DC?
Thank you.

[jwsrep]

Well, do you want the proper answer or the practical answer?

If you plan on welding at 300 ampres then you wll actually need 4/0 cable....yeah I said 4/0 cable...LOL
When sizing welding cable you need to account for both lead and ground. So in your scenario you need to size it for 100' (50' lead/50'ground). Which 100' at 300 amps is 4/0.

Okay now for the practical answer. More than likely (just an educated guess here) you will not be welding at much higher than 150-160 amps (5/32"electrode). In that case 1/0 will be fine. As a suggestion: make up the 1/0 cables and then make up a 10'-15' "stinger whip" with #4 or #2 cable. This way you are not holding onto the heavier 1/0 cable attached to your electrode holder.

[MarcVM]

thanks

Thank you. I appreciate your help.

[Copperdog]

Whip cable

I DO NOT understand this fully, so please explain to me.

I have a Trailblazer 302 that I have 60 feet of 2/0 leads on. I had the same thought of installing a smaller whip to make it lighter to hold all day.
In my mind I think of a water pipe, a 2/0 cable being a 1" pipe and a smaller cable being a 1/2" water pipe. Why would this situation not cause a restriction in the cables and if nothing else make a high heat issue?
The electricity/current has to make a complete circuit, so are we not causing a restriction by doing this? If it will work, I am all for it, the cables are heavier than when I was younger!

Regards and Thank You,

[Archaic]

Whip Cable

Copperdog:

It is always dangerous to try to compare water flowing through a pipe to electricity flowing through a wire, but since you used that analogy I will bite the bullet and attempt an explanation that will make sense.

You have 60' leads, or 120' total. If you had a 1" pipe and ran water through it at 100 gallons per minute at 50 psi at the start you would see that for each foot of run the psi friction loss would be 0.1 psi (note - this is not actual from a chart, just for "example'). So, in the 120' of 1" pipe the psi loss would be 12 psi. You end up with 100 gpm coming out the end of the pipe at 50 - 12 = 38 psi. Now say that you try to run the same 100 gpm at 50 psi through a 1/2" pipe. The friction loss in the 1/2" pipe at 100 gpm is much greater - say 0.4 psi per foot for this example. Or, 48 psi loss in 120' of 1/2" pipe. 50 - 48 = 2 psi.

The reason that you can use the stinger whip is because of the total of 120' of cable you are only replacing a short (10') piece on the end with the smaller cable. In the pipe example above 110' of 1" pipe = 11 psi loss. 10' of 1/2" pipe = 4 psi loss. Total = 15 psi loss which is only 3 psi less than if you had 1" the entire 120'.

This is way oversimplified and electrical resistance and friction loss in water through a cylinder are two completely different animals but close enough for you to think about it and the simple answer is that you get away with the smaller stinger whip because it is short piece of the larger whole. Hope this helps.

[SundownIII]

Seems to me that we forgot to consider Duty Cycle when discussing sizing the cable.

The Thunderbolt 300/200 only has a 20% duty cycle when operated at 300A.

According to my Weld Cable Size chart (Miller's), for a 300A loading @ 10-60% duty cycle, 100' or less (total run) he could get by with #1 cable. Granted, that when you consider a 150' run, the same chart does call for 2/0 cable.

The Thunderbolt machines are not known for being high output/high duty cycle machines.

If you'd like a copy of the chart I referenced, you can go to the "Resources" section on Miller's home page. Scroll down to owners manuals. Download a copy of the manual for the Dialarc 250 AC/DC. Chart is shown on page 11. (Don't know why they didn't include it for the Thunderbolt machines).

[jwsrep]

Seems to me that we forgot to consider Duty Cycle when discussing sizing the cable.

The Thunderbolt 300/200 only has a 20% duty cycle when operated at 300A.

I absolutely did not take that into consideration. Great point SDIII.
I am so used to sizing industrial machines the fact it's a T-bolt shot right past me. Mark me down for an error in the 3rd inning.

[Steve]

Just use the chart in the manual. After a few years of using 3/0 all the way I find it hard to hold up when 8 feet in the air using 1/8 in rods. Thus I use a ten foot stringer of considerable smaller stuff so as to manage better. I do believe short smaller stringers are covered in the books. Just make sure your ground is cold.

[SundownIII]

JWSREP--Rich

No problem man. You're still batting about .999. Even A-Rod would take that.

I'm not even sure the lugs for 3/0 will even fit on the output posts for the Thunderbolt.