Service supply lines

[Sberry]

An 8 feeds any machine that comes factory wired for 50A, a Tbolt of that size could use a 10 romex, the allowed 12 is for single circuit in pipe and even though its legal no one really thinks its a great idea.

[dandeman]

An 8 feeds any machine that comes factory wired for 50A, a Tbolt of that size could use a 10 romex, the allowed 12 is for single circuit in pipe and even though its legal no one really thinks its a great idea.

I certainly concur... regardless of any exception allowed based on duty cycle, I can't imagine using any wiring smaller than AWG 8 on a 50amp C/B..

The C/B needs to be properly sized to protect the entire length of the feeder (e.g. nail or other failure causing a hard short in wire at some point in the future).

Electrical fires are so inconvenient...

[Sberry]

The C/B needs to be properly sized to protect the entire length of the feeder (e.g. nail or other failure causing a hard short in wire at some point in the future).

This wire sizing to breaker relationship in this case (short circuit) is number 12 on a 50A. Th nail is not the situation where number 6 is sized to it. Only place that needs a 6 is oven or range, pottery kiln where the load iscontinuouss. The rest of these circuits the breaker is NOT there to protect the wire for thermal, this protection is offered in the form that the attachedd appliance cannot draw enough to overload the wire.

A buzz box is like this, has a number 12 cord, will not overheat any wire connected to it larger than the 12 regardless of the breaker,,,, could have 100, is not going to cook the wire in the wall,, but there are some buts,,,, some of the internals are designed to be connected to limited breakers, circuits above 50 need 10 wire, above 60 to 100 some use 8. This is for the nail scenariorio.

Similar to a fixture wire, the load is limited by the allowable lamp wattage, the 16 wire is not protected by thermal by a 20A breaker but sufficientcient to trip it in the event of a fault.

[NathanH]

The 8 gauge feeding the garage could be a porblem. I understand that it may be sufficent but is surely not ideal. Is the garage attached? How long of a run from the main circuit box to the sub panel in the garage? Heat is the enemy there as is voltage drop. My garage is detached and it was about a 200' run to there. When I installed the 100A subpanel in the garage I ran 1 gauge. I run 6 gauge to all 50A plugs in the garage. Keeps heat and voltage drop to a minimum. I would consider replacing the factory cord on the T-bolt also. Maybe just me, but this seemed to make a differance in performance. Smoother and easier to strike rods.

[MacDuff]

The 8 gauge feeding the garage could be a porblem. How long of a run from the main circuit box to the sub panel in the garage?

The run is about 50 feet from the main panel and the garage is attached. I'll be rewiring the sub panel in the garage with 6AWG. More of a project then I was planning, but better safe than sorry.

[MacDuff]

This wire sizing to breaker relationship in this case (short circuit) is number 12 on a 50A. Th nail is not the situation where number 6 is sized to it.

I'm guessing the "nail" is referring to a rod becoming stuck in place when laying a bead? (dead short?)

Your explanation is very logical and I would tend to agree with all your points. I'm planning to rewire the sub panel with 6AWG and most likely use the 8AWG for my run to the welder. This way I can run lights in the garage instead of only the welder without worrying about tripping the circuit every time I try to use the welder. Thoughts?

[NathanH]

Yes, you have the right idea there. You have to remember that most garages are not wired with the type of equipment us guys use. We end up with more and more equipment and it can be tough when you are welding full bore and say your air compressor kicks on. Sometimes it is best to bite the bullet and do it up with future upgrades in mind. However, I think 6ga feeding your sub panel with a 50a breaker and running 8ga to the welder outlet should be sufficent. Most of the time you will not have the welder cranked up to the max anyway.

[Sberry]

I'm guessing the "nail" is referring to a rod becoming stuck in place when laying a bead? (dead short?)

The "nail" being a dead short on the primary including the internals of the machine if it doesnt have its own thermal. You got a machine with a 12 cord, could plug it in to a 10 wire circuit with 200A breaker, will not overheat the 10 building wire. In a welder circuit the breaker is not there to protect the wire from overheating.

Your explanation is very logical and I would tend to agree with all your points. I'm planning to rewire the sub panel with 6AWG and most likely use the 8AWG for my run to the welder. This way I can run lights in the garage instead of only the welder without worrying about tripping the circuit every time I try to use the welder. Thoughts?

This is good.