Help setting up my new tig

By beefalobilly Date 02-28-2006 23:59

So I've got a new miller syncrowave 180 SD, and I'm going to be installing it, but I've got a few questions, (because I know next to nothing about house wiring.) We've got a hot tub there, so I'm trying to figure out a way to use it's existing wiring to minimize work and cost! Here's a drawing to help illustrate my dillema. http://webpages.charter.net/trevor_lee/welder.GIF
The blue line is how I would like to wire it (if possible).

First, the manual says that the max reccomended size breaker is 100 amps. We've already got a 50 amp fuse in the breaker box, but it says the input amps are 67, so I'd need at least a 70 or so shouldn't I? Now, problem is that this breaker leads to our hot tub, but it leads to another 50 amp breaker right next to the hot tub. (see the illustration.) Couldn't I get away with putting in the larger breaker in the main box, since there's still a 50 right next to the hot tub?

Second, I think I got lucky in that the cable wiring the hot tub is 8 AWG, (which is the minimum input size). Is there a way I can splice into that cable (I really don't want to run an entirely new line, it's pretty far from the main breaker box to the welder, and that AWG 8 is expensive.) and run it to the welder? The blue line is what I'd like to run (as long as it's possible.) Keep in mind, that I'd never have the hot tub and welder running at the same time!

Third, just to make sure, the cable is made like this, it's got a black sheeth with three conductors, white black and red, plus a ground. On the outside black sheeth it says "romex CR1 awg 8 cu 3 cdr with awg 10 ground." Is the AWG 10 ground large enough?

Thanks for the help everyone... Hopefully this makes sense!

By billvanderhoof (****)

Date 03-02-2006 07:24

First the disclaimer, I am not an electrician so don't take any of this as gospel.

The code probably requires the hot tub to be on a dedicated circuit, thus any branch in that cuircuit would not be allowed.

Number 8 wire (1 to 3 conductors in a cable or raceway) is only good for 50 amps, unless the wire is high temperature rated. Thus you can't increase the breaker size.

If the wire was large enough to carry the load you could get around the dedicated circuit requirement by installing another breaker box where the line needs to branch. There is a name for this but I don't remember it. Then both the hot tub and the welder would be served by a dedicated breaker. Unfortunately the cost of the parts to do this would probably exceed the cost of the extra wire.

Bottom line- run the wire from a new breaker in the breaker box to the welder, the tables I can find say you will need #6 copper wire for 65 amps. You would seldom ever draw the full 67 amps and even then only intermittantly. Probably not enough overload to open the breaker.

The folks at the electrical supply house can provide helpful advice and may save you money over my recommendations. Perhaps an electrician is a good idea.

Bill

By beefalobilly Date 03-02-2006 17:04

Alright, thanks for the help, I appreciate it!