Wiring up the plasma cutter

[Chris_L]

my miller 375 has the option of running off 110 or 220. I opted for the higher voltage. I tapped into the female end of my welding cord and ran another 15' or so cord from that.
I did have to turn one of the prongs on the plasma plug to mate up to the female 220 plug

Female 220 end

Dual welding/plasma cord

[HIGLET]

Chris are you sure that female end is rated high enough for the cutter? Usually those are only 20ampers

[Dukes69]

Chris are you sure that female end is rated high enough for the cutter? Usually those are only 20ampers

I was actually wondering the same thing. I know my Thermal Dynamics cutter manual says to cut off the stock plug when using it for 220v.

:confused:

[Chris_L]

Hmmm....I am not sure. The cutter maxes at 27 amps. The cord is a #8 same as the welding cord. Mr.Blaine is the one who told me how to do it. It works fine with out issue. I will skim through the manual and check [use manual as last resort] :confused:

[HIGLET]

the cord with the plug is #8?

I believe it could be 8/3SJO which means 3 8ga wires iside the jacket. Which is more than enough for that amperage. My concern would be the plug itself melting at the screw that holds the bare wire. I have had many many cords melt at that point. The screw gets hotter than the plastic is rated for. ALL THAT SAID plasma cutters don't really have the same length of use, constant amperage draw as the lights I've destroyed equipment with do.

I just don't want anything to happen to your house fire wise

[NAILER341]

if it were me.... i'd just buyt the right plug at home depot for 10 bucks, and get on with my day without a worry
you already have so much invested in this thing, there is no point skimping on a plug at this point
just another opinion :yay:

[Chris_L]

Thanks for the tips guys. I don't know a whole lot when it comes to electrical work, aside from the few times I've stuck my trowel to close to an outlet while plastering....then there was the time I was installing a high end french stove that was wired to 220 and the air guys left the curcuit on and I grounded out between the two. I had to sit down for quite a while and my arm was an interesting color of red.

I will go check out some heavier duty plugs and re-do it

[goodtimes]

All you have to do is see what the plug is rated for (should be stamped on it somewhere). From the looks of it, the receptical (the yellow one in your hand in the above pic) is a NEMA 5-20R. If so, it is only rated for 125volts, and 20 amps. The plug on the plazma cutter, appears to be a NEMA 6-30p (250 volt, 30 amp)...but that is (visually) close to a 5-20P (125/20amp). I am willing to bet that they are either both 6-30's, or both 5-20's. A 6-30 plug will not mate up with a 5-20 receptical.

The key things to check for are the 250 volts, and the 30 amps. You can use whatever plug configuration you want, as long as they are rated for a minimum of 250 and 30. Personally, I use L6-30's (2 pole, 3 wire, 250 volt, 30 amp twist-locks)...but that is just because that is what I used to have in the shop at TRW....so that is what I put on my tools when they were used there....so I just kept 'em and wired the garage accordingly.

Remember, 250v/30a!!!! And with that configuration pictured above, you do not, under any circumstances, want to run both the welder and plazma cutter at the same time. You will have a fire on your hands (or in your cord). Also be sure your breaker is sized accordingly! Rule of thumb....size the wire/plugs/recpticals/etc. to the load, and then size your breaker to the wiring. That is, your wiring needs to handle more watts (amps x volts) than your breaker will allow, and more than your load should draw.

And of course, just to be technical, you really shouldn't be using a breaker for your plazma cutter. You should be using a fused disconnect with slow-blow fuses. Plazma cutters have a huge in-rush current, then it drops off very rapidly. This surge will trip the circuit breaker if it is sized too small. The downside to sizing the breaker big enough to handle the inrush current, is that you lose your protection once the inrush drops off. That said, I run both my millermatic 220 and hypertherm 380 off of a dedicated 30 amp circuit (protected by a breaker)....just like 99% of plazma cutter owners.

And keep in mind, any wiring that is done to the house (new recepticals, etc) must be inspected by a county or state electrical inspector. If it isn't, and something goes wrong, your home owners insurance will most likely not pay for the damages caused by such wiring. Most people ignore this, and never have a problem. But please be aware of the possibilities if something bad happens.

[Chris_L]

Thanks for the info goodtimes. I run the power from the existing 220 dryer outlet in my garage which I believe is a 30 amp seperate line. I always use one thing at a time and never have the welder and cutter on at the same time. I will still check on getting a better plug for the female end.