Power Hook up for welder and air compressor.

Ok guy's I want to hook up power for my 230 welders and my 230 air compressor.
In my main power box I only have a place for 2 breakers then it will be full.
I want to run some wire from the two new breakers outside to a seperate little
breaker box then run two seperate wires out from there to 2 - 230 plugs.
What size breakers should I run, out from the main breaker to the small breaker box.
Then what size breakers should I run for each plug? {50} times two for one plug???
I forgot I am just going thru the wall and over about 5 or 6 feet.
I have some wire that I had from florida when I ran a 200ft. run for my welders,
so it's some healthy stuff about as thick as my wrist.
Thanks Kurt

Kurt, it looks like we have no electrician types on here. :) I'd try to help you, but I'd probably burn your shop down. :eek:

Don

Kurt, you need first to figure the total amps you expect to run if both the compressor and the welder are running at the same time. Say, for example, the compressor requires a 30 amp two pole breaker (240volt), and the welder needs a 40 amp; you will need to get one 70 amp two pole breaker for the main panel, then in the small panel outside, put in a 30A 2 pole, and a 40A 2 pole, and wire the plugs from them. Wire size for that run from the main panel to the sub-panel should be #4 stranded copper, and the 30A circuit would require #10, and the 40, #8. Use stranded for all of it, and size your ground run the same as the current carrying conductors. Feel like you might want a coach, PM me; I might like a field trip.

Rrumbler is right on... On the outside box I would install an earth ground get a copper rod or copper clad rod at least 6' long drive it into the ground below the box and run a ground wire back up to the box and tie it in with the ground wire from the panel. There should be a small knock out on the bottom of your outside box to run the wire thru.

I would add that before you add that 70A breaker to your existing panel you need to look at the amp rating on that panel and see what you're already running with your existing circuits. Unless the house was custom and the owner specified the service you may only have a single 100A service (or less) into the dwelling, and you would not want to sub-feed 70 amps out to another box if that's the case. You may need to run another service into the house for your increased 240V loads. Just because you have a breaker space remaining does not mean you have feeder capacity for your new load.

Yep Roger is spot on. When We added the addition, we had to put a way bigger main box in and we ran a sub panel to the rebuilt chicken shed/aka garage. At the time I wanted 220v out there, but it would of meant another larger upgrade and P G and E coming out to disconnect and reconnect, so I settled for 110, and a smaller amount of juice in the garage. Everything was done in stages, and our initial electrician, had moved out of town, so the new guy didn't know I wanted 220 until, after the new box was put in(we connected the garage a year after the addition, even though we built it a year before! By then Gary had moved back to town, and the interim electrician, had quit the trade to go into the hearing aid buisness. But the point here is you may need a bigger service panel and connection to the main pole.

This is so true... I have 200 amp in the house and a 60 amp pony on that. Nothing is ever overloaded so when I put up the new garage I wanted 220 there too so I put in a new 220 panel and meter. the electric co. didn't like the idea until I put the new building in the bussines name. Then all was good.

my back up power was done a slightly different way.
an electrical buddy was having his car rebuilt in my shop, he is next to hopeless working on a car, but a genius for pulling wire.
i have a 6500 watt genset that puts out 24 amps so thats where my buddy started.
he brought over some teckie test equipment to see what the needed appliances pulled for amps when they started up.
his goal was to not exceed 20 amps.
in very short order he came up with a list of what i could power up with the generator
220 volt deep water pump, the fridge, the furnace, 6 60 watt lights, and a large coffee maker!
he put in a small sub panel in the house with all the needed stuff in it, then ran some heavy guage wiring , i believe he called it cab tar? outside in has a odd plug in (4) prong that locks into the genset. at the other end where the sub panel is he used the same wire. heres the neat part...the sub panel unplugs from the main panel
with the the same twist lock plug then the genset plugs into the sub panel! he made sure that by wiring the sub panels female plug that the power supply could not be plugged into the main panel. works very well no issues.
as an added precaution he also made me purchase a couple of good quality surge protectors, in case of power surges\drops lightning, put those on the well,fridge &
computer(45.00 bucks a piece but well worth it!)
have used this system quite a few times,being out in the country, even the wife can switch over to back up power,:)

Thanks Cffisher; I did the same thing with the grounding rods in my Florida home.
The last owners of this home had a jaccuzzi hooked up that was 220 but is no longer out there.
They have a sepprate 100 amp box on the other side of the house for it.
That is tied in to the main but I am not using it, because it is to far away from where the compressor will be.
The compressor has a on and off switch on the side that I only turn on when I am using it.
So the Compressor and Welders will never be going at the same time anyway.
It's just a pain pluggin and unpluggin everything when ever you want to use something.
This is just gonna be on the outside of my house in the back yard till I get a new shop built.
Then I'll have the power company run me a new line in when thats done.
Thanks Rrumbler; I talked to a electrician today and he said everything I got is good,
I just have to get some really big wire to go to the new power box.
The wire I already have is good from the box to the plugs though.
This set up here is differant from the set up I had in Florida.
The first thing is there is a big main breaker box out side the house then a big breaker box inside the house.
In Florida I had one main breaker box out side the house.
The big power 220 stuff were all three wire hook up and here the big 220 stuff is four wire hook up.
I other words they have both a ground and a neutral wire along with two power wires.
Kurt

Kurt, four wire installations are common for things like stoves, dryers, and jacuzzis because the have both 220 and 110 devices in them. For your compressor and welder, look at the plug; if it only has three blades on it, it only needs the two hot legs and the ground, no neutral. You can run a neutral, but you would just leave it capped off and stuffed in the back of the box, not connected to the receptacle. Save the wire, it's probably not necessary. Now, if you want to plan for future 110 load out there, or even provide for it now, run the four wire to the sub-panel, and then just the three wire legs for the welder and compressor from there. And, you can install a ground rod, but in the desert, it is pretty ineffective, and not called for in the electrical code for the type of install you're doing; again, save the money, and the work - putting down an eight foot ground rod in this ground is usually an exercise in frustration at the least, and futility at worst. That contiuous ground wire between devices and panels is a far better safety means. Yep, I am a "sparky", "wire bender", "lightning wrangler", and other sorts of names for electricians; been retired for a good while, but like my sig. says: "Not entirely dead - yet". The offer still stands.

Hey Thanks Rrumbler;
Ya both my welders and my compressor have 3 wires, I wired them when I got them.
Both my dryer and my stove in Florida had three wires as well.
When I got here the outlet in the walls for the stove and the dryer were both 4 prong.
So I went to home depot to get some new cords and the guy said to just change
the outlets them selves because it was cheaper then buying new cords.
I used the ground to ground out the box then used the neutral and two power
wires to hook it up.
So thats what I did and saved about $20 bucks.
So anyway all my 220 stuff will be 3 prong now.
Kurt