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Thread: Wiring Angst

  1. #1
    Join Date
    Dec 2007
    Posts
    7

    Default Wiring Angst

    Hi, first post here & I would really appreciate some input from any electrical experts.

    We gave our son an MM180 for Christmas and later learned that the 220 outlet in his studio (he's a sculptor) is not live. The building is totally rewired--except for that circuit.

    The MM180 specs are:

    Input Power
    230 V, 21.7 A, 60 Hz
    Rated Output
    135 A at 22.5 VDC, 30% Duty Cycle
    Welding Amperage Range
    30 - 180 Amps

    In reading here and on other forums, I think I have two options.

    1. extend a 220 circuit that is almost never used another 100 feet to his studio. This is a 4-wire, 120/240-volt circuit, so if I understand correctly, I would have to cap the neutral on either end and make sure the ground is connected correctly. this circuit is fed by a double 30-amp breaker, 10-gauge wire, and is currently about 60 feet long. I would be adding 90 to 100 feet of 10 gauge to it. Does all this sound right? Can I use the two hots coming from the double 30-amp breaker?
    2. run a totally new, dedicated circuit of 10-2 plus ground, in conduit, about 150 feet from panel to receptacle. If I do this, there are only two empty slots in the breaker panel and they are opposite to one another. would I take the hot wires off of two single, 30-amp breakers in this case?


    I've done a fair amount of 110-v wiring in my time; not that much 220. I just want this to be safe and done right.

    Thanks!

    angus

  2. #2
    Join Date
    Oct 2007
    Location
    Tennessee this week, Wyoming next week.
    Posts
    49

    Default

    Option #1 sounds like the most effective and the cheapest.
    Is there any chance of determining why the 220 outlet in the studio is not energized? It might just be a matter of locating the other end of the wiring at the panel and adding a breaker to that exisitng wiring. Run that down first.

    Don't let 220 scare you. It's only 110 twice. On a 220 circuit the neutral is used by any 110v appliances on that circuit - like the timers and blinking lights on a fancy dryer.. Most applications like your son's welder use only two hots and a ground. If there is a neutral (white) wire in addition to a black and a red, it is just ignored. If there is no red wire, the white is used as the second hot - but should be marked as such. (Browse around the electrical dept at the local home improvement center and you'll find electrical tape in colors other than black - that's what they are for; marking wires to indicate their function).

  3. #3
    Join Date
    Dec 2007
    Posts
    7

    Default

    Thanks for the reply, AnotherDano.

    Sorry, I should have mentioned that all that's left of the "circuit" in his studio is the conduit, but I can use it for the extension I described in option 1.

    Just to be sure: for option 1 (converting an unused 4-wire circuit to 3-wire and extending it), you're saying I can get the 2 hot wires i need for the welder from the red and black wires on the 4-wire coming from the two-pole 30-amp breaker? Then I'd just disconnect the white at the panel, tape it off and make sure the ground is actually grounded?

    Thanks again!

    angus

  4. #4
    Join Date
    Jun 2006
    Location
    Killingworth,Ct.
    Posts
    372

    Default Im Lost

    re you saying there emt runnig to the 220 circut,but no wires in there????or as dano said,if its wired,it has to go some place,You could get luky,not knowing the building,but the old ones the spruce up for rental space,the thing could be wired,and the breaker shut off,They usually run a couple of sub panels in the rehabs ive seen!!!!!Good Luck,and Let us know!,Jack

  5. #5
    Join Date
    Nov 2007
    Location
    West Georgia
    Posts
    103

    Default 2 questions

    As an interested amateur, I'm wondering 2 things.

    1) Why is there no sub-panel in the studio?
    2) Is a run of 160 feet so long that larger wire is needed to offset current loss?

  6. #6
    Join Date
    Dec 2007
    Posts
    7

    Default

    storts, it's definitely empty conduit running only part way out of the studio. But I can definitely use that conduit for the new circuit.

    I had another thought, if anyone's not already burned out on this. Sorry to have so many questions, but I don't want to overlook the best solution.

    If I wanted to keep that existing, seldom-used 120/240 circuit live and untouched (it's for a floor polisher), could I do this?
    1. Leave the 4-wire circuit running from the breaker panel to its receptacle as-is.
    2. Just tap the two hots and ground on the 4-wire at the junction box and run 2 hots and a ground from the junction box on to the studio


    In this scenario, the neutral on the 4-wire would be untouched--still connected at the panel and receptacle--but would not be part of the 3-wire circuit.

    The owner of the building would prefer to have continued access to that original 4-wire circuit, if possible, but might actually use it once or twice a year and NEVER while my son is using his welder.

    This would be by far the easiest and cheapest if it's safe and up to code.

    Thank very much.

    angus

  7. #7
    Join Date
    Oct 2007
    Location
    Tennessee this week, Wyoming next week.
    Posts
    49

    Default

    I don't see a problem with that. If you like your landlord, you could run all four wires through the conduit and just use three, leaving him the option of having the neurtal for some later purpose. The difference would be the cost of another wire and the additional labor to pull it. It's much cheaper on the labor to do it now. The neutral wire would just be capped off at the studio outlet, but wired through the 'buffer' outlet.

    Otherwise, pull a black, red and ground through the conduit and make your connections, ignoring the neutral at the 'buffer' outlet.

    Curious... In that 'buffer' outlet, what color wires are present?

  8. #8
    Join Date
    Jun 2006
    Location
    Killingworth,Ct.
    Posts
    372

    Default No Worrys

    Thats what these forums are here for,one helping others,,As dano said,you would be a hero in your land lords eyes,as the price of copper,and your helping him out also,and it would be the quickest,Hanging the conduit takes time,and a pain,again as Dano said,no sub panels,seem kind of srtange???But were not there!

    I would do your option 1 cheapest,easyiest,,,My 2 cents!

    I would ask the land lord,if when he bought the building,did they Unwire a 220 wall recpt???????????Just a thought!!
    Last edited by storts; 12-30-2007 at 08:39 AM. Reason: spelling

  9. #9
    Join Date
    Dec 2007
    Posts
    5

    Post

    If my memory serves me, a run of 160 feet that would handle 20+ amps would require 6AWG wire. And it would be improper to add the larger size wire onto a circuit that is already lesser in size.
    I don't know if your son will be using the welder to full capacity, but for code/saftey reasons, you may want to install proper sized wire from the braker out.
    I'll try and find my charts, and copy some more info for you in a little bit.

  10. #10
    Join Date
    Dec 2007
    Posts
    7

    Default

    The calculators I've seen let you go up to 140 feet with 10-2, and our longest run turned out to be around 130 feet. Also, he'll almost never use the welder at full capacity.

    In any event, my son & I worked about 10 hours yesterday and ran a total of about 140 feet of emt and 10-2 wire to power two new 240-v receptacles for his welder. It was tough going--working on a scissors lift on 18-foot ceilings--but a great project for us to work together on. Tested across all the hot legs/grounds at the two receptacles we installed and the 1 previously existing receptacle and all are right a 124 volts per leg. (I did not test across both hot wires since I wasn't sure I could do that and didn't have internet service so I could check here for advice on. Learned this morning that doing so should yield 220 to 240 volts.) So we finished up about 10 p.m., powered up the welder for a minute and then shut off the breaker until the electrician can double check our work.

    Thank very much to everyone for the expert advice. I really appreciate the help.

    Happy New Year.

    angus

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