220V 50 A with 6-2?

I'm not sure of the internal wiring of the welders you have. Most, I suppose, will actually operate on 220 volts and the third wire will basically be a groundING (bond) conductor as opposed to serving as the groundED (neutral) conductor. However, It's possible that some of them will actually use the third wire to provide for some 115 volt control functions of the welder or for low power operations. I'd think you're going to be safe with the 6/2 with ground. #10 is large enough for the grounding conductor for #6 wire and/or 40 amp breaker.

Conduit is to protect the wire from physical damage. If it is not subject to physical damage or to explosive / corrosive atmospheres, and is not in a commercial or industrial building you're generally all right without it. You *may* wish to check with your local electrical inspector or at least a local electrician but most folks would just install it and be sure all connections are tight so you don't get any arcing.

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stag5353 wrote:

news: snipped-for-privacy@z14g2000cwz.googlegroups.com...

I suggest you hire a qualified electrician before you get yourself in trouble.

Over the last 30 or 40 years, 240 volt welders have been wired up with

1) 2 hots and a neutral 2) 2 hots and a ground, or 3) 2 hots, neutral, and ground. 2 hots and a neutral does not give you a positive case ground so it can potentially hazardous. 2 hots and a ground is safer but the welder is not supposed to have any 110 volt components (like a fan)

Your 6-2 cable is acceptable ONLY for 2 hots and a ground configured machines. If you going to have a general purpose outlet, I would rather see the whole treatment: 2 hots, neutral, ground, and a 4 pin plug.

I'd menti> Hi,

I have a similar set up - 220V 50A breaker, 6/3 Romex, 35' run from the breaker to the plug for my Lincoln 185 TIG. I will need to sometimes get the welder an additional 25' to the front of the shop for work and ventilation in stick mode. Would a 25' extension cord make the total run too long? If it is possible, what size extension cord would you recommend.

TIA, Mike H.

Check your local codes and the NEC. A #10 is sufficient for a ground lead on a 50a circuit unless local codes are more restrictive. It had BETTER not be a current-carrying conductor :)

Romex should never be run inside of conduit. Personally, I would not run anything BUT Romex without a conduit, but again, check your local codes... THHN may be allowed. Some codes still allow BX (armored cable), but it is no longer legal for residential in my area.

I'm not sure about the legality of Romex running exposed in a shop/garage situation. I've done it, but I don't know if it's legal.

Ampacity of any conductor will be reduced depending on the fill percentage of the conduit... you can pass less current through a pair of #6 in a 1" conduit than you can in a 2" conduit, and if you manage to stuff four #6's into a 1", it will be good for even less (no, I don't think four #6 is legal for a 1" pipe). This is all due to heat buildup.

Ignore the guys at Home Depot. Check your local codes. If you are doing any work, it must meet or exceed those local codes. If it is a job requiring a permit, worst case is when you sell the home, you'll have to pay a small fine (usually double the cost of the permit), but at least you won't have to rip it out and/or rewire it.

If in doubt, exceed code.

--- Rich

you're

Thanks for the sound advice... the welders I have (Millermatic 210 and a 180SD) are set up to accept a ground and two hots. Could you elaborate on the differences between a goundING (bond) conductor and a groundED (neutral) conductor and how these 220V circuits work... if only a ground is used, where does the current go? I am an electromechanical designer and have a solid background in DC electronics, but my AC needs some brushing up (haven't dealt with it a lot since college).

sufficient.

appreciated.

Thanks for the concern... I plan on having an electrician come in to check my work before I flip the switch.

What is the actual maximum amperage and what is the operating range of the welder? It's all about voltage drop and how much you can tolerate. I check the local scrap yard frequently, just grabbed some 6/4 cord at a scrap price, which wasn't exactly cheap but way less than new.

A groundING conductor is simply a safety ground designed to ensure that the metallic case remains at ground potential should an internal short or other problem feed line voltage to the chassis.

A groundED conductor is a return path for 110vac.

You have three lines coming into your home. Two are hot, one is grounded. If you measure the potential across the two that are hot, you'll read 220-240. If you measure each one to ground, you'll read

110-120. The two hot lines are 180 degrees out of phase, so when used together they are additive in nature (voltage wise) and provide 220-240.

Depending on installation design, the groundED conductor may or may not be tied to the ground rod at the service, and hence, the groundING conductor. Most traffic signal installations ground the neutral at the service in addition to providing a secondary ground rod in the cabinet AND full bonding of all conduits at each signal pole.

--- Rich

It would be good to get his input before you do the wiring so you don't have to redo anything. For one thing, 6 gauge copper wire may or may not be big enough for a 50 A circuit. Table 310-16 in the NEC lists 6 gauge with appropriate insulation as having 55 A ampacity, when used with breakers or other terminals with 60 degree C rating, at 86 degree F ambient temperature. If the ambient temperature where the wire installed exceeds this, the ampacity is less. For instance, where I live it gets well over 100 degrees F, and the ampacity would be 39 A. You couldn't legally use a breaker over

40A with it. OTOH unless you are in a _really_ hot part of the country, you could probably get by with 4 gauge.

BTW The NEC is not law in all jurisdictions. But it is used in some form by most. And even where it is not part of some local code, it represents good practice.

It is starting to become overkill.

I'm getting wind of the '05 or '06 codes requiring GFCI on *ALL* interior residential receptacles. Grounding/bonding requirements have tightened as well.

--- Rich

I'm surprised to hear that #6 might not be sufficient... Miller calls out #8 as minimum conductor size for a 45' run. The manufacturer of the cable rates it at 60 amps... the manufacturer of the outlet (Pass and Seymour) suggests #10 to #6... and I've heard from plenty of others that say it is more than sufficient for a 40 amp circuit. Interesting to hear how much the temp affects ampacity though. What is the equation for this?

Footy wrote:

breakers or

temperature.

breaker over

country, you

represents good

Big question to those reading this...for most welders like this...60 amps is balls to the wall 200-250 amps at the stinger. How many of us ever use that much juice except for the very very rare exception?

if you are burning the usual 1/8" rod...you are down about half that in amperage at the wall outlet.

Gunner

Rule #35 "That which does not kill you, has made a huge tactical error"

Different insulations give different ratings for wire, but the LOWEST rating I've heard of for #6 COPPER wire is 60 or 65 amps. Aluminum would be down just a bit, but would be good for at least 50 amps.

I'm aware of a DErating of only 80% of that for CONTINUOUS use (on 3 hours straight) but this would not apply for any welder (man or machine) that I'm aware of. Some machines have duty cycles of 15 or 20 percent but if they were ALL 100% it takes time to set up for a weld. NO ONE that I'm aware of is going to weld 3 hours straight without some kind of break, even with a mig machine.

Generators have a continuous rating and a surge rating. Wires are fairly similar. A #6 copper conductor could probably take 100 amps for very short bursts with very little, if any, damage to the wire. Many breakers likewise can take currents far above their ratings for very short bursts, as can slow-blow type fuses. The old "knob and tube" wiring system (? pre 1950's house wiring) or what's known today as "conductor in free air" as in individual wires strung on insulators like the power companies use on the poles would easily allow #6 copper to be rated at around 100 amps.

The breaker is to protect the wire - from overheating. The insulation is also to protect the wire - from short circuits. The "temp" can refer to ambient, especially in a conduit, as in a high ceiling or in a boiler room. The temperature rating of the insulation basically says the wire can heat up to 60, 75, 90 or higher degrees CENTIGRADE without harm to the insulation.

I have a new NEC (National Electrical Code) for 2005 (they come out every 3 yrs) but loaned it to a friend to do some "continuing education" tests to maintain his license so it is not handy at this moment. He's retired as am I.

With a 40 amp breaker the wire is WAY OVER PROTECTED even with a 60 degree C rating. I'd say throw it in and get to work. ;-) If you have a machine that occasionally trips the breaker you can go to a 50 or 60 amp breaker. (Wish I knew the ASCII (? sp) code to produce the degree symbol.)

I don't know of a "formula" or "equation" for the temp / ampacity relationship. It is based on the construction or formula used in the manufacture of the insulation which is provide to the NFPA (? National Fire Prevention Association) or determined by them. They then print it in tables in the NEC and the electrician just looks it up.

Hope this helps. If you have ANY problem at all it'll probably be in not notifying the code "authorities" so they can get a commission for coming out and examining everything - and possibly raising your property taxes to be sure you're taxed AGAIN, annually, on all your equipment. The ONE CAVEAT might be to be sure your homeowner's insurance is going to pay off if someone gets hurt or the property burns in case you're doing this in a residential situation. IF the insurance company doesn't insure it you could jeopardize your mortgage which could jeopardize your home! Ain't it good to be FREE? :-)

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stag5353 wrote:

I *think* this is the first year the NEC has had a subtitle to indicate it is not only a national standard but is also an INTERNATIONAL standard. As mentioned in another message, I don't have my copy handy so I can give you the correct wording.

PAUSE . . . I went to

and did a search for NEC to see if their catalog would show the exact wording. You can see on the NEC 2005 picture that it has a two line subheading, but it's not clear enough to read it and is not in PDF format so one can enlarge it enough to read.

OK. Good old Amazon.com provided the answer. A blowup of their ad provides:

NEC 2005 (first line) NFPA 70 National Electrical Code (second line) International Electrical Code Series (third line)

That third line is something new!

While it is "not law" officially in all areas it is often specified in laws and/or specifications for construction that it comply with the NEC and/or "all applicable codes" which is just a way of shifting responsibility and CYA. Perhaps that last would be CTA - Covering THEIR XXX.

GENERALLY, if you do it "by the book" you have nothing to worry about. However, even in any one state you'll find differences of soil types for example which could require that some conduits be coated with a rubber or plastic coating, as in chemical plants, to protect the conduit from chemicals in the soil. You'll also find that some counties, boroughs, burgs, cities, towns, etc., usually rural and often because of finances don't have "enforcing authorities" who are quite as demanding as other areas. Areas near the ocean could have fairly salty soils and/or air which could prevent the use of certain types of conduits, ground rods, fittings, etc. or require a protective coating.

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Rich Lockyer wrote:

In AC wiring you always have a groundING conductor for safety. This conductor bonds the frame of the welder, in this case, to earth. If a failure in the welder connects one of the hot wires to the frame the groundING conductor will draw the current back to the service entrance, and pop the breaker. In this way you should never have a tool with 120 volts on the frame even if there is an internal failure. The groundED conductor (neutral) caries current in normal operation. If it is broken on its way back to the service entrance the tool will not work, but because it is not connected to the frame of the tool no harm is done. If you try and save money by using the safety ground wire as a neutral the welder will work, but a single failed connection in the neutral will place fatal voltage on the welders frame.

Mike

Normally you just use the appropriate table, 310-16 in this case, where most of the calculations have already been done for you. There is a formula that can be used under engineering supervision in lieu of the tables. It is in section 310-15 of the version of the NEC I have. It is:

I = sqrt(((TC-(TA + DELTA TD))/(RDC (1 + YC) RCA))

where TC = conductor temperature, TA = ambient temperature, DELTA TD = dielectric loss temperature rise, RDC = DC resistance of the conductor at conductor temperature, YC = component ac resistance resulting from skin effect and proximity effect, and RCA = effective thermal resistance between conductor and surrounding environment.

Using the formula can sometimes result in greater ampacity, and therefore the ability to get by with smaller conductors, than using the table.