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#143277 - 01/06/05 02:38 PM 230v 50 amp 4 wire to 230v 30 amp 3 wire
chester Offline
first timer

Registered: 01/06/05
Posts: 2
I recently purchased a home that has a 230v, 50 amp range, 4 wire receptacle in the garage. I have bought a welder that needs 230v, 30 amp 3 wire connection. Welder does not have a plug yet. There are 3 wires, a black hot, a red hot, and a multi-colored whiteand green nuetral/ground. I would like to make an extention cord about 100'+ to weld away from the garage. What are my best options? I know with extention cords you lose amerage. I already have a 50' run from the box to receptacle with 50 amp line. Can I just connect my 3 wire welder to a 4 wire plug? If so, how? (especiallly interested in how to connect the ground/neutral wire from the welder.) Should I change out the breaker from 50 amp to 30 amp and re-wire receptacle? Can it sustain the length of runs I'm trying to accomplish?
50' run from braker to receptacle is 6/3/w ground. New Christmas welder but can't use until I'm clear about how to hook up safely. Any help would be greatly appreciated. I'm not an electrician, but a pretty capable handyman.

THX
Chester

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#143278 - 01/07/05 08:45 AM Re: 230v 50 amp 4 wire to 230v 30 amp 3 wire
3phase Offline
Carpal Tunnel

Registered: 09/09/02
Posts: 6849
Loc: Licensed Electrical Contractor...
I wouldn't recommend using a welder on an extension cord. It would be possible to use the #6 with a 30A breaker. The recpt would need to be changed to a 30A one. It might cause confusion for later owners seeing a 30A recpt on # 6 wire though. Welder normally uses 2 hots and ground to recpt.
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#143279 - 01/07/05 03:03 PM Re: 230v 50 amp 4 wire to 230v 30 amp 3 wire
monocline Offline
Handyman

Registered: 02/06/03
Posts: 656
Chester,

I am not an electrician, but maybe my comments can help you find answers to all of your questions.

Some welder manufacturer's instructions are very clear in specifying the breaker size, the wire size and length and extension cord size and length. If you welder’s instructions are not that specific you can use the nameplate info to size the circuit. You need to know the primary (or input) current and the duty cycle for the rated output. The rules for welder circuits are different than those for general purpose branch circuits.

I don’t know of any welders that use a neutral, just hot, hot and ground. So to use this 6/3 with ground you would cap the neutral at both ends and use the two hots and the ground with a 3 wire receptacle. The breaker and receptacle size depends on the welder.

You can use an extension cord with your welder, it just needs to be the proper size and type. Type "SJ" (Service Junior) is rated at 300 volts and has a thinner jacket than type "S" (Service) cords which are rated at 600 volts. If used outdoors it must also have a "W" (Wet location) in the description. Type SJ cords are lighter and more flexible than type S cords but are not recommended for heavy use or abrasive environments. A "T" in the cord type designates a Thermoplastic insulation and jacket, which would be stiffer and harder to work with than rubber. Types SOOW and SJOOW use a rubber insulation and jacket. The cord plug and receptacle you choose depends on the welder’s requirements. Also, be aware that the nomenclature is not consistent when referring to cable, such as Romex, and cords. It common to refer to 3 wire with ground Romex as a 3 wire cable (even though there are 4 wires in it), where a 3 wire cord is just that, a cord with 3 insulated wires.

You do not “lose amperage” with extension cords, but there will be a drop in voltage as the length of the circuit increases. So, unless you plan on doing all of your welding 100’ from the garage you may want cords of different lengths. I’ve heard it recommended that if you have a long cord to uncoil all of it when using it, something to do with induction, phase shifts and arc characteristics.


If your instructions aren’t much help, give us the model and specs of your welder and we will go from there.

Bryan

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Horses don't dance.

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#143280 - 01/07/05 05:07 PM Re: 230v 50 amp 4 wire to 230v 30 amp 3 wire
chester Offline
first timer

Registered: 01/06/05
Posts: 2
Thanks so much for you advice. Welder is a "Clarke Weld Mig 180EN" 230V. I bought it on recommendation of a friend that has used one for years without any problems. You advice to cap the neutral at both ends is logical (I just didn't think of it). Most welding will be done away from power source. Therefore, my concern about losing volts. Is there a concern about hooking a 30 amp draw unit into a receptacle with 50 amps available? The welder unit is supposed to have auto shut down to protect itself.


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#143281 - 01/08/05 08:20 AM Re: 230v 50 amp 4 wire to 230v 30 amp 3 wire
MikeEG Offline
journeyman

Registered: 04/01/04
Posts: 86
In reply to:

Is there a concern about hooking a 30 amp draw unit into a receptacle with 50 amps available?




Yes, there is. See this recent thread: http://www.handymanwire.com/ubbthreads/showflat.php?Cat=&Board=UBB2&Number=363977&page=2&view=collapsed&sb=5&o=&fpart=1

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#143282 - 01/08/05 09:36 AM Re: 230v 50 amp 4 wire to 230v 30 amp 3 wire
monocline Offline
Handyman

Registered: 02/06/03
Posts: 656
The rules for welders are different. The breaker serving a welder circuit can up to twice the welder’s primary input amperage rating. A typical 180 amp MIG would draw 20 to 25 amps for the 180 amp output.

A 50 amp breaker is likely right at or over the limit.

If, the instructions do not specify the breaker size to use, then, we need to know the welder’s input amperage (for the rated output) in order to size the breaker. This can be found on the nameplate or in the manual.


It would be ok to use a 30 amp breaker and receptacle with this existing 6/2 cable, voltage drop for this 50’ circuit would not be a concern as the 6 AWG conductors are much larger than this welder would require.


The voltage drop for 125’ of extension cord could be significant. If your source voltage is at, or near, 240 volts then 10 AWG should be ok (a 25 amp draw would result in a drop of 7.8 volts). Since this welder’s rated input voltage is 220 volts there may be some leeway.

An 8 or 10 AWG extension cord with a 30 amp plug and receptacle, plugged into a 30 amp receptacle protected by a 30 amp breaker should be fine.

I’ not qualified to give advice in this matter, so confirm everything I mentioned.

Bryan

_________________________
Horses don't dance.

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