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460 VAC 3 phase 20-30 amp extension cord

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  • 460 VAC 3 phase 20-30 amp extension cord

    Was thinking of making a 460v extension cord of 50 feet. Anybody done this? I can't seem to find any suitable plugs and receptacles. if 460 3phase is available you can use #14 wire for extension cords making long ones very light and compact.

  • #2
    The national electric code Table 400.5a says #10 for 25A, #8 for 35A, col. A for 3 current carrying conductors in flexable cords (most likely type SO). As for cord caps and recepticals any electrical warehouse or Graingers. They have to be matched to the voltage and ampeage being used. TJ

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    • #3
      Originally posted by TJsparks
      The national electric code Table 400.5a says #10 for 25A, #8 for 35A, col. A for 3 current carrying conductors in flexable cords (most likely type SO). As for cord caps and recepticals any electrical warehouse or Graingers. They have to be matched to the voltage and ampeage being used. TJ
      Thanks TJ. I got my info from my owners manual for my Dynasty 200DX, section 4-11. Calls for #14/4 at 460 volts 3 phase up to 400 feet. I thought that would make a pretty handy and light weight cord. Of course 50 feet would be more than ample for me. The manual also recomends #10 for single phase 110V 30amp less than fifty feet, #12 for 230V.
      I'm with you, I should go by the code first manual second.
      see below, wonder if Miller screwed up?

      http://www.millerwelds.com/om/o2240m_mil.pdf

      Comment


      • #4
        Overkill is good, to a point.

        I use a Millermatic 200 that is hooked up for 230V 1 Phase that is equipped with an 8/3 cable 50 feet long with a 30A 230V 1 Phase dryer plug for connection. I have never had a problem with it at all. My dad purchased this unit this way in the early 80's, usually they have a 10 foot cord instead.

        460V 3 Phase is a different matter. I only know of one house that has 460V 3 Phase power to it, for Air Conditioning and Waterwell use. Most households don't have 460V electricity to them, 230V 4 Wire 3 Phase is more likely since 120V and 240V 1 Phase can be pulled off the lower voltage legs.

        Yes, by the NEC table, and the table in the Miller Manual for for welder, you could use #14 AWG for the 50 foot cord. However, it can't be just any #14 AWG cord. We use what is called SDT cable for power feeds on waterwells. This is a 3 conductor 75 Deg C THHN Standed cable inside a sunlight resistant/direct burial PVC jacket. It is also available in 4 conductor. For your application, #12/3 would cover 230V/460V 3 Phase power options for the 50 foot distance. For 230V 1 Phase you may need #10 or #8, the #8 would be better, and then for 115V 1 Phase, #6. All copper conductors of course. The stranded wire makes this fairly flexible, but no as flexible as Type SO in rubber neoprene, but you won't have to worry about the jacket or insulation breaking down over time due to sunlight, heat, or chemical exposure.

        The Miller Manual shows the unit wired directly to a fused disconnect. Ideal if the unit is not being moved. I would still use a disconnect or properly sized breaker while still using the plug and recepticle. Single Phase applications can use 30A 230V Dryer Plugs or Full KVA 50A Plugs without much trouble. You can even use 3 Pole or 4 Pole Twist Lock devices without much issue. These can be found at Lowes or Home Depot without much fuss. This amount of overkill is not too bad.

        However, for 460V 3 Phase, I have only seen Pin and Sleeve connection devices used and they are not cheap. These are only available at industrial suppliers like Ganger or electrical supply houses like Rexel Electric. For an industrial setting, this is ideal. For home or home shop, this amount or overkill is a bad thing.

        My $0.02:

        For Industrial: Use 50 feet of #12/4 cable with pin and sleve device with proper sized fused or circuit breaker disconnect. Good for 230/460V 3 Phase.

        For Home/Shop: Use 50 feet of #8/3 or 8/4 cable with 50A 240V Full KVA plug or 3 Pole or 4 Pole Twist Lock Device with proper sized fused or circuit breaker disconnect. Good for 115/230V 1 Phase.

        Comment


        • #5
          Sorry about the confusion. In you origanal post you asked for cord size for 460@ 20 and 30. Looking at the manual specs. amperage at 460/3 phase on that machine is 6 amps. So yes you could use 14 gauge cord. I don't know if I'd go 400' with it. I'd go 14 to 100', 12 to 200' and 10 to 400'. Bigger is better, or so they say. TJ

          Comment


          • #6
            Originally posted by flukecej
            For Home/Shop: Use 50 feet of #8/3 or 8/4 cable with 50A 240V Full KVA plug or 3 Pole or 4 Pole Twist Lock Device with proper sized fused or circuit breaker disconnect. Good for 115/230V 1 Phase.
            Thank you for the very detailed explanation. Gonna print it out for reference. I think I will opt for a fifty foot 8/4 which I can use for single of 3 phase. Will be heavier but I will only need the one cord for single of three pahse. I don't have three phase at the house but I do at my irrigation pump which I can easily tap into. I bought the dynasty 200dx because of its light portability anfd feed flexability. I haven't even fired it up yet<smile> Another nice thing about this machine is that if I do need to go several hundred feet I can do so with a spool of SO 14/4 hard wired.

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            • #7
              [QUOTE=TJsparks]Sorry about the confusion.

              Naw, no apology necessary, I was the confused one, still am. Hey, never had a welder that I can plug into any old plug before. Gonna be interesting. Thanks for the input TJ

              Comment


              • #8
                Originally posted by bfloyd4445
                Was thinking of making a 460v extension cord of 50 feet. Anybody done this? I can't seem to find any suitable plugs and receptacles. if 460 3phase is available you can use #14 wire for extension cords making long ones very light and compact.
                Where are you looking? All the Home Depots and Lowe's? Try a real electrical supply house and you will find everything you need.

                Just because it's 460-480V doesn't mean you can pick a wire gauge already. You need to know the needed amperage, which will, of course, be smaller than the equivalent power needs in a smaller voltage.

                Make sure the cords you use for the extension are rated for 600V and not 300V. Both are common.

                EDIT: I Just reread your subject line. You need #10 wire for 30A, regardless of voltage.
                Last edited by MAC702; 08-16-2006, 06:35 PM.

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