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  • Wire size?

    The oven elements I'm using are going to only pull about 22 Amps(5170 watts). I plan on installing a new 30Amp circuit about 25' from the service panel using 10Ga wire.

    Where I am confused is what size wiring do I need for the service cord(from oven to receptacle) and also the hi-temp wire size going to the elements. In looking at various wire size calculators, and based on the amp draw and distance, this oven should only require 14Ga wiring?
    Last edited by ed_denu; 08-11-2007, 12:24 PM.

  • #2
    Re: Wire size?

    the service cord should be able to handle the full amperage draw as the load is then divided & sent to each element. if you're using 10 ga. from the service panel u should use the same to feed the oven. the amperage draw per element determines the size wire for each. how many elements are you using? you can use light ga. wire for the elements. for instance this 18 ga is rated for 23 amps. 8240K31 @ McMaster. if you are using to elements they will pull 11 amps each. have you verified their resistance?
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    • #3
      Re: Wire size?

      I agree somewhat, but the length of the run makes a difference in what is required also, plus if you plan to run other loads from the outlets like air compressor and oven both. You would need to run wire heavy enough for both loads and a breaker big enough for both loads, but wire to each load could be much smaller than from breaker box to outlets.

      If 25' from breaker box to outlet near oven you may need a heavier wire than just 5' from outlet to oven.
      In any case the wire from outlet to oven must support the full load of the oven running at full blast!
      If you have figured correct and 14AWG supports the load then go with 12AWG at least.
      I always oversize the wire at least one size and under size the breaker for the wire. If a problem happens a 50amp breaker will trip before a 100amp wire burns! A short in a 30-40amp device should still trip a 50amp breaker.

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      • #4
        Re: Wire size?

        There's plenty of safty factor built in already with regards to standard wire/breaker load ratings, no need to go overboard.

        For the oven power cord, 10ga wire will suffice.
        26 amps sounds like 2 x 3000Watt elements. If that's the case, use 14ga high temp wire for the elements.

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        • #5
          Re: Wire size?

          The 30 amp breaker and 10 ga wire to the receptacle will be dedicated to the oven only.

          For the oven electronics I plan on using a single 40 amp SSD controlling both 2585 watt elements. I was looking at using the 842 degree wire(8209K17) from McMaster. It's a 14ga wire rated at 55 amps. I guess this is where I get a little confused. Typical 14 ga romex is usually rated at 15 amps while this high temp wire is rated at 55 amps.

          Also, this is the wire gauge calculator I have been looking at.

          http://www.csgnetwork.com/wiresizecalc.html

          If I calculate the total wire run of this setup, it computes that I only need 14 ga wire for the entire run(23 amps, 240 volt, 50 foot maximum length)? Do house wiring circuits always assume a longer distance run, thus the limitations of 15amps/14ga wire, 20amps/12ga wire, etc.

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          • #6
            Re: Wire size?

            i was told by electrical guys that unless the run is long (250' plus) that the standard specs in the code book are fine...ie 30amp 10ga, 20amp 12ga etc.

            tho it never hurts to oversize (except to your wallet). not sure about the other ratings that are stated at mcmaster.

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            • #7
              Re: Wire size?

              Thanks everyone for the replies. My question wasn't so much as to the wire size for the outlet as it was for the internal wiring within the oven.

              For the outlet my intent is to use 10 ga wire and a 30 amp breaker(per NEC). I'm thinking that within the oven I could use 14 or 12ga hi temp wire. The wire from McMaster is rated 55 amps for 14ga and 75 amps 12 ga(with some de-rating if multiple conductors or within conduit).

              From what I have been able to research there is a difference between the requirements for house wiring using the NEC and chassis wiring which is what I believe would apply to wiring within the oven.

              Even regular 14 ga wire has a chassis rating around 32 amps from what I've seen in various tables.

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              • #8
                Re: Wire size?

                Originally posted by ed_denu View Post
                Thanks everyone for the replies. My question wasn't so much as to the wire size for the outlet as it was for the internal wiring within the oven.

                For the outlet my intent is to use 10 ga wire and a 30 amp breaker(per NEC). I'm thinking that within the oven I could use 14 or 12ga hi temp wire. The wire from McMaster is rated 55 amps for 14ga and 75 amps 12 ga(with some de-rating if multiple conductors or within conduit).

                From what I have been able to research there is a difference between the requirements for house wiring using the NEC and chassis wiring which is what I believe would apply to wiring within the oven.

                Even regular 14 ga wire has a chassis rating around 32 amps from what I've seen in various tables.

                Careful when looking at those chassis tables, they assume ambient temperature and unbundled wire. Personally, I'd stick to the household wiring code like someone already mentioned.

                Usually it takes at leat 8ga wire for 55amps. 50+ amps out of 14ga doesn't make any sense at all.

                I'd use the 14ga wire, but run seperate wires for each element. (13amps each).

                What's a SSD? Do you mean SSR? If so, make sure that the SSR has a good heatsink. Ask me how I know...

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                • #9
                  Re: Wire size?

                  Originally posted by BottleFed70 View Post
                  What's a SSD? Do you mean SSR? If so, make sure that the SSR has a good heatsink. Ask me how I know...
                  That would be a typo! Should have been SSR. It's rated 40A and I do have a heat sink. I will monitor the SSR temperature when I first start the oven.

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                  • #10
                    Re: Wire size?

                    Originally posted by BottleFed70 View Post
                    Careful when looking at those chassis tables, they assume ambient temperature and unbundled wire. Personally, I'd stick to the household wiring code like someone already mentioned.
                    Your right about the wire being rated for ambient temperature, but at around 400 degrees, the multiplier is .82, or still around 45 amps for 14 ga. Placed into conduit would further reduce the rating, but I don't have those numbers handy.

                    I think one reason the hi temp wire is rated for higher amps is that it is a
                    "stranded nickel-plated annealed copper conductor with an
                    insulation of glass-reinforced mica tape covered with a braided fiberglass
                    jacket". This quote from the McMaster web site.

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                    • #11
                      Re: Wire size?

                      The material for the wire is definately different, but they take this into account when assigning the "guage".

                      For example: 14ga aluminum wire is larger than 14ga copper wire as aluminum isn't as good of a conducter.

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