Converting a 3-phase outlet?

drewmo Posted By drewmo, Jul 3, 2019 at 12:09 PM

  1. drewmo

    drewmo
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    We're planning on swapping out our electric range with a propane unit. Is there a simple way to convert the 3-phase outlet to 120V? Or is running a new wire from the box the best way to go?
     
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  2. johneh

    johneh
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    Are you on fusses or circuit breakers and what make ?
     
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  3. begreen

    begreen
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    Wait, why would there be 3 phase at a range outlet? Do you mean 3 wire?

    Be careful. The range outlet is high amperage so the circuit protection would be incorrect for a regular 12-20amp receptacle. Will you be changing the breaker to a single-phase, 20amp breaker? If there truly is 3-phase then note that 3-phase comes in two flavors Delta and Wye. You need to determine which is at the panel first. The voltage can be an indicator. Do you have 208v or 240vac?
     
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  4. bholler

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    I assume you mean just 220v not actually 3-phase. If it is just 220 yes it is possible but not the right way to do it. I would run a new 12/2 wire for the 110 outlet.
     
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  5. Dobish

    Dobish
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    if you are going to run a new 12/2 wire, I would just run a new one and keep the 220 outlet where it was in case you ever want to go back to electric for any reason.
     
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  6. fbelec

    fbelec
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    dobish has the right idea. that's what i would do. you need to run a new line 12/2 (yellow wire) besides the 20 amp circuit breaker won't take more than a 10 ga wire the stove should be a minimum of 8 copper or 6 aluminum
     
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  7. semipro

    semipro
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    Romex or NM wire is now color coded to indicate the conductor size. White is 14 gauge and yellow is 12 gauge. Its the sheath that goes around the conductor wires that's colored. The conductor wires within the sheath are typically white and black with a bare ground conductor. Red wire is used in 3-conductor NM (3 conductors + ground).
    More here: https://www.thespruce.com/what-does-romex-or-nm-mean-1821530
     
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  8. Ashful

    Ashful
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    But again, 3 conductors + ground does not indicate 3 phase (unless you’re in a commercial delta configuration, which isn’t even available to residential customers). It’s single phase 230V black/red) + common (white) + ground. You should measure 115V nominal from black or red to white or ground, 230V nominal from black to red, and zero from white to ground.

    BTW, it IS legal within NEC to run a 110V appliance from white to black or red on a 230V circuit. But the receptacle hardware must be matched to the load protection device, and I’m not sure how to handle the wire gauge issue at the receptacle. It shouldn’t be an issue to find a 20A dual pole breaker with a cage clamp rated for his existing wire gauge, but finding a NEMA 5-20 receptacle with wiring connections rated over AWG-12 may be a challenge. I don’t believe you are allowed to change wire gauge outside of the receptacle box itself (check me in that), and fitting lugs + AWG-12 receptacle pigtails all inside one receptacle box would be damn near impossible.

    I know all this because my shop is wired entirely on a 230V/115V dual system. I ran all dual pole breakers on my 20A general purpose circuits, with AWG12/3+G to all 2-gang boxes. One duplex receptacle in each box is NEMA 5-20 the other duplex receptacle in each box is NEMA 6-20, using one hot + common at each box to get 115V, so I have 115 V and 230 V available every receptacle location. This was my own idea, but verified as legal by four different electrical contractors that quoted my job, and the work was done by one of our larger electrical contracting firms who does mostly commercial work.
     
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  9. drewmo

    drewmo
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    It appears when it comes to even simple electrical, I'm way over my head! Thanks for all the comments, but I might be needing to hire a pro on this one.
     
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  10. paulnlee

    paulnlee
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    Buy a dual fuel and you don't have to change a thing
     
  11. Don2222

    Don2222
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    In your case since both outlets are 20 amp then the wire feeding them is correctly sized and the breakers are also sized correctly.
    To go from 230 VAC 40 amp for an electric range down to 120 VAC 15 amp circuit may require smaller gage wire. Just my 2 cents
     
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  12. paulnlee

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    Like I said over a month ago, go with a dual fuel and no wiring change necessary.
     
  13. Ashful

    Ashful
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    I believe it is still permitted to use the larger gauge wire, if the lugs on all wiring devices are rated for that gauge. Usually not an issue at the breaker end, but it will be an issue finding a NEMA 6-20 receptacle that is rated for AWG-8. Additionally, it is not permitted to change gauge within a branch circuit, unless it is at the load, essentially pigtails in the receptacle box. Check your code, but I believe this could be resolved with AWG-12 pigtails on a NEMA 6-12 receptacle, in a box large enough to lug or nut them to the AWG-8, and a new 20A breaker on this dedicated circuit.

    If it is not a dedicated circuit, then things get more tricky, but I believe it is dedicated.
     
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