50 Amp Range replaced with oven / cooktop combo

Discussion in 'Electrical Forum discussion & Blog' started by SK78, Apr 6, 2018.

  1. SK78

    SK78 New Member

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    Michigan
    Thank you in advance for your advice...

    For a kitchen remodel I am replacing a range which is wired with a 50 Amp circuit an 6 AWG AL wire with a cooktop calling for a 30 Amp circuit and 20 Amp oven which will be installed below the cooktop.

    I saw that the code allows these two to be wired on the same circuit, but has a description on how to wire it that I do not exactly understand. How would this connection look, can I join two 10/2 wires (or the pigtails from cooktop and oven) to the 6 AWG with some Polaris IPLG6-3B use them to wire up the two units?
     
    Last edited: Apr 6, 2018
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    The circuit breaker/fuse is there to protect the wiring, not the device. So, as I understand it, up to the entry of the devices, the wiring must be sized for the circuit involved unless the devices involved say otherwise.
     
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  4. Stuff

    Stuff Well-Known Member

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    Plan is good if a 50 amp circuit as done all the time. Problem is 6 gauge AL is only good for 40 amps if NM or SE.

     
  5. SK78

    SK78 New Member

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    That is how I would have thought of it as well.

    However, there is this reference in the code:
    Table 220.55 in the NEC, footnote 4:
    1. Branch-Circuit Load. It shall be permissible to calculate the branch-circuit load for one range in accordance with Table 220.55. The branch- circuit load for one wall-mounted oven or one counter-mounted cooking unit shall be the nameplate rating of the appliance. The branch-circuit load for a counter-mounted cooking unit and not more than two wall-mounted ovens. all supplied from a single branch circuit and located in the same room, shall be calculated by adding the nameplate rating of the individual appliances and treating this total as equivalent to one range.
    Also Rex Cauldwell in Wiring a House also refers to this and shows a diagram.

    So it must be approved, my question then is with the AL wire, would the Polaris connector be permissible and the correct one for the application?
     

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  6. Stuff

    Stuff Well-Known Member

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    Article 220 is not normally used for breaker or wire sizing. Read 220.40 - the section is used for the calculation to size feeders or service.

    Good point: Those grey Polaris are for copper only. Polaris black connectors are listed for connecting both aluminum and copper wires. Have to be in a junction box, though.

    https://www.polarisconnectors.com/pdfs/NSi/IPL_series.pdf
     
  7. Norcal01

    Norcal01 Member

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    Is the existing circuit a 3-wire or 4-wire feed? If 3-wire you cannot extend it, new feeds will have to be run to comply current requirements, as the 3-wire feeds are only allowed in existing installations, as soon as changes are made it's no longer existing. See NEC art. 250.140
     
  8. SK78

    SK78 New Member

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    you are correct Norcal, it is a 3-wire in a home built in 1997. Out of luck I guess. Do you know if there is a way to run a separate conductor to the kitchen rather then replacing the whole wire. Its up in a drop ceiling so I would like to avoid running that heavy 6/3 wire if possible.
     
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    It is not code compliant to run a separate ground wire to augment an existing cable. Now, if it were in a conduit using say separate conductions, yes, but not with an existing cable.
     
  10. SK78

    SK78 New Member

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    OK, thanks Jim, I guess I will be wrestling an anaconda next weekend.
     
  11. SK78

    SK78 New Member

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    One more question, my options to replace the wire are a 6/3 copper or an AL service wire from what I found. Can someone tell me what the correct AL wire designation is that I would need? Is it 6-6-6-6 SER?
     
  12. Stuff

    Stuff Well-Known Member

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    4-4-4-6 SER AL is good for 55 amps
    6-6-6-6 SER Cu is good for 55 amps
    6/3 NM-B Cu is good for 55 amps
    8/3 MC/AC/THHN in conduit Cu is good for 50 amps
     
  13. SK78

    SK78 New Member

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    Thank you!

    I had another thought.

    The induction cooktop calls for a 30AMP 3 wire circuit.
    The new oven is a 20 AMP 4 wire circuit.

    Could I use the existing 50 AMP 3 wire for the cooktop and run a new 20 AMP 12/3 for the oven?
     
  14. Stuff

    Stuff Well-Known Member

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    Repurposing the 6/2 and a running a separate 12/3 should work. The 6/2 would be hot, hot, and ground. You would then need two double pole breakers in your electrical panel.

    Technically there might be an issue that the grounding conductor needs upsized. Rule is if the wire is upsized (installing 6 AL instead of needed 8) then you need to upsize the grounding wire proportionately. So if current cable is 6-6-6 you are good but if 6-6-8 it would fail.
     
  15. Norcal01

    Norcal01 Member

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    Are the new appliances 120/240V or straight 240V? If they do not require a neutral things could be looking up.
     
  16. BiG_Mackenzie

    BiG_Mackenzie New Member

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    Texas
    I am not an expert but a standard kitchen range with four burners and an oven could draw 30, 40, or 50 amps. However, I will advise you to watch the tech blogs where is written about these devices. Before buying something, I take a look all the time on hellodiya blog where you can find more useful information about ovens, washing machines, or other devices. It was a huge help for me when I changed all devices at my home. All works till now without any problems.
     
    Last edited: Mar 23, 2021
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