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I am changing out a 25-year old 240v cooktop with a new cook top. The old cooktop had 4 wires and the new one has 3.

After the white and green, the junction box has 1 set of 2 purple wires that the black wire from the stove was connected to and another set of purple wires that the red was connected to. Tracing this back to the breaker box, the 2 separate sets of wires are controlled by 2 separate fuses vs. one 2-pole 40A. The breakers are in pairs, but 1/2 of 1 pair of breakers feeds 1 set of purple wires and 1/2 of another pair feeds the other pair of purple wire. I'm not sure what to do.

  • Can I attach the 1 black wire from the new cooktop to both sets of purple wires and thus both breakers? The breakers are in pairs.
  • Do I need to put both lines on 1 2-pole, and then put the other lines on 1/2 (slim) breakers?

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Breaker box:
here's a pic of the breaker box

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FreeMan
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A Doc
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    Can you please [edit] the question to describe the wires and their inter-relations more carefully? Or some pix would be good. Do the wires have writing on their insulation? If they don't they are not purple. I need more about how the black, white and green wires are organized into cables, how they were previously connected, and which specific breaker handles the wires attach to. Note those breakers are inner/outer quadplexes, with the outers being one circuit and the inners being another. – Harper - Reinstate Monica Oct 07 '23 at 03:09
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    You have an alien problem. Looks like your panel is Westinghouse (and so the Bryant is ok) but the MP-T doesn’t belong. Needs to be replaced with a unit listed for your panel. – nobody Oct 07 '23 at 03:30
  • Can you post photos of the inside of the junction box where the cooktop wiring terminates please? – ThreePhaseEel Oct 07 '23 at 22:59
  • Wow - great questions and observations! I added more pics that will hopefully clarify. Thank you so much for your help. – A Doc Oct 09 '23 at 05:34
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    To be clear, is the new cooktop 240v as well? Does it not have a white, just having a green, and 2 not whit or green wires? – user1937198 Oct 09 '23 at 09:55
  • Those look like NEMA 5-15 outlets designed for 15amp service. What size breaker are they attached to?? Can you get a picture of the face of the cover plate showing the receptacles, and a better picture of the wiring inside the receptacle box. Also, please identify _which_ breaker(s) the oven is wired to. A picture of the inside of the panel (with the cover removed) would be most informative (if you're comfortable removing the cover). – FreeMan Oct 09 '23 at 14:06
  • The cooktop is definitely 240v. I'll should be able to get a pic of the inside of the panel and post it tomorrow. The 2 thrown breakers on the panel pic above are the ones that feed the L and R sockets in the box. You can see the faint markings next to the breakers. Both of those circuits went to the old 4-wire 240v cooktop. – A Doc Oct 10 '23 at 05:59

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