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I have an induction cooktop/stove in a California condo built in 2011-2012.

Recently, I had to pull the cooktop electrical and discovered that the stove has a 3 wire harness (red, black, yellow/green). The building has 4 wires (red, black, white/neutral, and ground).

The builder connected the stove's yellow/green to the building's neutral and left the building's ground unconnected.

Per the manual, I believe they should have connected the stove's yellow/green wire to ground. However, the manual indicates it would be a bare wire and it's actually a yellow/green.

What's the correct way to wire the stove up to code?

wiring

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    The yellow-striped wire is green, not black.
    – Ecnerwal
    Oct 19, 2022 at 21:32
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    If you were the one who had the stove installed originally, call the installation company (whether electrician or Best Buy, or whoever did it) and demand that they fire the hack that did this! This is a very illegal installation in 2011 or later.
    – FreeMan
    Oct 20, 2022 at 14:37
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    @FreeMan, I'm pretty sure it was done when the place was built, as all my neighbors' condos have the same cooktop. My neighbors and I have been discovering all kinds of issues and shortcuts from the initial build.
    – James
    Oct 20, 2022 at 16:17
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    @James definitely worth sharing this info with your neighbours then, A fire in anyone's unit will affect you all.
    – Criggie
    Oct 20, 2022 at 23:20

3 Answers 3

19

This appears to be a combination of errors:

  • Neutral vs. Ground

The installer is used to typical US 240V/120V stoves which require neutral. So they naturally connected the "not black, not red" wire to neutral. Incorrectly, because that is actually a ground wire and they just didn't know what they were looking at. What they should have done was connected ground wires together and capped the neutral because it is not needed for this stove.

  • Yellow/Green

I'll bet it isn't yellow/black but rather yellow/dark green. Ground can be bare, green or yellow/green.

  • 240V-only

A typical US stove uses 240V for heating elements and 120V for lights and controls. But there is no reason these days to not use 240V for everything (except inertia), as controls are generally running off of a conversion to low voltage DC (so 120V or 240V as the starting point doesn't matter much) and lights are LEDs (again, low voltage DC, not line voltage AC). So a savvy manufacturer may choose, particularly with a new design such as an induction cooktop, to skip any 120V parts altogether. Which conveniently means the same exact cooktop can be used around the world (e.g., 208V - 250V) with no changes needed.

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    Yup, it was yellow/green, edited and fixed!
    – James
    Oct 19, 2022 at 21:51
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    I would expect that oven lights will use incandescent lamps for years to come, since such lamps work equally well throughout an oven's temperature range. On the other hand, I would think that running a 120V bulb from 240V using a triac-based dimmer circuit should avoid the need for a 120V mains supply.
    – supercat
    Oct 20, 2022 at 16:06
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    @supercat a 220-240V heat resistant lamps are a normal thing in most of the world, and probably cheaper than a 240-120V transformer circuit.
    – Criggie
    Oct 20, 2022 at 23:22
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    @Criggie: Using a lamp that isn't readily available in the US would give one's product a reputation of being hard to repair, and convincing US retailers to stock an extra kind of lamp would likely cost more than a cheap triac (not transformer)-based dimmer circuit.
    – supercat
    Oct 21, 2022 at 14:23
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    @supercat In the old days of "oven light = 40W incandescent appliance/heavy-duty Edison base bulb", you would be correct. But many ovens for a long time have used tiny halogen bulbs that you can't just walk into a regular store and buy, so being a special-order part isn't such a big deal. Oct 21, 2022 at 15:31
16

According to the linked manual, you are correct and the installer should not have connected anything to the condo's neutral wire.

The red and black cooktop wires are for the 240V supply and the yellow w/green stripe is the equipment ground.

Correct installation would be:

  • Cooktop Red > Branch Circuit Red
  • Cooktop Black > Branch Circuit Black
  • Cooktop Yellow w/Green Stripe > Branch Circuit Bare

There is no neutral wire on the cooktop so the condo white should be capped off and left in the box.

12

In 1966 when they required grounding for everything else, appliance makers got an exception allowing hot-hot-neutral 3-wire connections for ranges and dryers. "What could go wrong?" 4-wire connections were strongly encouraged, then mandated in NEC 1996.

As such, appliance installers generally view the world as 2 types of connections: 3-wire Hot-hot-neutral, or 4-wire hot-hot-neutral-ground.

Becuase the induction cooktop doesn't have an oven, it doesn't need an oven light and has no need for neutral. Therefore it is hot-hot-ground which the installer was unfamiliar with.

Feel free to correct it. Cap off the neutral securely as it can be hot in some conditions. That's why it's insulated.

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    And just to confirm NEC 1996 would have applied when my condo was built in 2011/2012, and thus the installer did not perform the install up to code?
    – James
    Oct 19, 2022 at 21:50
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    @James that's correct. But I think it was an honest error. Not sure if there's a payday involved in going after them for it. Oct 19, 2022 at 22:07
  • Not planning to! Just adding it to the list of errors I've had to fix...
    – James
    Oct 19, 2022 at 22:52
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    @James Depending on what county you are in, you would probably have been under the CA Electrical Code 2010 (yep, we have to have our own, although it is really the 2008 NEC with some CA-specific additions). Either way, that neutral-ground connection is not code-compliant. Easy fix though.
    – Chris O
    Oct 19, 2022 at 22:57
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    Easy to fix, but should be reported back to whoever did the installation. An electrician should have known better. Best Buy or whatever appliance company that hired an installer should know that their subcontractor is doing illegal work and fire them. Of course, 10 years later, said employee is likely long gone...
    – FreeMan
    Oct 20, 2022 at 14:38

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