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I bought an oven over a year ago, but I never got around to installing it. I just mounted it in the kitchen without turning it on.

I finally had the wiring done yesterday (I needed a new 4-wire configuration while the kitchen only had a 3-wire option). Wiring went successfully.

The problem:

The oven display turns on, but nothing else works—not the heating or bulb.

The circuit breaker never tripped. Moreover, the display on the oven works, so that should mean it is receiving full electricity.

This is making me think I have a faulty oven.

That said, should I also look into the breaker? On the one hand, it seems the breaker is working fine given the oven display works.

But I have limited knowledge on circuit breakers. Is it possible for a breaker to allow a low current just enough to power the display, but not enough to power the heating element? Is this even possible?

Wiring: is there a check I can do to eliminate an issue with the wiring?

Peter Mortensen
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SamuraiJack
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    @Triplefault I checked the voltages and it’s just more puzzling . Each line shows 120v but 0 between them. So I thought the breaker was Damaged. However the breaker passes a continuity test (when I pulled it out to check). That’s the first puzzle. Next I noticed an existing 2 pole breaker (washer dryer). That showed 240v. So I moved the oven wiring to the existing breaker and lo and behold - the oven now works! But here’s the next puzzle - when I wired the washer dryer to the new (suspect faulty) breaker, that’s working too. I’m confused on these results. – SamuraiJack Jul 31 '23 at 04:19
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    A picture of your breaker box may help figure out what's up. As @smitelli commented below, at least one breaker box type can allow accidentally mounting 240V double breakers on the same power leg. – Triplefault Jul 31 '23 at 14:40
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    A picture is **critical** here. I suspect you have **half size** (a.k.a., tandem or double-stuff) breakers. This lets you double the "circuits" in your panel. The problem is that, depending on the panel (manufacturer, type, particular breakers, whether things are installed correctly, etc. - lots of factors) it is *possible* to install a pair of half-size breakers so that they will produce 240V between hots and also possible to install **the same breakers** (in some panels) to get 0V between hots. – manassehkatz-Moving 2 Codidact Jul 31 '23 at 15:11
  • @manassehkatz-Moving2Codidact That's a really good point, although I didn't know half-size double breakers came in the 40+ amp ranges (which I assume the owner has for an oven). – JBH Jul 31 '23 at 16:52
  • https://www.homedepot.com/p/GE-Q-Line-40-Amp-1-2-in-Single-Pole-Circuit-Breaker-THQP140/100174448 – manassehkatz-Moving 2 Codidact Jul 31 '23 at 18:48
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    "I finally had the wiring done" was this an electrician that did this, your neighbor, Bob the Handyman? If you paid someone (hopefully a licensed electrician) for her services, then call her back to have her fix the issue. If it was you/your neighbor/Bob/other, well... It may be time to pay someone who actually know what he's doing. – FreeMan Aug 01 '23 at 16:36

3 Answers3

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If you had to install a 4-wire supply, you're probably on North America style split phase power. The two power leads provide power in "opposite phases" so double voltage can reach the appliance.

If one leg of the power is not connected, then control circuits might function but not the heating.

If you have enough safe electrical skills you can use a voltmeter to check if the two power lines each show voltage to the neutral and twice the voltage to each other. If you don't get twice the voltage across the power lines, the wiring and/or breaker needs to be checked.

Triplefault
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    >"Is it possible for a breaker to allow a low current just enough to power the display" OP asking this suggests the only safe option to step away slowly and call an electrician. – Jeffrey Jul 31 '23 at 16:19
  • @Jeffrey, yes, that's a good possibility: lack of skills can make diagnosing this a dangerous DIY proposition, – Triplefault Jul 31 '23 at 18:32
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Based on your multimeter readings, you have a problem with your breakers

If you're reading zero volts between the two breakers there is most definitely a problem. You should be reading 240v between the two breakers.

Most people don't know that their 120v house is actually 240v. Two 120V lines are brought in, each line having a different phase. Between the two phases, you get 240v. If the two breakers are on the same phase then you'll read 0v between them. They must be one on each of the two phases.

  • If you're using a double breaker, this should naturally happen.
  • If you're using two single breakers, it's easy to make the mistake.

It is against electrical code and very unsafe to use two single breakers. I don't know if that's what you're doing, but if you're reading 0v between the two breakers, then I'm really hoping that you're trying to use two single breakers. If you're using a double breaker like you should be, then it means both channels in your panel are wired to the same phase. That should never be the case and is a very big deal.

Please tell me you happen to be using two single breakers. Then go buy an appropriate double breaker and replace the two single breakers with it. Your oven should work at that point.

NOTE #1: Power to the display is not sufficient proof that your appliance has "full electricity." That display is operating on only one of the two phases. If both phases are not present, the heating ability of your appliance will not work.

NOTE #2: So say it again... It's very dangerous and against code to use two single breakers when 240v is required. The reason is that if something goes wrong on one phase, you WANT both phases to disconnect. That's why double breakers have a pole physically connecting both switches... to guarantee that if one trips they both trip. Yes, you could save a buck by using two single breakers rather than a double breaker. if you insist on doing this, you must obtain an approved handle tie and insert it across both switches to ensure that they both trip together. (My thanks to @Jack for pointing that out). Frankly, don't do that. Just buy a double breaker.

NOTE #3: If after reading my answer you believe something is confusing, please take a photograph of the breakers with something like some tape or arrows drawn into the picture indicating which two breakers we're talking about and add it to your post, then let us know that you did that.

NOTE #4: My thanks to @manassehkatz-Moving2Codidact for pointing out that you might be using one single-wide double breaker. Half-size breakers are a convenient way to extend breaker panels, but they're not expected to be used without the guidance of a trained electrician. If you're using a half-size double breaker, that's the problem.

JBH
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    "If you're using a double breaker, this should naturally happen." I've got a GE half-inch panel, and it's pretty easy to get "off by one" and install both halves of a double breaker onto the same phase. – smitelli Jul 31 '23 at 11:20
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    "if this is what you want to do you must put a screw through the holes on both switches to ensure that they both trip together." This is a code violation. Approved handle ties are the only way to do this. – JACK Jul 31 '23 at 12:36
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    Physically connecting the handles of 2 single breakers will _not_ guarantee that they will trip at the same time. This just ensures that they're turned off at the same time by someone working in the panel. The breaker can trip without moving the handle at all exactly _because_ people will handle tie breakers and the "good" one could prevent the "bad" one from tripping. – FreeMan Jul 31 '23 at 12:36
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    @smitelli How can you get "off by one" with a double breaker and tie into both phases? Is that panel not designed with interdigitated distribution to *guarantee* that can't happen? Personally, I've never seen a panel designed that way. – JBH Jul 31 '23 at 15:10
  • You can be "off by one" when using half-size breakers. Properly designed and installed, a **pair** of half-size breakers will only fit in a single regular slot, so that to get a 240V pair you use a **quad** with inner pair and outer pair getting 240V. Even then, they may or may not be designed to trip together. But it is possible in some cases (especially with installers not understanding how things work) to end up with two hots going to a pair that are on the same leg. As far as common trip vs. common shutoff: As I understand it, common shutoff (which you get from a handle tie or from an – manassehkatz-Moving 2 Codidact Jul 31 '23 at 15:32
  • actual double-breaker) is required for a simple MWBC (only feeding 120V loads) and for any 240V circuit. But for an MWBC serving both 120V and 240V loads, or for a combination 240V/120V device (oven, dryer) you **must** have common trip (which you only get from a double breaker and not from a handle tie) because otherwise the 120V components could overload and only trip one hot but the other would still be live. (In a 240V only circuit, that isn't terribly likely, and in a 120V only MWBC it wouldn't cause a problem.) – manassehkatz-Moving 2 Codidact Jul 31 '23 at 15:34
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    @manassehkatz-Moving2Codidact: On a "pure" 240V circuit, one could easily have one breaker trip without the other doing so, but mixed circuits have a hazard that isn't present in a 120-only MWBC or a 240V-only circuit. If one had an MWBC that included a 240V plug, and were to plug in a 240V heater, the breaker for one phase could power equipment on the other phase through the heater. – supercat Jul 31 '23 at 19:25
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This may sound stupid, but is it possible you need to set something on your oven? Ours has the same symptoms after a power disruption until we press a particular combination of buttons.

https://www.fixmywhitegoods.co.uk/oven-not-working-chek-your-timer

user79408
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    OP updated to note that the oven works properly when its wiring is connected to a different breaker, suggesting the issue is with the breaker. – Armand Aug 01 '23 at 08:06