Have a seriously weird issue.

I have a dryer outlet that is showing fine for both 120V's (checked against ground and common) but across them there is no 240.

My initial thought was that they were on the same hot leg but it is connected to a quad tandem breaker with the oven. The oven works fine.

enter image description here

Any ideas? Do you think the breaker might be bad? I know that's rare but I can't think of anything else.

Appreciate any ideas/insight.

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    Aren't the red and black going to the same screw on that tandem breaker? Or is that just a weird picture? – JPhi1618 Jan 24 at 16:32
  • Its just the view on the picture. I pulled the breaker and made sure. It totally looks like that though :-) – JoeyKong Jan 24 at 16:33
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    I honestly don't see any way the black and red wires are going to separate screws, but if you say so... That would also explain your issue perfectly. – JPhi1618 Jan 24 at 16:34
  • I agree. It totally would. I will double check but I am 99% sure. I would feel like a moron if that is the case... – JoeyKong Jan 24 at 16:36
  • The moment I read the title, I knew a double-stuff breaker would be involved. – Harper - Reinstate Monica Jan 24 at 17:05

Answer pending verification of photo...

It looks like someone may have been using that dryer outlet for a large 120v appliance, probably with some homemade adapter. In your picture it seems like both the red and black wires are attached to the upper screw on that double pole breaker. This would put them both at 120v to ground, but zero volts between each other.

Having parallel paths in a circuit like that is not allowed, but it doesn't matter much now because you're going to fix it. Once the two wires are attached to the right screws you should be fine. Just to double check that there is not an issue with your panel, measure the voltage between the two screws on the breaker. That should be 240v, of course. If it's not, there could be a compatibility issue with that breaker in that panel, but like you say, the stove works, so I don't think it there would be an issue here. Turn the breaker on and off to reset it if the voltage is not present.

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  • I will take a look this afternoon and make sure that they aren't going to the same screw. I am sure I put them in correctly when I pulled the breaker but there is always a chance I am wrong and you are correct. It would explain everything. – JoeyKong Jan 24 at 16:50
  • That breaker panel looks very tight... I wouldn't feel bad at all if that happened. And if I'm wrong, I'll remove the answer - I just wanted to have it because I had a minute to post it now. – JPhi1618 Jan 24 at 16:51
  • Went back to look and the black wire must have been loose. It was not in the terminal and it was touching the other one. Face palm moment for not checking it. Wish it wasn't touching the other one so it would have been more obvious. Thanks for the help guys!! – JoeyKong Jan 25 at 0:59
  • Ah, ok. That makes sense. There is a torque spec on those connections. Of course, make sure they are tight. – JPhi1618 Jan 25 at 1:01

Possible fire hazard!?

Most likely more important then the asked subject: The area of the 2 left contact screws of the double breaker with red handles just above the quad breaker seems to be molten resp. overheated. The breaker must be switched off and replaced, all connected devices must consume not more then 20A in sum - unless a load shedding relais is used. There is a big fire danger - most domestic fires are started by electric devices/equipment.

To the subject: what is the voltage between both hot phases?

If it is below some 10V, most likely it is the same phase - small voltages can be measured with high ohmig test meters (10MOhm), since there is always some inductive or capacitive voltage on a cable.

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  • I see what you are seeing but those are spider webs not melted metal. I might as well replace it since I will be in there anyway. I will go ahead and do that. Its got to be 30+ years old. – JoeyKong Jan 24 at 17:02
  • "all connected devices must consume not more then 20A in sum " - uh, no. Perhaps this is the way the electrical system works in your part of the world, but in this part of the world breakers and busses are typically fine with considerably larger loads. i.e. my 200A panel has busses that will safely carry 200A, and I have a 100A branch breaker that is listed to be plugged into that panel. – Ecnerwal Jan 24 at 17:37
  • @Ecnerwal The statement was meant for the shown breaker, given it will be replaced by a breaker of the same rating, i.e. 20A. The bus is certainly rated for higher loads, but unless all downstream cables' and outlets' ratings are not checked for higher load, it is safe to assume the maximum current is 20A for each of these 2 breakers with red handles. – xeeka Jan 24 at 17:48
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    Yeah, that looks like the work of Panel Spiders. – Harper - Reinstate Monica Jan 24 at 18:57
  • @Harper-ReinstateMonica But how to explain the very homogenous and very deep black color at the far left side? This color looks like carbonated residuals from overheated plastics. It seems to be the only area with this color (dark grey being the basic color) and it seems to be the only area with no dust or scratches like seen in all other areas. F.e., all edges between the individual breakers seem to have some white colorings due to high wear or white dust except the edges in the dark black area. Maybe panel spiders like it hot or a surface which is easy to hold/glue on? – xeeka Jan 25 at 6:24

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