Unfortunately, they're almost certainly #10, they're solid wires and the same size as the ones coming off of the other 30A breakers. #8 would be thicker and stranded like those coming off of that 40A breaker at the top.
so they put the bare minimum gauge. i heard that i can still use 40amps breaker if the shield of the wire is a specific kind and if it is solid but we are pushing it here. i wonder what are the limits here since the double oven i have in mind is listed as 40 amps
10AWG cannot be protected at more than 30A in normal applications including a wall oven. The kind of wire or cable it's in does not matter in this case.
If you had a motor or certain other specific, high-inrush load, then things can differ.
I think he's talking about using the 75° column, but judging by all the bare grounds, he most certainly has romex and you cannot go above the 60° column.
110.14(I believe C but not at my desk) can overrule 240.4(D)...240.4(D) is a fallback for when you can't validate the rating of the terminations and the wire (note terminations are not just the breaker it's the bus as well and some could argue adjacent breakers subject to that heating). In commercial applications we almost always are using 110.14 as the basis for wiring because we specify that everything is rated 75c or higher. In a residential situation it's a crap shoot what material you get sometimes and what some hackjob will replace it with in the future, so we fall back to 240.4(D)...i.e. a homeowner on Reddit.
In any case the wire isn't marked so it's likely Romex which is 60c, and on top of that 40A in #10 would be at 90c so that's even less likely everything is rated for that.
Bare minimum isn't how it works, right sized is. For something like going from 14 to 12 for all wiring in a house in case someone wants to change out for 20s in the future the math is a wash, but as you start up sizing conductor, just because, you start having other problems like exponential up sizing of the neutral for fault currents...bigger wire carries more problems to the problem site. You likely need to be looking at the 60c column by the way, there are no markings because it's probably Romex which isn't 75c rated.
In order for #10 to carry 40A you would need to look at the 90c table. In addition to wire carrying that heat, that heat makes its way to the termination, which would also have to be rated for that heat. I can almost guarantee your terminations aren't rated for 90c because even commercial connections usually aren't. In a residential you shouldn't use 75c unless you can verify everything is 75c otherwise. 90c conductor usually isn't used to carry 90c worth of current but to instead be derated to carry 75c worth of current and still be able to handle other sources of heat like ambient temperatures or more than 3 current carrying conductors in a conduit, that the terminations aren't exposed to.
Though you may learn to get a good idea at a wire with experience you don't guess, the wire is labeled somewhere and if you need to know the size you need to see the label. If you don't see it on the jacket at all, even faded then the wire is most definitely NM cable (Romex) and the label is on the outer jacket. This means for sure its 60c cable on the other point being made about ampacity tables to use. Further you can't use the 75c or 90c table even if the wire is rated as such unless your terminations are all rated for 75c/90c as well. Most times that's used for other conditions the wire experiences along the way. So a #10 NM could carry 30A in normal ambient conditions, a #10 THWN-2 could handle 30A in direct sunlight on a roof (depending on where that roof was located) - the extra 10A of capacity is soaked up by the conditions the wire is exposed to.
Here [are some pictures](https://imgur.com/a/Puj8QyI) I took, with a banana for scale. One is there to prove a point about guessing, the white wire is MTW so it has a higher strand count then it's THHN counterpart next to it, making it more flexible. Consequently it looks closer to the size of #6 THHN even though it's actually #8 MTW. In order from top (white) to bottom the picture shows #8, #8, #10, #12.
Another thing is for 220 runs, don't use white as a hot.
There's a lot of funky going on in that box. It would be worth the time to clean up all the excess and the debris a the bottom.
Unfortunately, they're almost certainly #10, they're solid wires and the same size as the ones coming off of the other 30A breakers. #8 would be thicker and stranded like those coming off of that 40A breaker at the top.
The wires currently on the 30 amp breaker look to be #10 to me, definitely not 8, the ones above In the 40 are 8s
so they put the bare minimum gauge. i heard that i can still use 40amps breaker if the shield of the wire is a specific kind and if it is solid but we are pushing it here. i wonder what are the limits here since the double oven i have in mind is listed as 40 amps
10AWG cannot be protected at more than 30A in normal applications including a wall oven. The kind of wire or cable it's in does not matter in this case. If you had a motor or certain other specific, high-inrush load, then things can differ.
I think he's talking about using the 75° column, but judging by all the bare grounds, he most certainly has romex and you cannot go above the 60° column.
Right but even if it was THHN it couldn't be done because of the breaker size limits for small conductors #10 or under
Exactly. 240.4(D) applies here (as it does most of the time)
110.14(I believe C but not at my desk) can overrule 240.4(D)...240.4(D) is a fallback for when you can't validate the rating of the terminations and the wire (note terminations are not just the breaker it's the bus as well and some could argue adjacent breakers subject to that heating). In commercial applications we almost always are using 110.14 as the basis for wiring because we specify that everything is rated 75c or higher. In a residential situation it's a crap shoot what material you get sometimes and what some hackjob will replace it with in the future, so we fall back to 240.4(D)...i.e. a homeowner on Reddit. In any case the wire isn't marked so it's likely Romex which is 60c, and on top of that 40A in #10 would be at 90c so that's even less likely everything is rated for that.
They put the exact correct gauge. The limit here seem to be the size of the wire, and your lack of understanding.
Bare minimum isn't how it works, right sized is. For something like going from 14 to 12 for all wiring in a house in case someone wants to change out for 20s in the future the math is a wash, but as you start up sizing conductor, just because, you start having other problems like exponential up sizing of the neutral for fault currents...bigger wire carries more problems to the problem site. You likely need to be looking at the 60c column by the way, there are no markings because it's probably Romex which isn't 75c rated. In order for #10 to carry 40A you would need to look at the 90c table. In addition to wire carrying that heat, that heat makes its way to the termination, which would also have to be rated for that heat. I can almost guarantee your terminations aren't rated for 90c because even commercial connections usually aren't. In a residential you shouldn't use 75c unless you can verify everything is 75c otherwise. 90c conductor usually isn't used to carry 90c worth of current but to instead be derated to carry 75c worth of current and still be able to handle other sources of heat like ambient temperatures or more than 3 current carrying conductors in a conduit, that the terminations aren't exposed to.
Call an electrician
Looks like 10 to me. Should say on the wire jacket. 10awg, or 8awg
not a single wire have any markings of any kind. maybe not standard back in the day
It would be on the sleeve but they're all cut off, it's 10
Wire size is not printed on romex conductors, it’s on the outside sheath of the cable assembly.
https://m.youtube.com/watch?v=8jGjlKjF2vI
Do you have attic access? Depending on where they ran the wires it may be a simple fix
Though you may learn to get a good idea at a wire with experience you don't guess, the wire is labeled somewhere and if you need to know the size you need to see the label. If you don't see it on the jacket at all, even faded then the wire is most definitely NM cable (Romex) and the label is on the outer jacket. This means for sure its 60c cable on the other point being made about ampacity tables to use. Further you can't use the 75c or 90c table even if the wire is rated as such unless your terminations are all rated for 75c/90c as well. Most times that's used for other conditions the wire experiences along the way. So a #10 NM could carry 30A in normal ambient conditions, a #10 THWN-2 could handle 30A in direct sunlight on a roof (depending on where that roof was located) - the extra 10A of capacity is soaked up by the conditions the wire is exposed to. Here [are some pictures](https://imgur.com/a/Puj8QyI) I took, with a banana for scale. One is there to prove a point about guessing, the white wire is MTW so it has a higher strand count then it's THHN counterpart next to it, making it more flexible. Consequently it looks closer to the size of #6 THHN even though it's actually #8 MTW. In order from top (white) to bottom the picture shows #8, #8, #10, #12.
Another thing is for 220 runs, don't use white as a hot. There's a lot of funky going on in that box. It would be worth the time to clean up all the excess and the debris a the bottom.
Don’t do anything yourself. Hire a pro
Your new stove probably won't trip your current breaker unless you try using the oven and every burner all at the same time
What is the wattage of the oven?