Larger breaker and thicker wires!

I thought you only needed thicker wires for higher amps? Should go without saying, but I am not a certified electrician :-)

I only have a PhD from YouTube (Electroboom)

The voltage is always going to be the same because the voltage is determined by the transformers leading to your service panel. The breakers break when you hit a certain amperage for a certain amount of time, so by installing a bigger breaker, you allow more amperage.

If you actually had an electrician do it, I doubt they would've installed a breaker if they thought the wiring wasn't sufficient. Truth is that you can indeed get away with a 20A circuit on 14 AWG wire if the run is short enough, though 12 AWG is recommended. The reason for this is voltage drop; the thinner gauge wire has more resistance, which causes more heat and voltage drop across the wire over the length of it, which can cause a fire if it gets sufficiently hot. I'm not sure how much risk you would put yourself in if you were out-of-spec a bit, but I wouldn't chance it personally.

Could you not just run a 240 volt outlet on existing wiring built for 110v? Just send l1 and l2 on the existing hot/neutral?

You can, 240V on normal 12/2 Romex is fine. The neutral needs to be "re-labeled" with tape at all junctions to signify that it's hot, and then this practice is (generally) even code compliant.

However! This strategy only works if the outlet was the only one on the circuit, and _that_ isn't particularly common.

Although this exists, as a layperson, I've rarely seen it. There is the NEMA 6-15R receptacle type, but I have literally none of those in my entire house, and I've really never seen them. Apparently they're sometimes used for air conditioners. Aside from the very common 5-15R, I see 5-20R (especially in businesses/hospitals), and 14-30R/14-50R for ranges and dryers. (I have one for my range, but here in the midwest electric dryers and ranges aren't as common, so you don't always come across these here. We have LNG ran to most properties.) So basically, I just really don't see a whole lot of NEMA 6 receptacles. The NEMA 14 receptacles, though, require both hots and the neutral, so in a typical U.S. service panel it requires a special breaker and to take up two slots, so definitely not as simple of a retrofit.

(Another outlet type I've seen: I saw a NEMA 7 277V receptacle before. I think you get this from one phase of a 480V three-phase system, which I understand is ran to many businesses.)

If you drive an electric car in a rural area you might want to carry around 6-30 and 6-50 adapters because most farms have welders plugged into those and that can give you a quick charge. And also TT-30 and 14-50 adapters to plug in at campgrounds.

NEMA 6s are extremely common in barns and garages for welders. 6-50 is more common for bigger welders but I’ve also seen 6-20s on repurposed 12/2 Romex as the parent post was discussing used for cheap EV retrofits, compressors, and welders.

5-20R/6-20R is also somewhat commonly used by larger consumer UPS for your computer, router, etc.

NEMA 6 is limiting because there’s no neutral, so everything in the device has to run on 240V. Your oven and dryer want 120V to run lights and electronics, so they use a 14 (or 10 for older installs) which lets them get 120V between a hot and the neutral.

Oddly, 14-50 has become the most common receptacle for non-hardwired EV charging, which is rather wasteful since EV charging doesn’t need the neutral at all. 6-50 would make more sense there.

Reasons why it's nice to have a 14-50 plug in your garage rather than a 6-50:

1: when an uncle stops by for a visit with his RV he can plug in.

2: the other outlets in your garage are likely on a shared circuit. The 14-50 is dedicated, so with a 14-50 to 5-15 adapter you can more safely plug in a high wattage appliance, like a space heater.

1 is why we ended up with 14-50 as the standard, too. Before there was much charging infrastructure, RV parks were a good place to get a semi-fast charge, and that meant a charger with a 14-50 plug.

2 is something I never thought of, I’ll have to keep that in mind.

> You can always have an electrician install ...

If you own the house, sure. Many people don't.

Without upgrsding the wiring to a thicker gauge? That's not code compliant and is likely to cause a fire.

Sorry just to specify, it was more like a 20 amp I think (I will verify), it wasn't like I was going way higher.

I don't remember whether he ran another wire though. It was 5 years ago. Maybe I should not be spreading this anecdote without complete info.

He was a legit electrician that I've worked with for years, specifically because he doesn't cut corners. So I'm sure he did The Right Thing™.

There is a chance he did not run new wires if he was able to ascertain that the wire gauge was sufficient to carry 20 amps over the length of the cable. This is a totally valid upgrade though it does obviously require you to be pretty sure you know the length of the entire circuit. If it was Southwire Romex, you can usually tell just by looking at the color of the sheathing on the cable (usually visible in the wallboxes.)

If this is north america we're talking about, then 14 gauge is the standard for 120V 15A household circuits. By code, 20A requires 12 gauge. You'll notice the difference right away, it's noticeably harder to bend. Normally a house or condo will only have 15A wires running to circuits in the room. It's definitely not a standard upgrade, the 12 gauge wire costs a lot more per foot, no builder will do it unless the owner forks over extra dough.

Unless you performed the upgrade yourself or know for a fact that the wiring was upgraded to 12 gauge, it's very risky to just upgrade the breaker. That's how house fires start. It's worth it to check. If you know which breaker it is, you can see the gauge coming out. It's usually written on the wire.

I was actually under the impression that it is allowed depending on the length of the conductor, but it seems you are right. The NEC Table 15(B)(16) shows the maximum allowed ampacity of 14 AWG cables is 20 amperes, BUT... there is a footnote that states the following:

> * Unless otherwise specifically permitted elsewhere in this Code, the overcurrent protection for conductor types marked with an asterisk shall not exceed 15 amperes for No. 14 copper, 20 amperes for No. 12 copper, and 30 amperes for No. 10 copper, after any correction factors for ambient temperature and number of conductors have been applied.

I could've sworn there were actually some cases where it was allowed, but apparently not, or if there is, I'm not finding it. Seems like for 14 AWG cable the breaker can only be up to 15 amperes.

In older houses, made from brick and concrete, that can be tricky to do. The only reason I can have my computer on a separate circuit is because we could repurpose the old three phase wiring for a sauna we ripped out. If that had not been the case, getting the wires to the fuse board would have been tricky at best.

New homes are probably worse than old homes through. The wires a just chucked in the space been the outer and inner walls, there's basically no chance of replacing them of pulling new ones. Old houses at least frequently have piping in which the wires run.

You need to increase the wire diameter as well if you go that route. Running larger breakers on 10A or 15A wiring is a recipe for bad stuff.