House wiring questions

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Originally Posted By: tom slick
If the neutral is shared between two circuits you need a double breaker that is tied together like the one on the lower left. That way not only are the two circuits phased correctly but it always shuts off both circuits.
You can get a kit that includes a bar to operate both breakers at once. No need to kill power to the whole box to change out a breaker either as long as you are aware.
 
Yeah, I'm pretty sure I should be able to swap breakers w/o killing the whole box, but I haven't read up enough on it just yet to feel comfortable. The first link I saw on the subject recommended killing the box, but I knew I didn't have enough time to do all the wiring I need to do this weekend, so I focused on just one circuit first (the exterior light that I wanted most). One step at a time.

I did get a chance to figure out some of the breakers--the PO made mistakes in labeling, but luckily it was done in pencil. Found the deck light is on the same breaker as kitchen and living room lights. Wife got to find out that all of the upstairs (including the a/c) is on the same breaker--flipped the wrong breaker at one point. Oops. Just two left that I know of to figure out.

Have to go get more screws for the breaker panel cover, managed to lose two of them.
 
Originally Posted By: supton
Err, it's been too long since college to figure out the RMS value on that waveform. I don't think it's that high actually, maybe 2Arms if I squint. If I get a chance later I'll have to go and "remember" how to do that bit of math.


I think you're over thinking it. It's basically two sine waves, add them together and they cancel out if both circuits are in use. Power factor is usually a minor issue in household wiring, it's the power company's problem. There's really nothing wrong with using 12/3 and getting two circuits out of it, except for the arc fault issue so they've kinda stopped doing that now.
 
No, I'd like to go back and figure it out--it's a shame to have paid all that for those courses, and then forget something as elemental as figuring out how to calculate RMS. I suspect just windowing the waveform into sections will do the trick, to find area under the curve. Easy peasy, just takes time.

Besides, I already did the fix. Removed the wire from the breaker, capped it off. Other end is capped off. Only thing odd is a 12/3 with a floating wire.
 
Doesn't sound legit...

Honestly if you don't know much about electrical, hire a pro. As Donald said, probably why the insulation on the romex is burnt. I don't know all the intricacies of code and it varies by location. Around here, I've never seen a multiple 1-phase circuits run off ganged breakers... sounds like a bad recipe.
 
"Code" is to conform to NEC, according to the town. Since I'm under a grand I don't need to pull a permit either. Plus, as outlined, it sounds quite legit, if not out of date.

I already stated why I thought the insulation was burnt: I think it got dropped onto a wood stove. It's 12g wire, after all. Maybe heavy load and being over a wood stove did it in? Dunno. Should know once I slice it open. Also, it wasn't ganged breakers; the breakers were separate (the one that is ganged is the water pump, which annoying is not ganged on the generator transfer switch).

Guess I need to read up on NEC. I found this but reviews indicate it lacks illustrations. I'll have to look later for something else, maybe there is a companion guide. I don't know much about electrical but I'd hope I could pick it up quickly enough.
 
It's a Multiwire Branch Circuit. You can Google for that.
Although you've capped off both ends of one wire (red?) you may find you have a room
or two that is wired to use it. And, who would do this kind of run, and not wire both hots?

If loads were balanced well neutral carries almost
no current. Now neutral is going to carry as much current as the hot carries.
 
True 240v only needs the two independent 120s and a ground. I worked on an electric dryer once that had the two hots, neutral and ground. The thing had a 120v motor and a 120v heater element. The neutral was there to take away the excess current from the uneven draws of the two.
 
Originally Posted By: SHOZ
True 240v only needs the two independent 120s and a ground. I worked on an electric dryer once that had the two hots, neutral and ground. The thing had a 120v motor and a 120v heater element. The neutral was there to take away the excess current from the uneven draws of the two.


You see them both ways, the older dryers typically just have 3 wires, two hot and and the ground, the new ones have 4 wires. When you buy the dryer, the guys who come to install it usually bring 2 sets of cords with them depending on what type of plug you have.
 
Originally Posted By: Wolf359
Originally Posted By: SHOZ
True 240v only needs the two independent 120s and a ground. I worked on an electric dryer once that had the two hots, neutral and ground. The thing had a 120v motor and a 120v heater element. The neutral was there to take away the excess current from the uneven draws of the two.


You see them both ways, the older dryers typically just have 3 wires, two hot and and the ground, the new ones have 4 wires. When you buy the dryer, the guys who come to install it usually bring 2 sets of cords with them depending on what type of plug you have.


In WWII they allowed stoves (and dryers, it seems) to run a combo neutral/ground to save copper for the war effort. This was successful enough it lasted into the 1990s version of code.
 
If it is a straight 240v load in the US, there is no need for a neutral. Say my well pump which is a 120/240v rated motor. When wired for 240v there is no neutral, when wired as 120v there is a need for the neutral. Ground is needed regardless.

Some ovens use 240v heater element but a 120v bulb so you need the neutral with that 240v circuit.
 
Originally Posted By: Joe_Power
FOR THE LOVE OF GOD- Do NOT listen to these shade tree electricians. It will get you hurt, or catch your house on fire. Drop some coin, and hire a PROFESSIONAL ELECTRICIAN look at it. You can thank me later.


Why? This is pretty simple stuff, really. I've just never done it before.

I just wish I had taken an electrical class in high school--sometimes I'm a bit weirded out by my education. Never took a class on how to balance my checkbook, but took three levels of calculus. Similar token, never took household wiring, but did small signal electronics and even a class on low power conversion (DC to DC convertors mostly). Never took a class on basic auto mechanics, nor carpentry. Sometimes I feel rather lacking...
 
If it was that simple, you wouldn't be asking on an internet forum... where peoples credentials aren't known. I'm lucky in that I have resources to ask and learn from... [censored], even our town inspector is very helpful. I did all the rough electrical, plumbing, HVAC in the house I bought and gutted.

When it came to electrical, between those resources and reading the NEC book I did alright.
 
Fair enough counterpoint. I'll counter with, with some simple explanation I'm off again. No pro required. The one odd circuit was explained, and it wasn't so odd after all.
 
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