Calling for the advice from electricians and at-home DIY'ers...

[Jayce]

Well, we're in. Friday was the move day and we've somehow managed to get several rooms furnished and things organized. Looking around the living room I noticed everything was 2 prong except one outlet. The home inspector informed me a lot of houses are equipped with 2 prong yet have a ground wire inside the actual box that's unused that I can utilize as a ground. Last night I took a few boxes apart, here's what I found:

Living Room - 3 prong box with two outlets - I can see 2 white wires on one side, 2 black wires on the other. There is also an exposed copper wire connected to a terminal at the bottom of the outlet as well.
Living Room - 2 prong box with two outlets - 1 white, 1 black, 1 exposed copper wire.
Kitchen - 3 prong box with two outlets - 2 white wires, 2 black wires, 1 exposed copper wire.
Bathroom - 3 prong box (one of those failsafe water-type ones with test/reset buttons) - 1 black wire, 1 white wire, 1 copper wire.

I'm curious if anybody can fill in some gaps. I thought I was just looking for a ground wire, but I'm confused over why some boxes have 2 black 2 white and others have 1 black 1 white, yet ALL of them are 2 outlet boxes, not 4.

In order for me to effectively wire up everything in a 3 prong grounded fashion, I of course need the ground, which I'm hoping is the copper wire I've referred to above. I assume the exposed copper wire is the magic ticket? Likewise, do I have to worry about the number of black or white wires in the box?

 

[S0ULphIRE]

Your 3 point systems are power, neutral, and ground. The third prong is basically a safety addition, but it's not needed. You *should* have it, but yeah it'll work without.

Neutral and Ground connect to the same point.
Neutral is for completing a normal circuit between power and the load (i.e Power > Toaster > Neutral)

Ground is for grounding the appliance in use, in case it becomes live. For example, something breaks somewhere on your toaster and suddenly the outside casing is connected to a current source. In a two-point system if you then touched it you'd ground that current through your body, and be crispy.
BUT in a three-point system, the extra ground point would be connected to the toaster's exterior by design, thereby grounding it and saving you. It'll trip the power box straight away (or blow the fuse) but you'll be alive

As for the number of wires attached, could be just that the power sockets are being connected together at the sockets themselves instead of further back in the wall. No worries there.

NOTE: *DISCLAIMER* not a professional electrician, if you die by following this advice then turn-around-touch-the-ground-can't-sue-me, etc et al

 

[Crysalis]

White leads are positive, black are negative and the exposed copper are the grounds. The number of black/white does not matter... just hook them up properly and usually on the back of the outlet there is a greenish/blueish screw designated for the ground (the exposed wire). Shut the breaker off... hook it up. Turn breaker on. Sparks fly, shut it off. Sparks dont fly, plug something in that you dont value. If it works... hoorah!

If you can build a PC, you can wire a house.

Edit: Forgot to mention... the reason multiple black/white wires are there are to likely daisy chain to another outlet or lighting fixture.

 

[Jayce]

White leads are positive, black are negative and the exposed copper are the grounds. The number of black/white does not matter... just hook them up properly and usually on the back of the outlet there is a greenish/blueish screw designated for the ground (the exposed wire). Shut the breaker off... hook it up. Turn breaker on. Sparks fly, shut it off. Sparks dont fly, plug something in that you dont value. If it works... hoorah!

If you can build a PC, you can wire a house.

Edit: Forgot to mention... the reason multiple black/white wires are there are to likely daisy chain to another outlet or lighting fixture.

Ahh okay, that makes sense. I know in this house some light switches control outlets so you can have area lights be controlled by the switch, so I got to thinking maybe the extra wires are going to the light switch, etc. However when I flipped the switch the other night, the TV didn't shut off that was plugged in, so that kind of nuked that thought process that maybe the extra wires was to the light switch.

So moral of the story is this, if I'm seeing a black, white, and copper wire, I have a 3 point system and I CAN effectively change all of the outlets without changing the wiring and convert over to 3 prong?

I'm confident with wiring, and I've built hundreds of PCs so I guess we're in good shape there! I just haven't done it in SO long I was surprised how "derp derp" I felt when I took the socket off and realized, wow, did I really forget how to do this??

 

[Crysalis]

Yep - if you've got all three, you're good to go. You're correct about the switch... and it is probably only wired to one socket so you can have one switched and one non-switched with a 2-socket outlet.

 

[Jayce]

While we're on the topic (it sounds like you've done this many times before) do you have any idea when 3 prong outlets became standard? This house was built in '58 and we're the 2nd owners, but during our house search we looked at houses as old as 1890's, etc. I'm now wondering what kind of electrical differences there are from 1890 to 1958 to 2012, etc. Are new houses being wired up with the same black/white/exposed copper as I'm seeing in mine?

I guess the bottom line is, with having a ground wire there, I fail to see why they wouldn't have just put 2 prong outlets in anyway. I mean some of these boxes... the ground is just curled up and sitting in the back. Why not use it? Is it possible 3 prong outlets were just THAT pricey that it was a means to keep costs down?

 

[Crysalis]

I have no idea when they became standard... probably 70-80's? It sounds to me like the first owners need to do electrical upgrades probably for newer appliances or even safety concerns. New homes are wired with the same 3 leads. Now that I think of it, your house may have originally been wired with 3-leads for future proof reasons and since nothing used the ground back then, they didn't bother using the then expensive 3 prong outlets. My grandmothers house was built in the early fifties and it has the 3 leads, but all of her outlets are 2 prong. I think the 50's was probably around the time they stopped doing the "knob and tube" wiring or whatever they called it... used to just wrap a positive and neutral lead around a pole you hammered into a stud. No conduit or real protection. Conduit became standard and now the 3 leads are usually wrapped together.

(don't quote me on this stuff... I just spent MANY MANY days wiring houses with my father when I was a kid)

 

[Crysalis]

Looks like it was the 50's that 3-wire became standard, but not necessarily the outlets. Now i have something to read at work!

 

[Jayce]

Haha sounds good. Thanks for the info!

 

[C0RR0SIVE]

If you can, upgrade to 3 prong, just kill power and swap the wire to the new outlet. It really can be a safety issue, ever touch two computer cases on two different circuits that are not grounded? You actually usually get a NASTY little shock sensation going through you. Ground is meant to bring every thing to a common charge and literally allow excess power go straight into the ground.

Be thankful your home uses copper wiring, at one time they used ALUMINUM wiring, talk about dangerous. House wiring in the early 1900's, and if the ower was insainly lucky, late 1800s used ceramic knobs and bare wire, each wire was a foot apart, and ran along where ever to get power, all it was used for in those days was a light bulb or two, and if you was rich enough a radio that used them fancy wax like capacitors.