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I was swapping some two prong outlets out for three prong grounded outlets in one of my rooms.

One of the outlets was kind of odd. On top it had a black (hot) and white (neutral) wire as I expected.

On the bottom however it had two black wires that were coming out of a thicker wire. Has anyone seen this before? I didn't know what it was so I just wrapped the two black wires with electrical tape and didn't connect them.

Since it was a two hole outlet ot begin with, I doubt it was a 240 wired into it. What type of cabling is it? Meaning, is it the old fiber wrapped wires? Old wires tend to both look black.

One thing I just noticed, this outlet is on the room wall against the hallway. On the hall wall directly across from it is another outlet. Would this have any bearing on this?

Edit: And I just confirmed, that outlet has no power. Could the two blacks be using this outlet as sort of a circuit breaker for that hallway outlet?

I am guessing here but it seems the wires you have tied in are the hot and return wires into the replaced outlet and the other two black wires are the runners to the other outlet. My suggestion, if you have room in the box behind your replaced outlet is to pull the outlet out, tie the wires together as they were connected before and run a pigtail to the outlet. What I mean is, take the hot off and wrap it together with the other black runner wire that was on the same side along with a 6" piece of spare wire the same size and wirenut them together. Do the same with the return wires and then run the pigtails to the outlet. If that's not an option, then you can run the wires as they were before on both screws, just keep them on the same sides as before. If you are going to do this in this fashion, wrap some electrical tape around the outlet covering the screws (it'll make somewhat of a cuff around the back of the outlet).

As always, cut the power first... I have to say it even though its common.

If the bridging link is broken between top and bottom, the bottom outlet may be a switched outlet that goes to a wall switch somewhere.

If your house is not wired in conduit, just "replacing" 2 prong outlets with 3 prong is not the best idea. You really need to replace the wiring in the walls as well with newer 2 conductor + ground wiring.

If the entire house is conduit (very rare) then you are getting a path to ground for the ground prong through the conduit itself. It is not as ideal as having a ground wire run the whole way, but it works.

EDIT: Also, if you are not sure about what you find when working with electrical, especially in an older house with different wiring standards: Do nothing and consult a licensed electrician. You have a greater risk of creating conditions where your house could burn down messing with electrical than any other system in the house.

It's not wired in conduit. I need to get an electrician to properly do it all but it'll be awhile before I can afford it. 6 months to a year I'd guess. For now this will have to do.

Well, the way it worked was something like this:

Black - Outlet - White
Black 2 - Outlet - Black 3

Now, the 2 outlets are like this.

Outlet 1 /Wall / Outlet 2

Directly across the wall from each other. One on each side of the wall. I was wondering if it is something like this wiring-wise.

Black goes to bronze pole on outlet 1. Black goes from silver pole on outlet 1 to bronze pole on outlet 2. So basically outlet 1 is acting like a kind of bridge or something for the power to outlet 2. But it seems like an odd way to do it.

I am not an electrician - just to get that out there, however I have done wiring myself and had my buddy who is a journeyman come over and check my work for a couple beers and a burger. What you are describing sounds dangerous. Brass screws are for the hots only while the silvers are for the returns only.

If you can work in the space without doing too much damage, I'd say grab 10 or 25 ft of 12/2 gauge wire (the ground is silent  :awesome_for_real:) from a hardware store (whatever small lengths they sell) and break that mess down to just the main supply wires and ditch the rest of the wires and clean out the boxes. Then run your pigtails with your new wire to the outlets in the proper sequence and if you are really leary about it, have an electrician come over and inspect it.

What in essence you should be going for is the main supply/return leading into the first outlet. Take a length of cable long enough to the other outlet and lead it over to the outlet with the supply/return cable. Strip off the sheeting on 8" of fresh wire and tie the black of that to the hot and the other black leading back to the other outlet. Wire nut all three together and connect that "bare" black wire to the brass screw of the outlet you are working on. Do the same with the returns (whites) only to the silver screw. Then wire up the other outlet with the runner you lead from the main supply/return cable. The ground wires are the wild card. I lived in an older house with 12/2 MC cabling throughout. Most of the outlets and switches are not grounded or grounded into the box. I asked both electricians I know and they simply say that is the way it was done per the code at the time. Scary to think about it, but that's how things fall sometimes. I got a pass using self-grounding outlets which basically tie back into the box. It works, but its not the best choice.

At this point I'm thinking of going to the hardware store and just putting some wirenuts on those extra black wires and hoping I can save up enough for an electrician to come out and properly ground the outlets I care about. (living room and computer room). Problem is i have no idea what that would cost.

Depending on your area, couple hundred bucks to wire up and entire room is not out of the ordinary. From what I have done, fishing line through walls and opening other parts of the walls is cumbersome. Luckily the remodel I did in the basement of the house I used to live at was as easy as it gets with opened walls and exposed studs. I doubt you want to re-drywall so it's prolly best to pay the piper. Just get an estimate first from at least three different contractors and mention what other guys are offering.

As for those extra wires, electrical tape on the ends is all you need since they are not part of a circuit. They are dead leads so there should not be any issue. You could grab a voltmeter and test them if you want, but from what you described, the power was coming in and branching to those. Once those are disconnected, they will always be dead till you do something with them. Good luck.

http://www.amazon.com/50957-Tester-Installation-Operation-110-125V/dp/B002LZTKIU/ref=sr_1_2?ie=UTF8&qid=1286895713&sr=8-2 (http://www.amazon.com/50957-Tester-Installation-Operation-110-125V/dp/B002LZTKIU/ref=sr_1_2?ie=UTF8&qid=1286895713&sr=8-2)
Buy this.

Putting in a 3 prong from a 2 prong isn't really a good idea, when you go to sell, a good inspector will use one of these on every outlet and then require you to get it fixed prior to sale. (The reason it isn't a good idea is you don't magically get a ground when you put it in).

How short of a run is it from the one outlet to the other?
It's also possible you have knob and tube wiring in some of your house and that's why both wires are black.

http://www.amazon.com/Fluke-1AC-A1-II-Volt-Alert-Non-Contact-Voltage/dp/B000EJ332O/ref=pd_bxgy_hi_text_b (http://www.amazon.com/Fluke-1AC-A1-II-Volt-Alert-Non-Contact-Voltage/dp/B000EJ332O/ref=pd_bxgy_hi_text_b) Also can buy one of these and tell which wire is the hot one.

The doohickey Furi linked initially is the first thing a homeowner should buy!

I use redundant voltage testers and also a multimeter. But I'm paranoid.

I'm going with puberty.

Was it wrapped in electrical tape? Have you plugged in a lamp on the other side?  They might have used whatever to bridge across.

Yeah, about the only thing they actually *do* with the electrical in a pre-sale inspection is look at the breaker box and stick a tester in all the outlets, having a three-prong outlet with no ground is asking for trouble.  If the circuit doesn't have a GFCI (by the age, almost certainly not unless it's shared with a bathroom that has been updated), you can jumper (short piece of wire) from the neutral to the ground screw (ground and neutral actually are linked in the junction box, so you're not creating a new hazard).

Within code?  Technically not, but no house that old is going to be anywhere near NEC-compliant, except as grandfathered.

--Dave

EDIT: Should have seen the nastiness I had to deal with for my house in Chattanooga, the original wiring was from the 20's, and some of it was still in use.  One circuit scared me so bad I not only disconnected it, I spackled over the boxes for it.  Stuff was *charred*.

Sounds like our house in longbeach, electrical was added after the house was built.

So, I'd get a short piece of wire, connect it to that little ground screw in my three prong outlet and then just connect it to the silver neutral screw and it'd make a sort of improvised ground?

Edit: And I just checked. This house was built in 1957

Geezus do NOT do this. It will work to fool those ground tester devices but you are creating a very bad thing. In essence, anything you plug into that socket is going to be energized from the return wire. If the device is metal or has some piece of conductive material, the device will just wait for a ground to become active, i.e. whoever the hell touches it and grounds the equipment. It does not matter if they both terminate at the source,  it's the travel part that is the concern - as the electricity will try and find its way back to source or ground along whatever path happens to complete the circuit. Please, google jumping ground to neutral or return screw and I am sure you will get some huge red flags from electricians.

Well, I broke down and called an electrician. They have an A rating with the BBB and tell you the exact costs up front once they look things over. They are also willing to finance.

Ok. They just left. I have a circuit box made by Federal Pacific Electric. Apparently they are considered a fire hazard so not only am I getting new grounded outlets, I'm paying for a new circuit box. I looked up the FPE box on the internet and it does have a bad rap. Apparently the breakers do bad things especially as they age so he wasn't blowing smoke about that. He looked at the mystery wires too and told me that that is an old way of doing things and with them disconnected some other outlet(s) probably don't have power.

Sorry to hear it man. That will be an expense, but in the long run you will be a hell of a lot safer. Sometimes shit like that, well there is no easy work around and you gotta pay the toll. This is one of those things you chalk up to investing in your own welfare and upgrading the house considerably.

Good deal. While teh old wiring thing was sketchy, those FPE boxes are bad business and you wouldn't have caught that one.

Well found out about that outlet today. It was providing power to the halloutlet. Oh, and it wasn't electrical wire. Not in the traditional sense. It was lamp wire. That's why it made no sense to me. They took it out and replaced it with real wires.

Well, you're technically correct, but only if you make a path to true ground that is lower-resistance than the neutral wire running back to the box.  Like one foot in the bathtub and a hand on the plugged-in appliance (which is why NEC now requires GFCI's on bathroom and kitchen circuits).

--Dave

EDIT: I might add, plugging *anything* into a two-prong outlet, with or without an adapter (assuming the adapter isn't grounded like it says to on the box but nobody does) will have exactly the same effect.  It's no more dangerous than the original outlet.

Yea - I had one of their boxes and replaced it as well. They allegedly have an issue with the double pulls if one side trips, then the circuit will never trip. So yea - good thing to fix probably.