Wiring in an old home

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  #1  
Old 11-22-05, 09:55 AM
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Wiring in an old home

Hello, I live in a home about 70 years old.

I was replacing the wall outlets and switches since they are very old. When I take the old switch or outlet off there are just 2 wires - both black.

What do I hook these up to on the outlets and switches - one on each side? And does it matter which one? For the outlets, there are 4 screws, do I just need to hook it up to one on each side.

Thanks

Cary Sauer
Electrical newbie
 
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  #2  
Old 11-22-05, 11:07 AM
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For the new switches it does not matter, as long as you don't connect to the ground screw (usually green).

For the receptacles, you MUST use only two prong receptacles. Do not install three prong (grounded) receptacles, you will create a code violation and possibly lead to an unsafe situation.

On the receptacles you must connect the hot wires to the gold screws and the neutral (or return) wires to the silver screws. It makes no difference which screw you use. You should pay attention to which screw the wires came from on the old receptacle. If it's too late to pay attention to the old receptacle then you will have to buy a tester and determine which is the hot wire.

One other caution. if any of your receptacles were half switched and half always hot, then you will need get the wiring exactly as it was on the old receptacle, including the breaking off of the small tab that connects the two screws on the hot (and possibly, but not likely, also) the neutral side of the receptacle.
 
  #3  
Old 11-22-05, 05:04 PM
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My house is 58 years old, and I had the 2 wire BX (armored cable). At first, I thought both wires were black, since everything was so dirty. Upon closer inspection, you could see a little white on the cloth insulation of the neutral wires. I am in the process of rewiring the entire house to 12-2 WG Romex. You may want to consider the same.
 
  #4  
Old 11-23-05, 06:16 AM
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Thank you. I am replacing them with 2 prong outlets but do not know which one is hot - when I removed the old outlet both sides looked identical.

I have a yellow tester - do I just put the dial to ohm and touch the wire and the screw to find out which one is hot?

How hard is it to switch the house over to 12-2 wiring and could I do that as an amatuer or would it be better to get an electrician. Any idea on the cost - not too big of a house - 1800 sq feet, 3 stories though.

Thanks
 
  #5  
Old 11-23-05, 06:29 AM
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I do not know what you mean by yellow tester.

To determine which wire is the hot wire, you need to test for voltage on the wire.

You can use a voltage tick tester, which is a device that will "tick" or "chirp" or "beep" or whatever when you get the probe near a hot wire. You have to be careful, since all the wires are near each other it may be tough to figure out which is the hot wire.

You can use a voltmeter or a neon light tester. To do this you connect one probe to the wire to be tested, and the other end to a known good ground. You will probably need an extra wire for this. A known good ground is the neutral wire on a properly wired receptacle, a ground on a properly wired three wire circuit, or usually a metal water pipe in the house. You cannot test between unknown wires on the circuit in question since the tester will work if you get the wires backwards.

When you are done replacing a receptacle, check it with a good quality plug in tester. The plug in tester will have three prongs, so use it with a three to two prong adapter. It will tell you open ground, but it should test okay otherwise.


Replacing wiring is a time consuming project, and time accounts for a good deal of the cost. It is easiest if the house has an unfinished basement and attic. It may mean damaging the walls or ceiling somewhat. It is not particularly difficult, but you need to know the rules regarding where and how wires can be run. This will likely cost you in the thousands of dollars to have an electrician do this.
 
  #6  
Old 11-23-05, 05:59 PM
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Cary, here's an idea for you to file away in case you rewire your house yourself and it's also an example of how hiring an electrician can be well worth the money.

My house is 100 years-old and each bedroom had just one outlet. I hired an electrician to add at least one more outlet in each room. But there was a problem in the room that serves as my office. There was no easy way to run a new wire to it. My walls are plaster -- probably yours too -- and the cavity is filled with lathing, old-fashioned sawdust insulation and who knows what else.

I was stumped but the electrician had an easy remedy. He attached a conduit to the outside wall of the house and used it to run a wire from the basement up to the second floor and into my office. Since I have several pieces of computer equipment, he split the new outlet between 2 dedicated circuits.

This is no doubt no big deal for many of the posters in this forum, but neither idea had occurred to me.

Oh, I forgot to add that the electrician and his partner did this job and a bunch of other stuff in less than three hours.
 
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