Upgrading Outlets

I am a little confused about whether or not you can uprgrade a two-prong polar electrical outlet to a three-prong outlet? Someone please help me understand if I can do this, and how I would go about doing it. I live in an old (built in the 40's) apartment right now, so I can't rip the walls apart or anything, but I would like to change the outlet to accomodate my computer power strip if possible. Thank you!

 

if it has a metal box, you can. you just need to ground the outlet to the box( with green screw). and you will be all set.

 

Being it is an apartment you will need your landlords permission before doing this.
There are a few methods of solving your problem replace the receptacle with a GFCI receptacle, putting the sticker on it that there is no ground and use it.
Another method would require that the boxes were metal and metal clad cable was run to them in which case the cable can be the ground and all you would have to do is connect a green ground wire from the grounding screw of the receptacle to the box. Again this only works if the cable feeding the box is Armour Clad and the box is metal.
The third option is to by a three prong to two prong adapter and use it. Not a good solution but if used in conjection with a surge protected power bar can work

 

Gard is correct -- a metal box is not necessarily grounded.

 

The GFCI option will provide no protection for your computer. The only solution to protect your computer (other than a connection to a metal box that you have verified to be grounded), is to run a grounding wire (or a whole new cable) from this outlet back to the grounding bar in your panel. It's not necessarily easy, but millions have done it before you.

 

How would I go about verifying that the box is grounded?

 

About the best you can do is measure for voltage between the black wire and the box. If you get 120 volts, assume that the box is grounded. It not a certain test, but a better test would require expensive equipment.

 

A relatively certain test would be to use a light bulb and socket to test black to box.

 

A surge protector is usless of you do not have a ground. A surge protector works by shunting surge voltages to ground. If you have no ground then you have no protection

 

You could put surge protection at the panel too. Sometimes I think it might be a better idea to put the puter on gfci, and not ground it. The only thing that gets struck at my place is the puter,, thru the phone line. Other phones dont seem to have a problem, just the computer which is grounded. I dont think my phone company has been grounding their stuff right.

 

Gary, the reaon I say it is not certain is because of the possibility of a hidden bootleg ground (interconnected grounded and grounding wires). But your suggested test is a bit more certain than mine -- it helps weed out really bad grounds.

 

Surge protection isn't the only reason you ground office equipment, there is EMI/RFI supression at stake also.

 

Take a lamp and plug it into this receptical and turn the lamp on, go to your breaker panel and turn off only the single tab breakers NOT and that are tied together, once your lamp is off, remove the cover and take a look at the sides of this receptical.

Are there 3 wires that come to this if not you need to determine if your recpetical box is screwed into metal studs in the wall. If they are then good if not then you have no way to ground your receptical unless you can get a ground wire that is close to where the main wires come into this receptical and pull a ground to this box.

When you terminate a wire to a receptical NEVER use the holes on the back of a receptical, always WRAP your wire SECURELY around the terminating screws of the appliance that you are connecting to.

Black wire to gold, white wire to silver, ground to green.

 

why do you say not to use the holes on the back?

 

Because those holes in the back, called backstab connections, have a high failure rate. And they don't make a very good connection even before they fail.

 

John
If you keep giving sound advice like that you are really going to cut into the service call income of electricians such as my self (is this the right emoticon for tongue firmly in cheek?). How am I supposed to make extra money for Christmas presents if you discourage people from using the junk and encourage them to use good technique.

I had a three hour service call today to locate one of those push in receptacle connections that had gone bad. The receptacle with the bad connection still worked fine but the rest of the circuit on another floor of the home had an open neutral because of the faulty push in connection.

There is a type of back wired receptacle that is very reliable. The ones with two wire entry holes per terminal that you have to tighten the screw to clamp the conductor between two metal plates work really well and make a quality connection.

So go ahead and use the good stuff because there will still be a lot of people out there who's homes will have been wired by contractors (subsidiaries of nocturnal aviation ) who believe that any contact that outlast the one year warranty is fine with them.
--
Tom