Electrical wiring question

[Black88GTA]

I just moved into a new house, and my room only has two sets of outlets in it - and both are two prong only . I want to replace them. I found a little guide here biut it's for the 3 prong ones. I did some reading elsewhere and found that the center screw between the two outlets can also be used for ground.

So, I tried checking the voltage on my outlets with my multimeter....but got different results on each one. Here's what I have so far...

Outlet 1:
123v between both prongs on both outlets, 19v between center screw and small prong (hot) on each.

Outlet 2:
123v between both prongs on both outlets, 123v between center screw and small prong on each.

What's going on? Is the 2nd outlet grounded and the first one not? or is something wired improperly? Anyone know?

 

[Malfeas]

Its easy. There is one 'Hot', one neutral, and one ground. Neutral and ground are the same. Jumper neutral and ground together.

 

[Black88GTA]

Originally posted by: Malfeas
Its easy. There is one 'Hot', one neutral, and one ground. Neutral and ground are the same. Jumper neutral and ground together.

I'm not sure it's that simple...otherwise, why would there be the 3rd prong at all? If they truly do serve the same purpose, then they would be redundant....

 

[drinkmorejava]

Well, if you want to replace the socket. Just take the faceplate and outlet off, hook the white and black up how they are [on a new three prong outlet], and you should have a third, paper insulated wire, that you would attach as the ground.

 

[Malfeas]

Fine, 8 years as an electrician and 2 years as a power dispatcher for an electrical utility means I don't know anything.

The purpose for the third 'Ground' prong is because it is usually attached to the case of an electrical appliance. For example, an electric drill. Lets say that the drill becames shorted, in order to prevent you from recieving an electrical shock when you pick up the drill, the case of the drill is grounded. Hence the third prong.

 

[jagec]

Originally posted by: Black88GTA
I'm not sure it's that simple...otherwise, why would there be the 3rd prong at all? If they truly do serve the same purpose, then they would be redundant....

As far as a home user is concerned, they are. They are both 0v potential lines. The difference is that the ground wire is supposed to connect to a ground in your house, whereas the cold wire goes up to the power lines. However, the power company hates you if you just use hot->ground for all your outlets, since it's hell on their generators if everyone does it. (Malfeas, correct me on this...)

 

[Black88GTA]

Originally posted by: drinkmorejava
Well, if you want to replace the socket. Just take the faceplate and outlet off, hook the white and black up how they are [on a new three prong outlet], and you should have a third, paper insulated wire, that you would attach as the ground.

right...but I'm trying to figure out if the junction boxes are grounded in the first place. I want to make sure they are wired up right before plugging expensive stuff into them. The fact that I got two different results when I checked them with my meter kind of worries me - I want to know which one of these outlets is "good" and which isn't (or if neither of them are).

 

[Benthere]

It could be either,did you check outlet 1 from the neutral side to the screw? If it measures 120 volts then its wired wrong,if not then its not grounded.You can change the recepticle or you can buy an adapter that will convert it to a 3 prong outlet. I would turn off the breaker and remove the outlet. If you have a black,white and a bare wire,I would change the outlet. Black is Hot,White is neutral and bare is the ground.

 

[Black88GTA]

Originally posted by: Malfeas
Fine, 8 years as an electrician and 2 years as a power dispatcher for an electrical utility means I don't know anything.

I'm not trying to step on anyones toes, I'm sorry if I offended you. I didn't mean for it to sound that way. If that's the way it is, then OK...I readily admit that I know nothing about household wiring.

I just didn't see the point of the 3rd prong, if the function of both was exactly the same.

Originally posted by: jagec

As far as a home user is concerned, they are. They are both 0v potential lines. The difference is that the ground wire is supposed to connect to a ground in your house, whereas the cold wire goes up to the power lines. However, the power company hates you if you just use hot->ground for all your outlets, since it's hell on their generators if everyone does it. (Malfeas, correct me on this...)

Hmm...so you guys seem to be in agreement...I might just do that then. Do you guys know any possible reasons for why my two outlets are giving different readings on the multimeter?

 

[jagec]

Originally posted by: Black88GTA
Outlet 1:
123v between both prongs on both outlets, 19v between center screw and small prong (hot) on each.

Outlet 2:
123v between both prongs on both outlets, 123v between center screw and small prong on each.

What's going on? Is the 2nd outlet grounded and the first one not? or is something wired improperly? Anyone know?

Make or buy a tester. There should be three lights on it, one for hot->ground (yellow), one for hot->cold (yellow), one for cold->ground (red)
If it's wired correctly, the two yellows will come on, and nothing else.
If the hot is disconnected, no lights will come on.
If the cold is disconnected, the first yellow will come on.
If the ground is disconnected, the second yellow will come on.
if the hot and cold are reversed, the red and second yellow will come on,
and if the hot and ground are reversed, the red and first yellow will come on.

If one of the lights comes on dimly, there must be current leakage somewhere. Find out where, and deal with it.

ah, found a pic of one.

 

[Black88GTA]

Originally posted by: Benthere
It could be either,did you check outlet 1 from the neutral side to the screw? If it measures 120 volts then its wired wrong,if not then its not grounded.You can change the recepticle or you can buy an adapter that will convert it to a 3 prong outlet. I would turn off the breaker and remove the outlet. If you have a black,white and a bare wire,I would change the outlet. Black is Hot,White is neutral and bare is the ground.

I just checked it...neutral side to screw on outlet 1 is right around 5 volts. The same measurement on outlet 2 is <400 mV (it bounces around a lot).

 

[Malfeas]

Usually, you have two hot wires and one neutral from the power company coming into your house. At your main breaker panel, the neutral is also connected to the houses ground rod. If you follow the three wires from your outlet to the main breaker panel, you will find that the neutral and ground go to the same connection in the breaker panel.

 

[Black88GTA]

Originally posted by: jagec

Originally posted by: Black88GTA
Outlet 1:
123v between both prongs on both outlets, 19v between center screw and small prong (hot) on each.

Outlet 2:
123v between both prongs on both outlets, 123v between center screw and small prong on each.

What's going on? Is the 2nd outlet grounded and the first one not? or is something wired improperly? Anyone know?

Make or buy a tester. There should be three lights on it, one for hot->ground (yellow), one for hot->cold (yellow), one for cold->ground (red)
If it's wired correctly, the two yellows will come on, and nothing else.
If the hot is disconnected, no lights will come on.
If the cold is disconnected, the first yellow will come on.
If the ground is disconnected, the second yellow will come on.
if the hot and cold are reversed, the red and second yellow will come on,
and if the hot and ground are reversed, the red and first yellow will come on.

If one of the lights comes on dimly, there must be current leakage somewhere. Find out where, and deal with it.

I'll probably get a tester when I go to Home Depot to pick up the new outlets Probably a good thing to have anyway. I'm thinking (with my very limited knowledge of AC current) there's something wrong with outlet 1...

 

[Squisher]

The easiest way to get a ground is to install GFCI outlets, but install the little stickers on it that say, "no mechanical ground."

Otherwise, you'll have to run wire.

 

[BigJ]

Originally posted by: Squisher
The easiest way to get a ground is to install GFCI outlets, but install the little stickers on it that say, "no mechanical ground."

Otherwise, you'll have to run wire.

Expensive though.