I've done some searching on this already and I think I know the answer. But I'd like to ask just to double check.

If i am not sure if the outlets are properly grounded, my best bet would be to replace the 2 prong outlets with GFCI outlets, correct? Actually, i suppose someone is going to say my best bet would be to first find out for sure if they are properly grounded or not :) Could someone suggest a relatively inexpensive tool for doing that?

If the boxes are correctly grounded, then I should be able to just replace the 2 prong outlets with regular 3 prong outlets, correct?

For right now, I mainly want to swap out a 2 prong outlet in the living room that the TV and the rest of the media/gaming stuff will be plugged in to. But there are 2 prong outlets scattered around the house that I'll probably also want to eventually replace.

I would be somewhat surprised if everything is correctly grounded since the wiring in the house is pretty old, it's all knob and tube wiring. Although the home inspector said it all looks like it's in pretty good shape. Eventually we'll have an electrician come in and replace all the wiring, but for now it's staying as is.

  • It's not likely a 70 year old house; especially one wired with knob and tube, has adequate grounding conductors. Unless; of course, the house was rewired at some point. – Tester101 Nov 12 '14 at 0:08

I would not put a 3-socket outlet on a 2-socket system, even though a lot of electricians do it. The neutral and ground are not the same thing. Neutral is part of the circuit and has electricity flowing through it. Ground does not have electricity flowing through it, unless there is a short. There is already a topic on why you should not connect the ground and the neutral.

If you think you can guarantee an earth ground, then hook it up and test it like this:

(1) hot and neutral CORRECT VOLTAGE

(2) hot and ground CORRECT VOLTAGE

(3) neutral and ground NO CONTINUITY

The outlet should pass all three tests. In other words if you put a connectivity tester on the neutral and ground sockets it should NOT beep. If you put the continuity tester between the neutral and the ground and it throws a huge spark and melts, then you just found out you did something wrong.

  • 2
    Unless you disconnect the circuit at the panel you will have continuity between ground and neutral - they are tied together at the main panel (and only at the main panel if installed properly). – Grant Nov 11 '14 at 22:55
  • If the neutral and ground socket are connected, and the path to ground of the neutral is disconnected for any reason, then what will happen is that ground socket will become electrified and the housing of any appliance connected to that socket will have a potentially lethal electrical charge. – Tyler Durden Nov 11 '14 at 23:06
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    Grant's point is that the neutral and ground are connected together, but only at the main breaker/fuse panel and thus, you will have continuity between neutral and ground. You are correct that they should not be connected together anywhere else, for the reason you mention. Unfortunately, without careful examination of the wiring or an expensive ground/neutral impedance tester, it's hard to tell where the connection is. I agree, without a complete re-wire of a K&T system to modern wiring, the best bet is to put in GFCI outlets with no connection to the ground pin. – DoxyLover Nov 11 '14 at 23:32
  • unless i'm using something that's likely to shock me, there's really no advantage to using the GFCI outlet versus just getting a 3 prong to 2 prong converter, is there? right now i'm just plugging in my entertainment equipment. So i think it's pretty unlikely i'll get shocked from a new tv or a ps4. Which if i understand the purpose of GFCI socket, means they wouldn't really give me any benefit over just using the 3prong to 2prong converter. – merk Nov 12 '14 at 11:14
  • @merk "unlikely" is a pretty lax criteria when talking about something that could potentially kill you or your loved ones, destroy your house, etc. – Grant Nov 21 '14 at 20:18

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