How can I determine if my outlets can easily be grounded?

Question

I'm not sure what to do here. I just moved into a building and my outlets are all 2 prong outlets. Here is what I know of for sure:

• All the outlets are 2 prong outlets
• The bathroom outlet has the red/black reset/test switch. I'm guessing that means that the building is grounded?
• The building is off of power lines (not underground)

My fear is blowing my electronics. I am not sure what to do here to properly protect my electronics. I'm hoping that my outlets are grounded-ready or the such, but how can I know? What do I do here?

Answer 1

Depending on how old the building is, and when the wiring was done. You might be hosed, or really lucky. To find out which, you'll have to open up the box.

Start by turning off the breaker to the receptacle in question, and verify power is off with either a voltage tester or a non-contact type tester. Remove the receptacle cover, and undo the screws holding the receptacle in the box. Pull the receptacle out as far as you can, without damaging or disconnecting the wires from the receptacle. If there is a bare copper wire hanging around inside the box, you just hit the jackpot! Go out and buy a new receptacle (with ground), and hook it up.

If there is no ground wire in the box, You're basically done. There was a time when you could use the metal shielding of Type AC cable as a ground (if the building was wired with shielded cable), but I believe this is no longer acceptable in the eyes of the NEC.

Depending on the code adopted in your area, you may be able to replace the 2-prong outlets with GFCI receptacles. If you do this, you'll have to make sure you label the receptacles "No Equipment Ground" (a sticker should be included with the receptacle).

The best option at this point would be to call in an electrician, and have the circuits upgraded, or a new grounded circuit installed.

Answer 2

There are a few questions that need to be answered before an accurate answer can be given. Although the outlets only have two slots and no ground hole, you must determine if the metal boxes are grounded. During the 50's, BX cable was common and the spiral metal casing was often used to ground the boxes to the main panel. Often there was a small bare copper ground that was only connected to the box. you can test this with an ohm meter with the POWER OFF by checking from the neutral (white) to the metal box. A short means the box is grounded or tied to neutral. Conversely, and open or high impedance reading indicates no ground.

Never put a standard 3 prong outlet in a non-grounded circuit, however, in your case, a GFIC outlet can be used by attaching the green ground to the outlet box if the box is in fact grounded.