How to upgrade a two wire outlet to a safe 3 wire outlet for less than ten dollars
Replacing a 2 prong outlet with a 3 prong GFCI outlet greatly improves the safety of an ungrounded electrical system15-30 minutes - it will probably take almost as long to read this article as it will to do the job.
Subjects in this article are covered by the National Electric Code - NEC 2005 section 406.3(D)(b),(c)
Have you ever had to use an adaptor in order to plug an appliance or tool into an old 2 wire non-polarized outlet? Or even worse, have you ever used a tool that was missing the grounding prong because someone had hacked it off in order to use a two wire outlet? Or worse yet, has someone installed regular three wire outlets into your 2 wire system, thus allowing grounded appliances to be plugged in while giving a false sense of security? All of these situations are potentially life threatening, and should be corrected. Many houses which were built before 1941 still have two wire electrical systems, which can't safely accommodate many modern appliances. If your home is in this category, then there is a safe, economical way for you to upgrade your outlets to a three wire system, by installing Ground Fault Circuit Interrupter outlets (commonly called GFI or GFCI receptacles).
The third wire of a three wire system is designed primarily to protect people from being shocked. It accomplishes this by providing a path for the current which is caused by a "Ground Fault" (also known as a "short") to go to "ground". If the current is at all substantial, this will cause the breaker to trip (or the fuse to blow), preventing the faulty equipment from being used, and thus protecting the user from being shocked. Nothing is completely fool proof though, and one of the shortcomings of a regular grounded system is that there could be a ground fault without sufficient current to trip the breaker, but would still allow a person to be shocked under certain circumstances, especially if the person is a better path to ground than the system ground (if you were standing in water for example).
A GFI device actually provides better protection than a grounded 3 wire system does, but in a different way. The GFCI electronically detects even a very small ground fault and very quickly interrupts the current to the device. This provides protection even if you are standing in water, that is if everything is working correctly, but don't tempt fate by unnecessarily gambling on technology. Never use electricity when you are standing on wet ground.
Warning: Some appliances, such as microwave ovens can hold a high voltage charge on internal parts (like a capacitor) which could conceivably energize the appliance frame, so you should not rely on a GFCI connected to a two wire system to safely power a microwave oven. You should have an actual grounded receptacle installed by a qualified person instead.
Note: Even though a GFIC receptacle will be able to accommodate grounded 3 wire plugs, and will usually protect people from shocks due to ground faults it still won't actually be grounded if installed on a two wire system. Because of this fact certain devices won't work correctly if plugged into such an outlet - especially surge suppressors which work by directing excess current to ground. So, don't plug delicate electronics into a GFIC outlet that is connected to a 2 wire systems. Surge suppressors and delicate electronics need an actual ground!
Replacing a two wire outlet with a three wire GFI receptacle is a safe, easy do it yourself upgrade that will make your home safer and more convenient.
Disclaimer: I am not a codes official. I am also not an expert on electrical wiring. This web page is strictly for entertainment purposes. If you choose to do wiring work of any kind then you and you alone are responsible for learning what the code requires, and applying the code to your work. NoJolt and its associates shall not be held liable for any loss of life, limb, or assets caused by the application or misapplication of this information. If you are going to do electrical wiring, you should educate yourself about the code. If you spot anything in this that you think is incorrect, please contact me at mailto:info@NoJolt.org
How To Do it!
What you will need:
1) GFCI receptacle and cover.
2) #2 Phillips screw driver
3) Medium slot screwdriver
4) Wire stripper
5) lineman's pliersYou might also need
A very small slot screw driver
2 red wire nuts
Short pieces (3-4 inches) of black and white copper house wire
Before you start - In most jurisdictions a codes inspection will not be required for a simple remove and replace procedure like this, but you should check with your local code authority (call your electric service provider) and get an inspection if it is required. It is possible that in some jurisdictions it is not legal for anyone except a licensed Electrician to perform something like this. It is also possible (even likely) that in the event that your home were to burn down because of defective work that you have done yourself, and not had inspected, that your homeowners insurance could be void. Find out before you proceed.
1) Turn off the electricity to the receptacle that you are replacing - DO NOT rely on the labels in the electrical panel. The easiest and most fool proof way to be sure that the power is off is to plug a radio or other noisy appliance into the receptacle in question and observe that it has gone off when you trip the breaker.
2) Remove the old cover and plug - try not to damage the wires while disconnecting them.
A) If the free amount of wire is more than 6 inches then you can simply cut the wires close to the receptacle.
B) If the wires are not longer than 6 inches then you should try to disconnect them without cutting them.
C) If the wires are connected to the receptacle with simple screw connections then the removal process is pretty obvious.
D) Some receptacles use a connection (now against most codes) where the wires just push into a hole on the receptacle and a barb keeps them from coming out. You can free the wires in this case by pushing a very small screwdriver into the small slot next to the wire hole, and thus depressing the barb and releasing the wire.
E) Yet another possibility is a setup similar to D) but instead of a barb the wires are retained (and released) by screws on the sides of the receptacle. Just loosen those screws and the wires come out.
3) Inspect the wires for damage, if you find damaged insulation, you can repair that by wrapping it in approved electrical tape. Note that all black vinyl tape is not necessarily approved for this purpose. If the conductors are damaged or are too short to work with, you might have to replace the cables, which would be outside of the scope of this article.
4) If you have only one black and one white wire, then they are the "Line" Voltage wires. Skip to step #6
5) If you have two black and two white wires then you will have to use a circuit tester to determine which are the "Line" and which are the "Load" wires. Once you have determined which is which and labeled the wires, proceed to step #6.
6) Strip about ½" of each wire taking care not to cut into or nick the conductor. Connect the black line voltage wire to the brass screw on the GFCI plug which is labeled "line"; connect the white wire to the silver/white screw that is also labeled "line". Connect the load wires (if any) to the screws labeled "Load". It may be possible for some GFCI receptacles to function (although not correctly) even if wired up backward (a condition known as Reversed Polarity) so take care that the black wire is connected to the brass screw and the white wire is connected to the white/silver screw. Note: One GFCI receptacle can protect other receptacles in the same circuit, and this is what you are accomplishing if you have connected the "load" wires as described. You may also replace the protected outlets with plain 3 prong outlets, but you must label all of them including the GFCI outlet "GFCI Protected" and "No Equipment Ground".
7) Many GFCI receptacles have connections like those in E) above, in which case you simply insert the stripped portion of wire into the appropriate hole and tighten the side screws. Others require that you form a hook on the end of the wire and tighten it under a screw, in which case take care that the hook goes around the screw in a clockwise direction, otherwise the screw might come loose during installation or use, causing an Arc Fault (AKA a loose connection). Make sure that all connections are tight by checking screws one last time with your screwdriver, and giving the wire a little tug. The number one cause of house fires is loose connections, so don't cut any corners here, and you might consider installing Arc Fault Breakers just to be safe. However, if you over tighten anything and you feel or hear something break, then throw the broken plug away, and get a new one.
8) After checking all connections, push the receptacle fully into position in the box before tightening the screws that hold it in.
9) Install the cover plate
10) Turn on the electricity
11) Push the "Test" button on the GFCI plug - if the "Reset" button pops out, then all is well. Otherwise, you have done something wrong. The most likely thing being that you connected the line voltage (AKA "hot") wires to the "load" instead of the "line" terminals. Any such problems must be corrected immediately.
12) Label all protected outlets including the GFCI outlet "GFCI Protected" and "No Equipment Ground". Be aware that when the GFCI is tripped, then all protected outlets will be disabled.
13) Be safe - make sure that you have smoke detectors and fire extinguishers, and an emergency plan for your family in case of fire.