Electrical plugs and sockets have changed significantly over the years. Here is our guide to older style plugs, where you might find them, and what safety advances the newer style of sockets and plugs offer to homeowners.
In homes with smaller electrical services, say, 60 amps or less, homes with knob & tube wiring, or homes that have been updated from these situations we often find that they may also have ungrounded receptacles in the home as well. This includes two (2) prong receptacles and three (3) prong receptacles. This can be a potentially dangerous situation.
Two (2) prong receptacles were not designed for a ground and the three (3) prong receptacles have often been used to replace former two (2) prong receptacles. The result is that the three (3) prong receptacle then becomes ungrounded as it was not originally designed or wired with a ground wire. The only way to have these receptacles grounded then is to run new wiring from the main distribution panel to the three (3) prong receptacle.
For personal safety, we recommend that these ungrounded receptacles only be used with appliances / devices requiring same, for example, a lamp having a two (2) prong plug. Further, we recommend that all devices and / or appliances with three (3) prong plugs or polarized plugs be used only in conjunction with grounded three (3) prong receptacles and / or ground fault (GFI) receptacles. Do not remove grounding pins on three (3) plugs, as this is an electrical shock hazard.
You’ve probably noticed that plugs often have one prong that is wider that the other. This is done so that it can be properly aligned in a receptacle. The smaller narrower pin is for the “hot” black wire and the larger wider one is for the “neutral” white wire. This is very important when it comes to wiring new appliance plugs or receptacles as it assures that the current flow is proper through that device. Of particular note are certain devices or appliances that have circuitry, such as, coffee makers, alarm clocks, computers, etc. If the hot and neutral wires are reversed, damage can occur to these appliances. Do not “clip” the larger prong on a polarized plug to make it fit into a two (2) prong receptacle or a receptacle not designed for polarized plugs.
If you have any questions about electrical plugs and sockets, further professional advice from a licensed electrician is recommended.