Beware of faulty wiring!
I bought an old house twenty years ago. It was built in 1918, during a time when houses were wired using the “knob and tube” wiring system. My home inspector looked at my panel and saw only new wires leading into the panel. He observed that three pronged outlets were available throughout the house. Based on these observations, he concluded that my house had been rewired correctly.
Boy, was he wrong! The only outlets that were wired properly, were in my basement!
If I had known then, what I know now, I would have fired him and reported him to the home inspector society. His report had disclaimers saying that he cannot see through the wall, so the report is based only what he could see. That is fair. However- it does not take much to find out whether or not your outlets are wired properly. This inexpensive little gizmo on the right does it all. All you have to do is plug it in, see which lights go on and read the sticker.
Incorrectly wired outlets can go undetected for a long time because many loads/appliances aren’t sensitive to polarity – which means they operate quite well with the neutral and hot reversed. Some loads are indifferent to AC polarity – they may be table lamps or electronic loads that convert AC to DC. The prongs on the plugs for these loads are the same width, see the cell phone charger plug in the picture.
There are other loads/appliances that are not sensitive to polarity to operate, however they require the polarity load to be correct for safety reasons. For example your older toaster will be able operate under reverse polarity, however if you stick your knife in to clear an object while your toaster is off, you are in for a nasty shock! The wiring in the toaster will be live even with your taster off. (By the way – you should always unplug any appliance that you are trying to fix.) For a load where the polarity matters, one of the prongs on the plug is wider than the other so that it is restricted to connecting the correct way. See the white plug in the picture. Unfortunately your protection from shock is lost if your outlet is wired backwards.
There are other loads/appliances that require a clean ground meaning a connection with no load current or voltage. These are wired with the three-prong plug where the cylindrical prong is the ground. The ground wire attaches to the appliance casing rather than the electronics in the appliance. This system was developed to protect you from shock in the case that a short develops inside the appliance.
So what do you do if you find faulty wiring? I recommend that you start by tagging each outlet that you find is faulty. I like masking tape. Then you can asses the size of your problem, call your electrician with your list and take interim precautionary measures until your wiring fixed.
- Do not use three-prong plugs in outlets that are not properly grounded. (I would tape over the ground hole as an extra visual reminder.)
- Do not use outlets where the polarity is reversed for any loads where the load needs proper polarity to be safe (one prong in the plug is wider than the other).
- Do not use any outlet where the ground is hot!
Remember – having properly wired outlets is for your safety and the safety of everyone that lives or visits your home!