On one of my home inspections yesterday, I had the distinct feeling that I knew the contractor who had worked on the home. Certain mistakes become signatures, but I know that a few things will pop up with many who do similar work. In the case of the home, it was making the electrical system meet the needs of today’s homeowners, without actually doing so.
Today’s appliances liked to be grounded. The third prong is a safety feature to help prevent electrical shocks. My nice older home, built in the sixties, frustrates my wife with only having two prong outlets. A solution which is taken by homeowners and contractors is to replace the older two prong outlet with a three prong. The problem occurs that to a new owner there is the perception that they have a grounded receptacle. The home had no wiring for the ground, so no wiring for the grounds exists in these outlets. Yesterday’s home had a twist though. A sub-panel ( a breaker box which serves as an aid to the main panel from which it gets its power) had been installed at one point in the seventies. At that time, ground wiring was ran through to the bathrooms and kitchen.
A common mistake is switching the hot and neutral wires. Most new receptacles will have a marking indicating where the black (hot) wire should go and where the white (neutral) wire should go. Screws will be painted white or black, or there may be an imprint. As a last resort, you will have to read the dreaded instructions. It is only one page, so do not fear. Some clever people will create an illusion of the outlet being grounded by running a wire from the ground attachment point to the neutral wire. The thinking to justify this is that grounds and neutrals attach in the panel box, so this should work, but it does not. Ground wires allow the current to be dissipated when there is a failure in the system, which cannot happen when the neutral is used as both a ground and neutral wire.
Securing conduit and outlets is another area of concern. Here is the scenario: you have a work bench in your garage, and you need an outlet for your power tools. The garage is already finished with sheetrock that you do not want to cut into, so you place the junction box on top of the wall along with the conduit. Is it secured properly? The conduit was not secured to the wall, and the box was not secured, so either could be easily knocked allowing live wires to become exposed. I have seen this done in a house, but garages have this installation more often.
Those are items you should look for in an older home. If you are not hiring an inspector, you have to pull the outlets to see if they installed a ground wire. The ground will be green or bare copper. In Europe they use brown wire, which you may find here in the states although it is not supposed to be done in that way.