When buying a home, you might have a home inspector prepare a report of the issues that need to be addressed in the home. It is very important to review those reports carefully and have a licensed master electrician review the suggested electrical repairs before you purchase the home. Two common items seen on home inspection reports are reverse polarity (in receptacle outlets) and double taps (in the electrical panel). We want to explain what those mean and how they can be addressed.
Reverse polarity basically means the receptacle outlet has been wired backwards. This issue can be discovered with the use of a simple tester. If the outlet wiring is reversed, the tester will show with its light display that the hot and neutral wires are reversed, as you can see in this picture.
The most common cause of this issue is that a professional electrician did not install the outlet. Many homeowners replace their own switches and outlets in their home but don't realize that they can easily mix up the wiring and cause issues later. Outlets that have been wired incorrectly can be very dangerous.
One of the most dangerous mistakes made when homeowners install their own outlets is that the connections are not tight. This can easily lead to a house fire. The wires should be installed clockwise around the screw terminals (see picture below). It is common to get one side of the receptacle correct but when you turn it over to make the connections on the other side, it is 180° backwards. If you do it backwards, you think you are tightening the screws but it is actually spitting the wire off and loosening the connection. Recently this happened to a customer of mine. They have a two-year old and a new baby. There was only one outlet being replaced so they thought, "no problem, this seems too small to call an electrician out to replace just one." The plug and the side of the box were burned up really badly due to the wires on one side being installed backwards under the screw terminal as I described above. I made the repair, but that was a close one!
Even more importantly, if the power is not off when you start changing wires and you get shocked it can go through your heart. How this happens is that if you slip when you are holding the outlet in one hand and the wiring in the other, the hand holding the outlet is grounded. When you slip off onto the hot wire, the power goes from one hand to the other through your heart.
This is a simple repair. I will make a splice connection to bring both wires into a single connection and meet code for one wire per connection at the breaker. The bottom breaker in the picture below has been repaired this way.
Are you considering a residential remodel project, an electrical panel change or upgrade, or a garage or shop electrical project? Thomas Adams is an Oregon Master Electrician, with an Inspector Certification, who has over 25 years of experience in the industry and he would be happy to talk to you about your Tualatin electrician needs.