We must first start with a brief overview of how an electrical outlet should be wired. In most cases, residential wiring will have a "hot" wire, a "neutral" wire and a "ground" wire. In older homes, the ground wire may not be present. In order for an outlet to function correctly, it is important that each of these wires is connected to the correct part of the outlet. That said, the neutral wire (white) should be connected to the silver or grey screws which is usually found on the left side of the outlet. The hot wire (black or red) should always be connected to the brass screws on the outlet and the ground wire (green) should be connected to the grounding screw which is often a green color as well. If you were to look at a standard plug, the larger prong is the neutral side, the smaller prong is the hot side and the bottom rounded prong is the ground. Now that you know how to correctly wire an outlet, let's look at some common issues when things are not correct.
"Reversed Polarity"
Reversed polarity often occurs when the hot and neutral wires are switched at the outlet. In some cases, reversed polarity can occur upstream of the outlet which may be more challenging to resolve. The issue with an outlet having reversed polarity is that there is increased potential for an electrical shock. This occurs because the device that is plugged into that outlet could have components that remain energized even though it may be turned off by a switch. This happens because the neutral wire remains "hot" which is incorrect. Here is an example: A light bulb socket happens to have exposed electrical components of which the threads being the most exposed part. If the light socket is wired correctly, then the threads are attached to the neutral wire to prevent someone from getting a shock when changing a light bulb. If the outlet has reversed polarity, then those threads become hot or energized and therefore you have the potential to get shocked when changing that same light bulb.
In most cases the fix is simple and quick however any electrical work should be done by a licensed electrician.
"Open Ground"
"Grounding" is needed to provide a path for stray electrical current to follow is an important safety feature. Modern wiring codes require all outlets and fixtures to be grounded, meaning a separate wire and connection must be provided for current to follow in the event the wiring is compromised. An open ground means the safety path is open, disrupted or incomplete. This could mean that the ground wire was never attached, has become detached or has a poor attachment to the grounding screw. It could also mean that an outlet up stream has a grounding issue as well. Keep in mind that in older homes, grounding may not be present at all due to the fact that older wiring and outlets did not have grounding features. This issue should be evaluated and repaired by a licensed electrician.
"Double Tapped Breakers"
This issue is probably one of the most common finds during a home inspection. A double tapped breaker is when two wires connect to one single breaker. Most breakers, are only rated to accept a single wire. There are some exceptions to this rule however they are not seen often. The problem with "double tapping" a breaker is that it can cause loose connections in the electrical panel, fire hazards from arcing, and possibly premature tripping of a circuit. The common repair to this issue is what electricians call a "pig tale
". This is done by splicing the two wires together and then having a single wire from the splice attach to the breaker.
Hopefully this bit of information helps shed some light on some of the common electrical issues found during home inspections. Likewise, hopefully you have a better understanding of the associated issues with these findings. Any electrical issues should be evaluated and repaired by a licensed electrician. Attempting electrical repairs without the proper knowledge could lead to injury.
Image #1 shows an electrical outlet tester reading "reversed polarity" in an outlet
Image #2 shows a double tapped breaker - seen where the black and red wire is connected into a single breaker
Image #3 shows the "pig tale" repair of a double tapped breaker
Image #4 shows the correct wiring of an outlet
