The Absolute Basics of Electricity

If your home inspector ever told you that one of your receptacles had reverse polarity or an open ground, there is a good chance you had no idea what he was talking about. Because it’s more difficult to visualize electricity; it can be harder to grasp the basic concepts. With plumbing for example, you can see the water supply lines going to your sink and see the drain running away on a slope; it’s easier to see how A gets to B. Electricity can be just as simple; let’s use this crude hand-drawn diagram to break it down to its simplest terms and take a look at the common defects a receptacle can have.

Electricity is the laziest force in nature; it hates doing more work than it has to and always takes the easiest path to its destination. This is great news; it means we can always know where it will go. If we don’t want electricity to damage appliances, create fires, or shock people, we simply need to ensure the easiest path it can take is a safe one. In homes, we accomplish this by having the power come into the main breaker box from the utility company; travel to outlets, switches, and appliances via the HOT wire connections; and returning to the box (and utility company) via NEUTRAL connections. This system of loops (or circuits) tells the electricity where to go as it powers our stuff on its way by. This is true inside the appliances that are plugged into receptacles as well; power comes from the hot side (the little slot) of a receptacle, travels through the appliance and powers the motor or lights or whatever functions in the appliance, and leaves via the neutral side (the larger slot). The breaker box allows for a large number of these circuits, but the system as a whole is one giant loop. The GROUND wire (the round slot in receptacles) is simply a backup in case the neutral fails (a wire comes loose from its connection, a mouse chews through it, etc.). If the neutral does fail, we wouldn’t want you to be the next best path! This means that in a perfect scenario, the ground wire is never used. We can use switches to prevent the HOT wire from continuing through the rest of the circuit so we only have power when we want it. This is most commonly used to turn lights on and off. On the light switch on the diagram, if it was in the off position, no power would get past the switch, and would simply “turn back” via the neutral at the switch. If it was on, the power would have to go around the long way through the light to get back to where it wants to go (via the neutral path). By giving electricity only one path at a time, we can know exactly where it will go.

To work properly, receptacles are designed to have the three different wires connect in specific places. When they are not connected properly, it can create a safety hazard; these incorrect connections are the defects that your inspector is looking for. OPEN GROUND means the ground connection on the receptacle is not wired correctly and no backup exists if the neutral were to fail. With a two-prong outlet, there is no ground connection point, and is referred to simply as UNGROUNDED (which is not necessarily considered a defect depending on the location). OPEN NEUTRAL means the neutral connection is not present. The receptacle will still work because the electricity is using the ground to get to where it’s going, but is unsafe as it doesn’t provide a backup in case of failure. Another possible scenario is when the hot and ground, or hot and neutral connections are reversed; commonly known as REVERSE POLARITY. The reason this is a concern is that any appliance plugged into an outlet like this will be electrically charged at all times, but only functional when a switch is activated. This means that the metal sheathing around a light socket or the metal wires in a toaster would be a shock hazard; even when it appears to be off. While the breaker box is designed to mitigate the danger of these defects, they can still result in damaged equipment or electric shock and should be corrected.

If you’ve reached the end of this article, you may have more knowledge of electrical systems than your friends and family; congratulations! Now get yourself a tester, go into their houses and find those defects (just kidding)!