I’m often surprised by the number of homes I inspect that do not have correct wiring throughout. Older homes typically have ungrounded, two-prong receptacles (outlets) because grounded receptacles didn’t used to exist. But even many newer homes have grounded (three-prong) receptacles that are either not actually grounded or are improperly wired.
Let’s begin with a simple lesson on electricity. The easiest way to understand electricity is to think of water. Like water, electricity “flows” in a “current” along a path. Like water, electricity has a certain pressure it flows at and a certain level of “resistance”. The primary difference between the two is that while water enters a fixture from a supply source in one location and ends up in a different location after it is drained, electricity always seeks to get back home to its original source and travels along a continuous circular path. A “circuit” is merely a completed circular path of electricity.
For a typical home, electrical power begins at a plant where electricity is generated. The electricity travels in high voltage through cables and is reduced by something called a transformer, which “transforms” the electricity into a smaller amount that is more suitable for supplying homes – typically 100 amps / 120 volts or 200 amps / 240 volts. Without the transformer reducing the voltage, the amount of electrical power would be too great and our appliances and other devices would be overloaded and fried. The electricity then enters the house’s electrical panel through service entrance lines (usually aluminum) and travels through branch circuit wiring (usually copper) to the various switches and receptacles that power the items we use that require electrical power. The electricity flows to devices on a “hot” wire (usually black) and then back to the panel on neutral wires (usually white), and finally back to the street and the power plant. If a third wire is present, it is bare copper and is the ground wire. If you look at the three slots on a grounded outlet, the shorter slot is the hot side, the longer slot is the neutral, and the small circular hole is the ground.
So what exactly is grounding? Well, like water, electricity always seeks the path of least resistance. Under normal conditions, electricity freely flows through hot lines and back through neutral lines, but occasionally things happen to interrupt that natural flow. Water may enter a receptacle, an object that conducts electricity may be inserted by a child, or a circuit may be overloaded by drawing too much power and the circuit breaker at the panel may fail to trip. In such cases, these things cause a “roadblock” to the current’s normal path, and the electricity is forced to take a “detour” along a different, unintended path. If that happens, we need the electricity to stop as quickly as possible, and the best way to do that is by grounding. As its name suggests, grounding is literally providing a path along a conductor for the electricity to travel to the ground, which does not conduct electricity, so the unsafe current is stopped dead in its tracks. Without proper grounding, people can easily become the source of grounding for the current and be shocked since our bodies are unfortunately good conductors of electricity.
Aside from improper grounding, reverse polarity is another fairly common wiring defect. In this case, the hot and neutral wires are reversed. While this does not always pose an immediate threat and may go unnoticed, there are some circumstances where reverse polarity can pose a safety hazard. For example, if a light socket is wired in reverse, the metal socket becomes energized and touching it will cause shock. Correcting this problem by switching the wires to their correct screws is simple, but all electrical work should always be done by a qualified electrician and the main breaker at the panel should always be shut off to ensure that no accidents occur.
Last but not least, most homes have at least one receptacle that is missing a cover, usually in a less visible area like the back of a kitchen base cabinet or behind the night stand in a bedroom. This may not seem like a big deal, but covers shield the wiring and provide protection that is necessary – especially for young children. Installing cover plates is probably the cheapest and easiest job a homeowner can do, and there’s really no excuse for having receptacles or switches that are uncovered.
Hopefully this post has clarified some things for you about how electricity works and how to spot and correct wiring defects. One nice thing about electricity is that if there’s a problem it usually lets you know right away. Check your receptacles with a tester to ensure that your home is properly wired and safe. Testers are inexpensive and most are accurate and reliable. If you come across any defects, contact a qualified electrician for immediate repair.
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