The importance of a thorough electrical inspection is often under rated. Greg and Richard explanwhat can be discovered during an inspection.
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We call them electrical receptacles. Some people call them electrical outlets and, yes, we do check them. Not every single one because receptacles are often behind furniture or stored items that are not readily movable; but we spot-check at least one in each room.
Two circuit analysis tools, one low-tech and one high-tech, are used: a simple 3-light tester that checks wiring configuration, and also a more sophisticated circuit analyzer that checks voltage, voltage drop under load, resistance to ground, plus tests GFCI and AFCI receptacles.
Before we go into what defects the electrical receptacles are tested for, let’s review the basics of receptacle wiring. A modern receptacle that accepts a 3-prong plug has a specific designation for each opening: the shorter of the two narrow slots connects to the “hot” wire (the one that can shock you), and the taller slot is the “neutral” (which completes the circuit), and the round hole is the “ground” (an alternate safety route for electricity that has gone astray, not found in pre-1960 2-slot receptacles). Each of the three wires in a typical 120-volt electrical cable must be connected securely to the right receptacle terminal for it to function correctly.
Here’s some typical defects we find:
If the wires going to the hot and neutral terminals are switched, you have reverse polarity. While this defect does not affect the operation of simple appliances like a lamp, it can make them more dangerous. In the correct wiring configuration, the hot wire is connected to the button at the bottom of the light socket and the neutral is connected to the socket threads. When replacing a bulb in lamp that is connected to a receptacle that is wired properly, it is difficult to be shocked by the small button at the bottom of the socket. But a reverse polarity receptacle electrifies the threaded socket, making it more likely that you will be shocked when changing a light bulb.
Older 2-Slot Receptacle
Two-slot receptacles, the ungrounded type that were typical in homes before 1960, are considered safe and we do not list them as needing repair. However they are noted, because 2-slot receptacles will not accept the 3-prong plug on the cord of many new appliances, that require a ground connection to work properly, and this may prove to be an inconvenience.
Homeowners in older homes sometimes succumb to an easy, but unsafe, solution to plugging the 3-prong cord on their new refrigerator to the 2-slot receptacle behind it. They use a conversion gadget we call a “cheater plug.” It has 2 prongs on the back side and three-slots on the front, along with a short wire for connection to the screw at the front of the receptacle box cover--although the receptacle box is rarely actually grounded. We always call out cheater plugs for repair.
Another shortcut for upgrading older homes to accept 3-prong plugs is replacement of 2-slot receptacles with 3-slot receptacles, even though there is no ground connection available. This is a typical defect in older homes that have had a quick, cheap remodeling to be “flipped,” and it is a serious safety defect.
Yet another shortcut to installing 3-slot receptacles in an older home is a “false ground,” where the ground slot is connected to the neutral terminal of the receptacle. Again, no ground connection exists and we call it out for repair.
When our circuit tester indicates no neutral connection, it usually a loose wire in the receptacle box or the main panel.
High Resistance to Ground
In order for the ground to work properly as a safety device, it must have a low resistance to the flow of electric current so that a breaker is tripped quickly when electricity starts flowing to the ground. Electrical resistance is measured in ohms, and 1.0 ohms is the recommended maximum resistance.
The nominal voltage for household receptacles is 120 volts, but between 110 and 130 volts is acceptable. We note if the voltage at receptacle is outside this range.
Excessive Voltage Drop Under Load
Voltage is a measure of electrical force, which is comparable to water pressure in a plumbing system. When a standard 15-amp load (approximating a large household appliance or several smaller ones) is applied to a 120-volt household circuit, the voltage drops somewhat. The maximum acceptable voltage drop is 5%. More than that indicates poor wire connections, damaged, or undersize wires.
We “pop” and reset GFCI receptacles and breakers to test them. Like any mechanical device, they begin to fail as they age.
We “pop” and reset AFCI-breakers to test them. They also begin to fail with age and, occasionally, we find defective new ones.
Any receptacle that is not supplying current is marked for repair.