Electric Power Problems: Surges

The electric power that heats/cools our homes, cooks/chills/freezes our groceries and runs our all-important computers, televisions and other electronic appliances is known as “120-volt, 60-Hz single-phase oscillating” current. That means that at any given time, the current can vary from 120 to 169 volts. The appliances we use are designed to cope with that much oscillation.

A power surge is a delivery of current at more than 169 volts in the form of a 1/1,000-second arc of electricity. It can be caused by power company grid-switching, on-off switching of large appliances like air conditioners, tripped circuit breakers and short circuits and—most often and most powerfully—lightning. It enters your home through telephone lines, service lines and TV cables and will harm your equipment and appliances; very often, they will not work after a surge. Repeated smaller surges can also erode or break down components.

To protect your most valuable equipment from power surges, acquire a point-of-use surge protection device (SPD). Most of them look just like a multi-plug strip (but don’t confuse the two—an ordinary strip offers no protection). You can also install special electric outlets that protect whatever is plugged into them. The SPD channels the extra voltage into a grounding wire that prevents it from flowing into your device. It should accommodate 600 joules or higher, especially if you plug in more than one appliance. Make sure any SPD you buy is listed as UL Standard 1449, which shows that it has been thoroughly tested. It is best to select one that indicates by a flashing light or audible alarm that it needs replacement.

The most complete protection combines SPDs with a service-entrance or electric-panel surge protector. This device protects your entire system, including items that are “hard-wired,” i.e., not plugged in. Your APHC professional can advise you on installing it.

A direct lightning strike will overwhelm even the best surge protection equipment. If a big storm is approaching your home, protect yourself by unplugging valuable equipment.

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