Dear Jim: We have many electronic gadgets in our house and I am concerned about a voltage surge ruining them. Are there whole-house surge suppressors which will protect everything electric in our house?
-- Sandi S.
Dear Sandi: People often think of only electronic gadgets such as computers, game consoles and audio/visual items, as being at risk from electrical surges. Actually, nearly every electric item in a house today has some sort of sensitive electronics which can be damaged by a surge. These include ranges, dishwashers, air conditioners, fans, etc.
A very common source of an electrical surge is a thunderstorm. The voltage and current spikes from a lightning strike are enormous. If your house and wiring experience a direct or very nearby hit by lightning, even a good surge suppressor likely will not be able to protect all electronic items.
When a storm is forecast and you begin to hear the thunder off in the distance, unplug as many of your electronic devices as possible. Just switching them off may not be adequate protection. A huge voltage surge can arc across an open switch and still fry the electronic components.
It often is repeated, smaller electrical surges which damage electronic equipment over time. These can be generated from the switching on and off of inductive equipment (usually electric motors) in nearby businesses. Some of these smaller surges can even be generated by your own vacuum cleaner, refrigerator compressor or clothes washer motors in your house wiring.
These smaller surges can slowly break down wire insulation or some electronic components over time. Eventually a wire may short out or the electronic component begins to malfunction and the appliance fails.
There are several types of whole-house surge suppressors available. Some mount on the circuit breaker panel indoors or are built into a circuit breaker. Others are designed to mount underneath an electric meter. Many electric utility companies sell and install the electric-meter-style units for you. The circuit breaker panel models are not difficult to install, but hire an electrician to do it.
There are differences in the protection provided by various surge suppressors. A common design uses metal oxide varistors (MOV) to absorb the electricity surge and dissipate it before it flows through the house wiring.
A physically larger MOV can absorb a larger surge. The basic specifications to compare surge suppressors are the maximum surge current (amperes) and the total energy dissipation (joules) it can handle. A higher number for both is better.
Even though the surge suppressor protected your electronics, a large surge many burn out the MOV. Many models have a light on them to indicate if it is still function or not. Check it regularly and especially after a thunderstorm.
The following companies offer efficient surge suppressors: Eaton, (800) 386-1911, www.eaton.com; Emerson Network Power, (800) 288-6169, www.emersonnetworkpower.com; Intermatic, (800) 391-4555, www.intermatic.com; and Meter-Treater, (800) 638-3788, www.metertreater.com.