What Are the Recommended Joules for an Outlet Adapter?

Significance

• As the components that drive electronic devices get smaller, they become more vulnerable to variations in the electrical energy that powers them. Portable equipment such as cell phones, laptops and personal music players depend on rechargeable batteries. Some outlet-bound devices have their own power supplies or internal protective circuitry to help control the voltage and quality of energy they receive. The rest are dependent on whatever is delivered by the power grid.

Dirty Power

• As if the voltage spikes, dips and general electrical "noise" on municipal power lines weren't enough, the worst enemy of sensitive electronic equipment is often your own appliances. If an air conditioner or clothes dryer can disturb the flow of electricity enough to cause your lights to dim, imagine what kind of havoc those on-off cycles can cause inside a high-definition television.

First Line of Defense

• A good surge suppressor cleans up the incoming power by filtering out potentially damaging spikes using electronic circuitry. Many of these circuits employ sacrificial components such as metal oxide varistors that block and then dissipate the surge. The unit of electrical energy used to rate the spike-handling capacity of this circuitry is called a joule.

Recommended Ratings

• As a general guideline, consider 1000 joules to be the minimum value for a surge suppressing outlet adapter. Ratings over 1900 joules are recommended for more sensitive equipment. Since the surge-handling capability of these adapters diminishes over time, a good suppressor should include some sort of tell-tale light or other means of knowing when it can no longer do its job. Other ratings to look for are a clamping voltage of 330 volts and a clamping response time measured in nanoseconds.