How do American power strips achieve surge protection?

American power strips achieve surge protection through the incorporation of surge protection components and technologies that divert excess electrical energy away from connected devices. Here's how surge protection works in American power strips:

1. Metal Oxide Varistors (MOVs): The primary surge protection component in most American power strips is the Metal Oxide Varistor (MOV). An MOV is a semiconductor device made from zinc oxide with a ceramic-like appearance. It is connected between the power line (hot) and the ground wire within the power strip.

2. Normal Operation: Under normal operating conditions, the MOV has a very high electrical resistance and allows the standard voltage to flow through it without impedance. In this state, the power strip functions like a regular extension cord, providing a pathway for electricity to reach connected devices.

3. Surge Event Detection: When a surge or voltage spike occurs in the electrical supply, such as due to a lightning strike, power grid fluctuations, or other disturbances, the voltage level rapidly increases beyond the normal operating range (usually above 120 volts in the U.S.).

4. MOV Activation: When the voltage exceeds a certain threshold, the MOV's resistance decreases dramatically, almost instantaneously, allowing it to conduct electricity. This happens because the MOV's semiconductor material becomes highly conductive in the presence of high voltage levels.

5. Diverting Excess Energy: Once the MOV conducts, it creates a low-resistance path to divert the excess electrical energy, including the voltage spike, away from the connected devices. This prevents the surge from reaching and damaging your equipment.

6. Voltage Clamping: The MOV's ability to divert excess energy is essential in limiting the voltage that reaches your devices. Surge protectors are typically rated for a specific voltage, known as the clamping voltage. When the surge protection activates, it clamps the voltage to a safe level, usually around 330-400 volts, depending on the surge protector's rating. This level is well below the typical 120-volt threshold of most devices, protecting them from damage.

7. Multiple MOVs and Stages: Some advanced surge protectors have multiple MOVs and multiple stages of protection. Each stage may have a different clamping voltage to provide comprehensive protection against various surge magnitudes.

8. Indicator Lights: Many surge protectors feature indicator lights that show if the surge protection is still active. If a surge causes the MOV to divert excess energy, it can degrade over time. Surge protectors with indicator lights help users know when it's time to replace the unit for continued protection.