8533.40.40.00 - Metal oxide varistors

This HTS category, 8533.40.40.00, specifically covers Metal Oxide Varistors (MOVs). MOVs are voltage-dependent resistors, meaning their electrical resistance varies with the applied voltage. They are primarily designed to protect electrical and electronic equipment from transient voltage surges and spikes, such as those caused by lightning strikes or power system switching. Their function is to clamp excess voltage by significantly decreasing their resistance when the voltage exceeds a certain threshold, thereby diverting the surge current away from the protected equipment.

This classification is distinguished from its sibling category, 8533.40.80, which encompasses "Other" variable resistors. While both fall under the broader heading of "Other variable resistors," the specific inclusion of Metal Oxide Varistors in 8533.40.40.00 isolates them for distinct statistical and tariff treatment. The key distinguishing factor is the unique material composition (typically a ceramic matrix of metal oxides like zinc oxide) and the specific surge-protective application characteristic of MOVs, as opposed to other variable resistors whose primary function might be signal adjustment or control.

As this is a leaf node within the HTS structure, there are no further subcategories. Therefore, classification at this level relies on accurately identifying the product as a Metal Oxide Varistor based on its construction, materials, and intended function of surge suppression. Examples of products falling under this code include individual MOV components used in power strips, power supplies, and industrial electrical systems for overvoltage protection.