True DC

Many alternative solutions, particularly those based upon an AC Switch Disconnect design which use bridge contacts, have been modified and rated for DC operation.

In the move towards safer installations of PV systems,[3] whether it be in a domestic or industrial environment, consideration has to often be given to the materials and the risk of fire hazard[4][5] that they pose.

Ratings referred to under the UL 94 category are deemed generally acceptable for compliance with this requirement as this cover tests for flammability of polymeric materials used for parts in devices and appliances.

Although there are 12 flame classifications specified in UL 94, there are 6 which relate to materials commonly used in manufacturing enclosures, structural parts and insulators found in consumer electronic products.

This UL508I standard specifically covers switches rated up to 1500 V that are intended for use in an ambient temperatures of -20 °C to +60 °C, and that are suitable for use on the load side of PV branch protection devices.