All Leviton SPDs incorporate large MOVs as opposed to lower cost small MOVs in parallel. Large MOVs offer an improved surge current rating and greater reliability, which ensures that the product will perform for many years. Surge products are classified in catagories (A,B and C) as defined in the IEEE Trilogy of standards. Catagory C ranges from the transformer secondary to just inside the building entrance. Catagory B includes all of the branch or sub-panels and Catagory A includes the receptacles and point-of- use devices such as cord-connected or plug-in surge devices. Surge products are also Typed to harmonize with the IEC 61643-1: Surge Arrestors/Type 1 are typically mounted on the line side of the main service entrance. They protect against external surges caused by lightning or utility capacitor bank switching. They use the largest MOV’s in the business (40mm & 53mm) and are outdoor rated. Plus, some of our Type 1 SPDs feature an audible alarm warning that the device is no longer providing the rated surge protection. Surge Panels/Type2 typically serve a branch circuit and protects against residual lightning energy, motor driven surges and other internally generated surges. Leviton Type 2 surge panels use UL-recognized surge fuses. They offer models that contain replaceable modules, surge counters and 7-Mode protection. They also offer models that can be used for both Delta and WYE transformers. These SPDs conform to NEMA LS 1 guidelines. |