Type 1 and Type 2 Surge Protective Devices, Differences between?

Type 1 devices are installed before the main device in the loadcenter, whereas Type 2 are installed following the main devices in the loadcenters. As stated in the catalog: "Type 1 Surge Protective Device (SPD)s are intended for installation between the secondary of the service transformer and the line side of the service equipment overcurrent device, as well as the load side, including watt-hour meter socket enclosures, and are intended to be installed without an external overcurrent protective device. Type 1 devices are dual-rated for Type 2 applications as well, providing the highest ratings available for installation at the service entrance.

Type 2 Surge Protective Device—Permanently connected Type 2 SPDs are intended for installation on the load side of the service equipment overcurrent device, including SPDs located at the branch panel." For more information, please the catalog section or the Surge website.