I am not in with transient overvoltage field. However it seems the new UL 1449 third edition
presents 4 destination types:
?Creation of Four Type Designations:
Previous editions of UL 1449 classified surge protective devices into two types: permanently connected or cord-connected. The 3rd edition scraps that system and sorts SPDs into four types, depending on where they are located within an electrical distribution system:
Type 1 - Permanently connected SPDs 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 intended to be installed without an external overcurrent protective device.
Type 2 - Permanently connected SPDs intended for installation on the load side of the service equipment overcurrent device; including SPDs located at the branch panel.
Type 3 - Point of utilization SPDs, installed at a minimum conductor length of 10 meters (30 feet) from the electrical service panel to the point of utilization, for example cord connected, direct plug-in, receptacle type and SPDs installed at the utilization equipment being protected. The distance (10 meters) is exclusive of conductors provided with or used to attach SPDs.
Type 4 - Component SPDs, including discrete components as well as component assemblies.?
It seems to me that type 2 would be still located on the supply side of the line-overcurrent device is here located. Does not it? :weeping: