Are Type 1 surge protective devices allowed to be installed on the supply side of the service disconnect overcurrent protective device?

Type 1 surge protective devices (SPDs) are designed to be installed on the load side of the service disconnect. This placement ensures that they protect the electrical system and connected equipment from surges that could occur after the service disconnect, ensuring effective operation within typical residential or commercial applications. Installing them on the supply side would mean they are positioned before the overcurrent protective device, which is not compliant with standard electrical codes and practices.

This requirement is based on the need for proper coordination with overcurrent devices and safety standards, which are set to prevent damage to both the surge protection devices and the equipment they are meant to protect. Positioning an SPD correctly helps maintain functionality and safety, making it essential to adhere strictly to the guidelines surrounding their installation.