Surgelogicâ„¢ Type SDSA is used mostly in service entrance panels to provide an efficient and economical means of surge suppression. The surge suppressors use two pole spaces in a QOâ„¢ or Homelineâ„¢ load center, or NQ panelboard. SPD are three phase and are rated for use in an indoor or outdoor enclosure. Ideal for residential and light commercial use, these SPDs provide a dependable first layer of surge protection. It is designed to protect electrical service and major household appliances, excluding electronic devices. Designed for 3 wire 600VAC delta three phase systems. Securing up to 50kA surge current per phase. This surge protection device is UL Listed.