Here are just a few you may of heard of: BriefingWire.com, 5/17/2021 - SPD - Surge Protection Device (The product designed to protect electrical devices from voltage spikes) TVSS - Transient Voltage Surge Suppressor (Replaced by the acronym SPD) MCB - Miniature Circuit Breaker RCBO - Residual Current Circuit Breaker with Overload LPS - Lightning Protection System (eg: lightning rod / conductor, earthing wire system, ground rod) MOV - Metal Oxide Varistor (Technology used within some SPDâs) SAD - Silicone Avalanche Diode (Technology used within some SPDâs) GDT - Gas Discharge Tube (Technology used within some SPDâs)