Phoenix Contact 2800994 A surge protection device features a protective plug and base element, often integrated into a module with a multi-stage status indicator for three signal wires sharing a common reference potential. It achieves indirect grounding using a gas discharge tube, suitable for high-frequency applications and telecommunications interfaces that don't require an external power supply, such as those with speeds up to 90 Mbps. This type of surge protection can also be used in safety-related circuits rated at SIL 3 or higher.