Retention Socket, SIS

A passively safe street lighting column located at the island of a bypass was knocked down in a vehicular collision.  

However, at the moment of impact the crash site was instantly safe from all voltages as the column was connected to the SIS electrical disconnection system.

In this instance a SIS Mini system was fitted in a mini pillar in close proximity to the column and fed from the existing power circuit. The system consists of a SIS Solo monitor board within an IP67 enclosure and has been designed to easily allow a retrofit passive column installation.

The passive column is fitted with an impact sensor which is accessed at ground level via the column door. When an impact to the column occurs the sensor communicates with the SIS monitor board, triggering a complete isolation within 0.2 seconds of impact.

The red “fault trip” LED on the monitor board will flash to indicate an impact has occurred and that power is no longer being supplied to the column.

Disconnection is guaranteed even if the structure has not detached from its base, which in turn safeguards the vehicle occupants and emergency service personnel at the scene of a road traffic incident. Once the new column was fitted in the existing NAL Retention Socket, the SIS system is reset and power to the column is restored.