While carrying out routine maintenance on a Victor Emergency Light fitting, an Electrical Technician received a minor electric shock. He was re-attaching the removable envelope of the light fitting at the time, and in the process of re-attachment, his hand touched the casing of one of the Battery Indication LED’s. It was from this casing that he received the shock. The Technician then applied his Seaward line tester to the LED casing and checked it for potential. He found that the tester indicated the LED casing was live at 254V AC with respect to earth. At this point he adopted correct procedure and applied isolation to the circuit concerned.
Victor fittings are designed so the envelope may be removed while the whole circuit is energised; the fittings being equipped with micro-switches to disconnect the individual fitting supply as the envelope is removed. It is normal practice to “re-lamp” whilst the whole circuit remains energised.The LED’s are an Ex rated item and are constructed from a plated machined housing containing a lens (red or green), into which an LED indicator is “potted” with a resin-type compound. The LED and its associated lead-out wires are fully insulated from the metal casing. The LED’s are mounted in the moulded plastic lid of the Ballast housing. This is removable and provides access to the internal connection terminals, ballast and associated control gear for the light fitting.
An examination within the Ballast Housing determined that the LED casing in question had been in hard contact with one of the supply cable cores. Due to the “Soft” nature of the Cable insulation, the resultant constant pressure had, over a period of time, caused the LED casing to penetrate and come into contact with the cable core. (See attached Photograph). In this instance it was the live core which was penetrated.Because the LED’s are mounted in the Moulded Plastic lid and are not earth bonded, The RCD protection on the lighting circuit was rendered ineffective. Had the two LED casings been mounted through a metal bonding strip or earth rings, and suitably connected to the Circuit Protective Conductor (Earth core) the RCD protection would have operated and rendered the circuit safe (isolated). A normal process of fault-finding would then have been instigated.
1. Add an earth bonding check on the LED casings and fit earth bonds.
2. We will communicate the design issue to the manufacturer.
LED casing on Victor Emergency Light Fitting