With the advent of Low Cost 12V Halogen Lighting is is now extremely simple to provide emergency lighting for use during power cuts. All that is required is a relay between the lighting transformer and one of the low voltage lights. With the relay in its released position the lamp is connected directly to the transformer secondary as normal. When the relay is operated, the lamp is connected to a 12 volt supply from a car battery.
Adding emergency lighting to existing chandeliers and other light fixtures can easily be achieved by using a 12V capsule lamp and a low cost wire ended holder. The 12V lamp is so small that it is easy to fix within the same enclosure as the main lamp. Make sure that the low voltage lamp is not in contact with anything flammable as they get very hot in use.
A fluorescent fitting can be given the emergency treatment by stripping the innards from a caravan style fluorescent light and mounting the electronics within the existing fitting. The tube can be attached to the existing tube by means of cable ties. Once the diffuser is refitted the modification becomes invisible....until the power fails!
The circuit for modifying existing fittings is even simpler.
Use 2.5 Twin & Earth cable to connect the fixture back to the car batteries. This may seem like a very heavy gauge cable for a lamp which will draw less than 2 amps but the cable may be quite long and the halogen lamps dim noticeably with even the slightest volt drop. For the same reason use one cable per room with a maximum of 2 lamps (40W). Use the Red wire for +12 volts, the Black wire for 0 volts (-ve) and the bare earth conductor suitably sleeved at the ends for the control wire.
Most 2.5 Twin & Earth cable found in houses will have a GREY sheath. It is possible to buy 2.5 Twin & Earth cable with a WHITE sheath. This is usually found in DIY centres but can also be obtained from electrical wholesalers. I would recommend that you purchase cable with a different sheath colour for your LOW VOLTAGE WIRING to make it easily distinguishable from the MAIN VOLTAGE WIRING.
WARNING. A CAR BATTERY IS CAPABLE OF VERY HIGH CURRENTS WHICH CAN CAUSE EXPLOSIONS, BURNS & FIRE. PLEASE PAY PARTICULAR ATTENTION TO THE FUSING ARRANGEMENTS. IF YOU HAVE ANY DOUBTS, DO NOT ATTEMPT TO INSTALL THIS SYSTEM.
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