You can connect the bell transformer to the mains in one of four ways. The simplest is to fit a length of flex to its input terminals, add a plug to the other end and plug this into a socket outlet. This is suitable only as a temporary solution.
The second option is to take a spur from a lighting circuit in the ceiling above where you want to fit the sounder, using 1mm2 two-core-and-earth cable (6). You can connect into the loop-in terminals of a modern ceiling rose, or cut the circuit cable and wire in a junction-box to which the spur cable is then connected. Turn the power off at the mains first. Connect the transformer's output terminals to the bell push and sounder with bell wire.
If you have to lift floorboards to make the connections, you can hide the transformer in the ceiling void and drop the bell wire link down to the sounder.
The third choice is to take the spur off a power circuit if this is more convenient than wiring into a lighting circuit. Again turn the power off first. Then connect a length of 2.5mm2 cable into the back of a suitable socket outlet, and run the cable to the feed terminals of a fused connection unit (FCU). Switch to 1mm2 cable for the link between the FCU's load terminals and the transformer's input terminals. Link the transformer's output terminals to the sounder with bell wire.
The final choice is to use a spare fuseway, in a modern consumer unit (8). Even when you have switched off the consumer unit to make the connections, the cable that connects the meter to the main switch is still live - so take care. Use 1mm2 cable to run the mains supply to the transformer.
Connect the live and neutral cable cores to the transformer's 240 volt terminals, but cut back the earth core at the transformer end of the cable since it is double-insulated and does not need earthing.
If you are specifying a new consumer unit, it can contain an integral bell transformer. In this case, the outgoing low-voltage bell wire from the transformer must be sleeved within the consumer unit, and it must not run to the bell in the same conduit as any mains-voltage cables.
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