Installing a Doorbell


Make sure your callers can make themselves heard by installing a bell or chime for them to ring. You can choose a battery or mains-powered model.

A doorbell or chime is a more reliable way for callers to announce their presence than a knocker, because you can place the sounder where you are most likely to hear it.

You need minimal DIY skills to install a battery-powered bell - just the ability to drill a few holes and drive in some screws. Fitting a mains-powered bell requires basic electrical skills to ensure that the mains connections are made correctly and safely.

Care needs to be taken when connecting up a bell transformer permanently to the mains supply. There are no safety risks involved in fitting a battery-powered bell.

Choosing Your Doorbell

The cheapest sounders are buzzers and bells. Traditional tubular chimes are more expensive. You can also choose chimes with a microchip inside that can play a variety of tunes.

Battery-operated systems are the cheapest to buy and the simplest to install. The batteries may last for a couple of years, depending on how often the bell is rung.

Mains-operated systems cost more to buy because you need a small transformer to power them, but once they are installed they then have minimal running costs. They are often more compact than battery-operated types because they do not need a battery compartment. They also allow you the luxury of having an illuminated bell push.

Planning the System

Start by selecting the best position for the bell push. It should be visible and sheltered from rain and excess heat, so is usually sited either on the door frame or close to it. Mounting on the frame is the simpler option because you can screw the bell push baseplate directly to the woodwork and also drill a hole through it with just a twist drill to take the wire to the sounder.

Next, decide where to place the sounder unit. It is normally put in the hall, but it can be placed in a living room or kitchen if you are more likely to hear it there. However, you should avoid an over-long circuit if you are installing a battery-operated bell.

If you also need a doorbell at the back door, you can fit two separate bell pushes and sounders. Alternatively, choose a sounder offering two different tones, so you can tell which bell push has been used.

Work out the best route for the cable between the bell push and sounder. Since bell wire is slim and unobtrusive, most people simply surface-mount it, running it in the angles round door frames and along the edge of skirting boards, picture rails or ceiling coving.

For mains-powered systems, make sure you purchase a transformer with an output voltage that matches the needs of the sounder unit - often 3 or 5 volts for bells and buzzers, and 8 volts for most chimes. Some transformers have three output terminals; select the pair that gives you the output voltage you want.

Find the best place for the transformer. Bell transformers are relatively small and unobtrusive, and can easily be concealed in a hall cupboard, or even in the void beneath a timber floor if the power supply is being taken from an existing light or power circuit.

Decide how to provide the power supply to the transformer. The simplest way is to plug it into a socket outlet, but there may not be one available, and the flex between socket and transformer is difficult to conceal neatly.

You can run a spur directly off a lighting circuit by connecting 1mm cable into a loop-in ceiling rose or into a junction-box connected to the lighting circuit. If it is more convenient to use a power circuit, you can run a spur in 2.5mm cable from a suitable socket outlet to a fused connection unit (FCU) fitted with a 3-amp fuse, then run 1mm2 cable from the FCU to the transformer.

If you have a spare fuseway in a modern consumer unit, you can fit a 5 or 6-amp miniature circuit breaker and use this to supply a circuit to the transformer. If you are specifying a new consumer unit, you can include a bell transformer within it.

Installing a Battery-Powered Bell Kit

Install the bell push first. At its chosen position, drill a 6mm diameter hole through the door frame or the wall. Pass a length of bell wire through it from indoors.

Drill a bigger hole if the bell push is a flush-fitting type with a barrel-type switch projecting from the back. Drill the larger hole first.

Separate the cores for about 25mm and strip 10mm of the insulation from each one. Remove the cover of the bell push and connect one core to each terminal on its baseplate. Then draw the wire back through the hole until the baseplate fits flush with the frame or wall surface, make pilot holes for the screws with a bradawl and screw it in place.

Fix the sounder baseplate at its chosen position. Then run the bell wire from the bell push towards it, clipping the wire every 150mm or so to ensure that it lies flat. When you reach the sounder, insert the wire through the entry hole. Separate the cores and strip the insulation as before, then connect the cores to the sounder terminals. Fit the batteries (most use four 1.5 volt cells), test that the unit works and fit the sounder cover.

Installing a Mains-Powered Bell

Install the bell push (which may be the illuminated type) as for a battery-powered bell, and run the bell wire back to the sounder position. Leave a loop there and run the wire on to where the transformer is situated.

At the sounder position, separate the looped cores, cut them and connect them to the terminals specified in the manufacturer's instructions. Then fix the baseplate to the wall and fit its cover. Connect the other end of the bell wire to the transformer's output terminals, and connect the transformer to the mains.

Providing Power for the Transformer

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 1mm two-core-and-earth cable. 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 2.5mm 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 1mm 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. 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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