Wired Doorbells can be powered by batteries only, transformer only or either battery or transformer depending on the model. Transformers connect to the mains and drop the voltage from 240v to 8v a/c for safe operation. They all must be connected to a wired bell push button which can be illuminated for transformer operation, but cannot be illuminated for battery operation. A selection of bell push buttons is shown [ Click Here ]. All wired units can be extended with wireless units if a Wired to Wirefree Extender is connected into the wiring from the bell push button. All transformer powered models must operate between 8v - 12v ac and be supplied with 1 amp (transformer 7770). If 2 bells are operated on the same system then the total current supplied will need to be 2 amps (transformer 7781). It is important that bell wire or equivalent is used that can handle 1 amp (do not use Cat 5 or telephone cable) - we supply 9m lengths code 7200 on our website.
The model which is only powered by batteries is the, 1219W , whereas Wired Models that are only mains powered are the 1200B, 1210BK , 7721CR, 230W, 231S, L321H, L321M, L321N, L321T, (via a transformer) and the 776W (which includes a transformer). Models 230W & 231S have their own internal transformer, but can also be powered by an external transformer.