DIN Rail Mounted Doorbell Transformer

[turningtim]

given spare space in a CU a DIN rail mounted transformer makes a neater job I can sleeve the "bell" wire to bring its insulation up to spec but does it have to have its own MCB (6amp MCB seems a bit over the top!)or can short tails be joined to another MCB -ring main (as it is in essence just a spur) or lights?

 

[bernardgreen]

Wire it to one of the lighting circuit MCBs so you will be aware of loss of power to the door bell.

But based on recent experience fitting a transformer and associated 12 volt wiring inside a consumer unit is best avoided if there is space on the wall for the transformer. Even fitting a DIN rail transformer in a one or two module DIN rail housing is better than it inside the CU.

 

[turningtim]

thanks -if i wire it outside the CU (the ones i was looking at were DIN or wall mount) does it have to be fed via a fused spur or can I just run T&E outside the CU as I would have done if it was all in the CU -we're talking all of 6" here?

 

[bernardgreen]

I would use a fused spur or clock outlet to provide a fuse for the transformer.

This enables the bell to be turned off for peace or maintainance.

Most transformers have a built in "safety device" but not all will be 100% effective in some fault conditions and if the faulty transformer has to rupture the 6 amp fuse of the lighting ciruit before the supply is removed that tranformer can get very hot ( 6 amps equates to over a kilowatt of power ). That is why I prefer them outside the CU.