Replacement door bell/chime transformer

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Would appreciate a heads-up on replacing a blown door bell/chime transformer.

The transformer, a very old Friedland "Surepunch" model sited in the loft space, went open circuit (though not before blowing a fuse in my old distribution box) and smells burnt. Because of the worrying burning smell, I removed transformer from it's 5 amp lighting circuit and replaced with a suitably rated mains junction box. Also booked in local electrician to sort out door bell transformer issue and replace old distribution box with new one, but that's a couple of weeks away.

Meanwhile, I'd like to educate myself a bit more about door bell/chime transformers so I better understand my options. I appreciate the entire old bell/chime setup could be replaced with a modern equivalent but I kind of like the idea of keeping the old setup going - albeit with a new power supply. I've contacted Honeywell Friedland and asked them to suggest a suitable replacement transformer. Heard nothing from them as yet so I started to Google and saw both stand-alone and DIN rail mounted transformers. Seeing as I'm having the old distribution box replaced, is a DIN rail mounted transformer designed to fit into a modern distribution box? Or should I opt for an equivalent transformer swap, assuming a suitable model is available (the bell/chime was wired to the Friedland transformer's 15V output - also had a 12V option - whereas 8V and 12V supplies seem much more common these days)? Maybe the old bell/chimes would work with a 12V feed?

Thanks in anticipation.
 
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One thing that is frequently overlooked is that the duty cycle of a transformer design to supply power to a door bell has to be very low. Supply the rated current continuously can result in a overheated and possibly failed transformer. A jammed on door bell or short circuit in the wiring can cause the transformer to over heat

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One thing that is frequently overlooked is that the duty cycle of a transformer design to supply power to a door bell has to be very low. Supply the rated current continuously can result in a overheated and possibly failed transformer. A jammed on door bell or short circuit in the wiring can cause the transformer to over heat

I take your point about duty cycle. I didn't think of checking the chime box, wiring and bell-push for a short circuit so will do that. Thanks.

One safety question I forgot to ask: should the transformer (primaries) be protected by a low-rated fuse? Maybe a preceeding fused spur, or similar, would have prevented the apparent burning of the old transformer and the blowing of a 5A fuse in the distribution unit? There was a fuse (still intact) on the output of the transformer which should, I imagine, have blown had the chime, wiring or bell-push shorted or jammed on.
 
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No the transformer should be internally protected either by a fuse or heat sensor. Fused spurs are not required on a lighting circuit and will have no discrimination anyway against a 6a MCB.
 

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