i had to connect a wireless room stat into a boiler this morning, i forgot to look at the make but it had what looked like 2 2amp fuses fitted internally. 1 on the line and 1 on the neutral. not something ive seen before, boiler is 12months old. Is this common practice ?

Gary

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Specialised Subject. The Bleedin Obvious. John Cleese

I suspect so - I'm pretty sure the Vaillant I had quite a few years ago was d.p. fused internally too. Probably to cover some continental markets where the supply isn't reliably polarised with an earthed N (e.g. connected via a non-polarised plug & socket)

A lot of appliances are often have s.p. switching in N internally these days (e.g. a fan-heater with the selector switch in one pole and the thermostat in the other). Normally it isn't a problem as both L and N are treated as live internally anyway.

It might be a slight concern with a boiler that might have external wiring to thermostats, valves, pumps and so on fed from the d.p. fuses and the old 'looks dead but could be live' scenario. I think most people wouldn't rely on an apparently blown fuses as a means of safe isolation these days and you won't have the equivalent of the old radiant heaters where the element could be touched, so I doubt it's a big problem in reality.

- Andy.

thanks for the reply Andy.
Its a combi boiler with pump built in so nothing external except for the wireless receiver i have just fitted.


Gary

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Specialised Subject. The Bleedin Obvious. John Cleese