Nest Thermostat Y-Plan Install

Boilers in Europe are invariably plugged into the standard socket for the country
which very often is connected to a 6 ( six ) amp MCB in the consumer unit or a 5 ( five ) amp bottle top fuse.

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@stem I seem to have caused quite a debate haha... I'll certainly be changing the fuse to 3A.

Just to add to the debate, wouldn't going against manufacturers specifications void it's warranty?
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Back in the UK, boiler warranty terms usually include a statement along the lines of that the installer "must complete the Benchmark commissioning checklist". This checklist includes the statement that "the boiler and associated products have been registered with Gas Safe and installed and commissioned in accordance with the manufacturers instructions" to which the installer is required to tick a box marked 'Yes' [there isn't a 'no' option]

Based on that if they wanted to, I suppose a boiler manufacturer might try to wriggle out of the warranty if the manufacturers instructions say that a 3A fuse should be fitted to the boiler and it wasn't.
I remember the bottle fuse, did not like the switch being after the fuse, but did like the way the base could be changed so over size fuses would not fit. In Turkey in the hotel each room had a consumer unit with MCB's and relays and even in UK pre-war every socket had it's own fuse, so actually more fuses pre-war than MCB's today in British homes.

However does it really matter what is done in Europe? We live in the UK and really I don't care what they do, we do it the safe way. Just because some daft twit in some country walks on fire, it does not mean I need to copy them.

Having worked around the world I have seen the other methods, Flanders and Swann had the right idea
The English, the English, the English are best
I wouldn't give tuppence for all of the rest
Winston and I are not talking about wriggling out of warranties by any excuse available nor nostalgic jingoistic attitudes but actual electrical requirements for the appliances.
Unless there is a fault, you could supply an appliance with a 1000 amp fuse even if it only needs one amp and it will work OK. The fuse/MCB/RCBO/RCD are only required when there is a fault, the idea is, when there is a fault, the easy to replace or reset protective device removes the supply automatic without causing damage to the system.

So to work out protective device size, we need a risk assessment as to what can go wrong causing over current. So if a stalled motor will burn out, we set the protective device as a current less than the stall current, but higher than run current.

So on central heating although the motorised valve stalls, it is designed to stall, so does not need protection from that, fans and pumps in the boiler use a very low current, so to protect them a fuse much lower than 3 amp would be required. So in real terms I personally can't see why a 3A fuse would be fitted? Only time I have seen the fuse rupture is because some one has fiddled with wiring in some way, be it drill through a cable or make wrong connections, and it can be said we don't need to protect against some one doing something silly, it is up to people not to do anything silly.

However where ever we live, we are brought up to expect a certain level of protection against doing silly things, and if we don't follow the convention of that country then we get danger, so if for example all safety switches are red or yellow and we find a black switch we do not consider removing that switch will cause danger, but we would not dream of removing a red or yellow switch. So if some one use to UK working practice works on a German machine where the safety switch is black, then as happened to me, one can be involved in an accident that means you never work again.

So since in this country we should fit type A RCD and a 3A fuse in a FCU that is what we should do, and it does not matter one little bit what the daft Germans do.
Not a 3amp one then? Once MI would not be satisfied!

I didn't make a habit of inspecting people's boilers and their electrical supply when I was living in Germany, That said I do recall that 1 amp, 2 amp and 3 amp inserts for bottle tops were available.

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