Moving this away from a thread

[winston1]

I pointed out a 2.5A one top of thread,

No you didn't. What you pointed out was a plug not a socket. Apart from the UK BS546 types the lowest rated SOCKET in use anywhere in the world seems to be 10 amps.

 

[EFLImpudence]

Well, as I'm sure you would agree, it's perfectly legitimate to have fuses ("etc.") protecting appliances (there are millions out there doing just that) but "we know what you meant to say" ( ), namely that the fuses which are there to protect cables should not also be expected to (necessarily) adequately protect appliances fed via those cables!

Yes, of course. Although I did say fuses etc. Not many products contain MCBs.
So how should I have described them so that everyone knew what I meant to say?

Perhaps we should call them 'cable fuses' or 'circuit fuses' so that their purpose is obvious.



Anyway, reading comments on this and other threads on the matter, it appears that some people think the reason for 'UK only' requirements is actually just kindness regarding electricians repairing fans in the dark and the convenience of householders.

Lots of things are good ideas but they should not be portrayed as regulations or mandatory requirements.

 

[EFLImpudence]

An oft quoted thing... But why not.

Because it is not not the purpose of circuit OPDs to protect appliances.
The circuit protection cannot be expected to be altered when different appliances are connected.
A socket circuit being the prime example.

Realistically why should an appliance not have a fuse in the plug or FCU etc to protect it?

Because if that is necessary then the product is not fit for purpose where such things are not available.

Indeed the MI for the cooker hood has called for a fuse of 3A, presumably to protect the thin cable but equally it protects the appliance too.

The cable won't be that thin, will it?
So the cable does not require 3A protection as is verified by it only having 16A protection elsewhere.

 

[ericmark]

Too many things being lumped together.

Fuses etc. are for protecting the cables, not appliances.

Since when? I expected better from you, we still today use fuses as they can act faster than a MCB, do remember we all talking about a fixed appliance, not portable.

It is too easy to forget a central heating system is not just one item the boiler, when you look at the thermostat it is often rated at 3A, the programmers as the same, it seems 3A is the industry standard for central heating items.

We have the same with lights, BS7671 may say 15A but most the ceiling roses are rated at 5A.

So we may consider a 6A MCB instead of 3A or 5A fuse, but 13A is going OTT. I will be first to admit some common sense is required and using 6A MCB instead of a 3A fuse may be acceptable, even when twice the size of the manufacturers recommendation. I have seen 4A MCB's but would see a problem with some makes of CU.

Be it using a 45A MCB for a 16A oven or 6A for 3A boiler we have to consider at what point to say that's going OTT, using 32A MCB for a 16A oven I would say OK, as 32A is the standard MCB used for cookers, so one 32A feeding a duel outlet cooker connection unit makes sense, 45A to my mind is going OTT.

We see the results of over sized overloads many times.

 

[winston1]

It is too easy to forget a central heating system is not just one item the boiler, when you look at the thermostat it is often rated at 3A, the programmers as the same, it seems 3A is the industry standard for central heating items.

Once again I point out to you that those same items are used Europe typically with the only OPD a 16a MCB, not your so called industry standard.

 

[ericmark]

Once again I point out to you that those same items are used Europe typically with the only OPD a 16a MCB, not your so called industry standard.

Since I can't read French, German, or any other European language I can't read there instructions to see if it asks for 3A or 16A supply, if other countries flaunt the instructions and use wrongly selected supplies that does not mean we should follow suit. There are many thermostats where 3A is moulded into the plastic, I really can't see the casting being different when supplied abroad.

 

[JohnW2]

So how should I have described them so that everyone knew what I meant to say?

You clearly know the answer to that, since you go on to write ...

Perhaps we should call them 'cable fuses' or 'circuit fuses' so that their purpose is obvious.

Indeed, if one were being pedanic (which is what seems to happen as regards language around here), that would be clearer. Similarly, if/when one is talking about 'plug fuses' (or 'fuses in plugs') the ideal is to say so explicitly.

Anyway, reading comments on this and other threads on the matter, it appears that some people think the reason for 'UK only' requirements is actually just kindness regarding electricians repairing fans in the dark and the convenience of householders.

Some people do think/suggest that but, even if it were the reason (which I very much doubt), I would still say that the 'MUST' in the instructions is way OTT (per your next comment, below).

Lots of things are good ideas but they should not be portrayed as regulations or mandatory requirements.

Definitely agreed - and, indeed, some of the things in documents which are (incorrectly) "portrayed as regulations or mandatory requirements" are not even 'good ideas' (in my opinion)!

However, at risk of stirring a constant source of disagreement, I would say that the 'MUST NOT'in relation to earthing exposed metal parts of a Class II item comes into a similar category!

Kind Regards, John

 

[EFLImpudence]

Since when?

Always?

I expected better from you, we still today use fuses as they can act faster than a MCB, do remember we all talking about a fixed appliance, not portable.

I do not see the difference between fixed or portable.
The portable will have a fuse in the plug but that is only because that is the only plug you have and for use on 32A circuits but even with this most of the fuses aren't really necessary.
I have no fuses in my plugs but the circuit is only 16A therefore the products must be designed for this.

It is too easy to forget a central heating system is not just one item the boiler, when you look at the thermostat it is often rated at 3A, the programmers as the same, it seems 3A is the industry standard for central heating items.

I have not forgotten.
Surely the 3A for thermostats is their maximum switching current. If the system does not draw more than that the circuit OPD is irrelevant - fault current in the cable being the only requirement.

We have the same with lights, BS7671 may say 15A but most the ceiling roses are rated at 5A.

If they never carry more than that then all is well - fault current in the cable being the only requirement.

So we may consider a 6A MCB instead of 3A or 5A fuse, but 13A is going OTT. I will be first to admit some common sense is required and using 6A MCB instead of a 3A fuse may be acceptable, even when twice the size of the manufacturers recommendation. I have seen 4A MCB's but would see a problem with some makes of CU.

That's not what the discussion is about. It is whether products which are fitted to 16A circuits require more protection solely because they have crossed the channel.

Be it using a 45A MCB for a 16A oven or 6A for 3A boiler we have to consider at what point to say that's going OTT, using 32A MCB for a 16A oven I would say OK, as 32A is the standard MCB used for cookers, so one 32A feeding a duel outlet cooker connection unit makes sense, 45A to my mind is going OTT.

There is no mention of OTT in BS7671; only whether compliant or not.

We see the results of over sized overloads many times.

Not on things which cannot cause (sufficient) overloads. I.e. those things designed for use on 16A circuits.

If I come back to England, will my new television be unsafe with a 13A fuse in its plug or must it have a 3A one? - It's only 70W; perhaps I must fit a 300mA fuse.

 

[ericmark]

There still seems to be a problem between portable and fixed.

I would agree some thing which is not fixed to the wall or floor and can be simply unplugged and plugged back in after moving to a different location should have any fuse required built into the appliance not the lead, be it a hair drier, or a steam cleaner on wheels, they are designed to be moved from location to location, and even the fridge/freezer is not in any way fixed to the location it is first used in, it can be moved house to house.

However we do not when moving home take the central heating system with us. It is well and truly fixed, it needs skilled people to install it, with a detailed installation commissioning procedure. It is well and truly fixed.

About the only other domestic appliance I can think of which is fixed in the same way is the immersion heater.

The pipe work, both for water distribution and bringing in and out combustion gases is rather involved, and in comparison the provision of an electric supply is small, however pre-wireless age it often involved cables between boiler, water store, programmer, and thermostat. So the running of a dedicated supply from the CU is a very small part of the whole install.

In the UK because of our ring final design we can easy provide a 3 amp fused supply for the boiler, likely outside the UK it would require a dedicated cable from the CU, but because our instructions in English are clearly for the UK, we don't know what the manufacturer asks for when being installed else where. If I do a hunt for installation instructions I will find them on for example https://www.worcester-bosch.co.uk and it is very clear from the web address these are for the UK, not Germany or France.

Since @EFLImpudence is not in the UK maybe he can direct us to Portuguese installation instructions so we can see first hand what is asked for there? I am sure 3A or 16A is shown the same what ever language so he should be able to point out the equivalent

as posted by @stem from the British instructions in this thread, or any of the other examples he gave, 3mm, 230 volt, Type A RCD and 3A is likely the same in any language so it should be easy enough to work out what it is saying.

I will watch for the reply with interest, and of course accept the results, but suspect that 3A is also asked for in Portugal as well as UK?

As a P.S. found Irish manual and it seems the Irish version has a 5A fuse inside the boiler which is not in the UK version.

 

[EFLImpudence]

There still seems to be a problem between portable and fixed.

Only to you.

I would agree some thing which is not fixed to the wall or floor and can be simply unplugged and plugged back in after moving to a different location should have any fuse required built into the appliance not the lead, be it a hair drier, or a steam cleaner on wheels, they are designed to be moved from location to location, and even the fridge/freezer is not in any way fixed to the location it is first used in, it can be moved house to house.

So, why would they not do it for fixed appliances?

However we do not when moving home take the central heating system with us. It is well and truly fixed, it needs skilled people to install it, with a detailed installation commissioning procedure. It is well and truly fixed.

So?

About the only other domestic appliance I can think of which is fixed in the same way is the immersion heater.

Do you think a 240V 3kW immersion will be alright on a 16A circuit or should it have a 13A (or 12A @ 230V) fuse?

The pipe work, both for water distribution and bringing in and out combustion gases is rather involved, and in comparison the provision of an electric supply is small, however pre-wireless age it often involved cables between boiler, water store, programmer, and thermostat. So the running of a dedicated supply from the CU is a very small part of the whole install.

Irrelevant - but why did they not used to do it, then?

In the UK because of our ring final design we can easy provide a 3 amp fused supply for the boiler, likely outside the UK it would require a dedicated cable from the CU, but because our instructions in English are clearly for the UK, we don't know what the manufacturer asks for when being installed else where. If I do a hunt for installation instructions I will find them on for example https://www.worcester-bosch.co.uk and it is very clear from the web address these are for the UK, not Germany or France.

Is physics different in those places?

Since EFLImpudence is not in the UK maybe he can direct us to Portuguese installation instructions so we can see first hand what is asked for there? I am sure 3A or 16A is shown the same what ever language so he should be able to point out the equivalent

as posted by stem from the British instructions in this thread, or any of the other examples he gave, 3mm, 230 volt, Type A RCD and 3A is likely the same in any language so it should be easy enough to work out what it is saying.

It's not the language that is the problem; it is the unavailability of the things that are stated on the UK instructions for the same product.

I will watch for the reply with interest, and of course accept the results, but suspect that 3A is also asked for in Portugal as well as UK?

Of course it isn't asked for. There are no 3A fuses. Note the instructions being discussed do not say it must be protected by a 3A OPD but specifically a fuse in FCU.

How can they demand things which do not exist?
Are you suggesting an extractor fan should have a dedicated 3A or less circuit MCB?

My boiler is just plugged into the socket circuit with a schuko plug.
Of course, it is difficult to prove a negative but here are the instructions. Note '3A' is the same in Portuguese.
https://vulcano-pt.resource.bosch.c...4_3/imesquentador_click_ventilado_wrd-kme.pdf

 

[bernardgreen]

There are no 3A fuses.

BS 1362 fuses

3 Amp
1 Amp
5 Amp

2 Amp and 7 Amp also available

 

[EFLImpudence]

You know perfectly well I meant in Europe for fitting in plugs or FCUs.

 

[JohnW2]

In the UK because of our ring final design we can easy provide a 3 amp fused supply for the boiler, likely outside the UK it would require a dedicated cable from the CU ...

Why? If 'outside of the UK' they felt that there were some appliances which needed an (externally) 3A-fused supply, they could have had things like our FCUs, fed from a 16A supply - but they don't seem to feel that there is a need.

Kind Regards, John

 

[ericmark]

It does seem 30 mA RCD only, it says
"
CAUTION: Thunderstorm! The device must have an independent connection to the electrical panel, protected by a 30 mA earth leakage circuit breaker. In areas with frequent thunderstorms, a thunderstorm protector must also be installed." followed by.

The device is equipped with a three-conductor cable (phase, neutral and earth) with a cross-section of 1.5 mm2 and a suitable plug. In this way, the socket to which it is connected must be earthed. Preferably, the circuit of these sockets should have a two-contact circuit breaker (phase + neutral).

Connection to electrical panel
If you want to connect directly to an electrical panel and need to replace the cable supplied with the water heater, you should do so with a similar cable, and preferably reserving a two-contact circuit breaker exclusive to the water heater in the panel. check that the appliance is properly grounded in the control box.

So it seems it does not ask for a fuse in Europe so installers are not going against any manufacturers instructions fitting European models with external fuse. And a hunt for English version quickly shows this boiler is not marketed in the UK, there is a different version for UK so what is required in Europe has no bearing as to what is required in UK they are different products.

 

[JohnD]

I wonder what a "thunderstorm protector" is?

edit

Wikipedia says it's a lightning conductor.

Rare in domestic houses in UK.

i wonder if tall street lamp poles do the job.