Wiring remote switched sockets for Kitchen appliances

[echoes]

To be absolutely clear you are wrong. The fuse is to protect the cable not the appliance which should be internally protected. Appliances are sold all over the world and most of it does not have fused plugs and rely on the MCB or fuse in the CU which in Europe is usually 16 amp.

Assuming a 32 A MCB in the CU, standard ring.

So if a lowish power (e.g. small fridge) appliance flex was wired directly into an FCU, which is electrically no different to using a cable + flex outlet, what rating fuse should go in the FCU?
And if separate flex outlet was used, what size fuse?
I'll gratefully accept corrections.

 

[winston1]

So if a lowish power (e.g. small fridge) appliance flex was wired directly into an FCU, which is electrically no different to using a cable + flex outlet, what rating fuse should go in the FCU?
And if separate flex outlet was used, what size fuse?
I'll gratefully accept corrections.

As the fridge is probably sold in other EU countries its flex must be rated sufficiently to be used on a 16 amp MCB. As the only official BS1363 fuses are 3 or 13 amp it has to be a 13 amp, as a 3 amp could blow on start up surge.
The fridge should have its own internal protection anyway.

 

[ban-all-sheds]

It is a proven design that has been in use since before you were born.

So is the radial.

Any chance you could break with the habit of a lifetime and have an important, or even useful, point to make?

 

[winston1]

So is the radial.

Any chance you could break with the habit of a lifetime and have an important, or even useful, point to make?

That was a useful point.

 

[ban-all-sheds]

In what way?

How does pointing out that a standard circuit type has been around for a long time qualify as a useful point to make wrt wondering if it is necessarily the best type to use?

 

[echoes]

As the fridge is probably sold in other EU countries its flex must be rated sufficiently to be used on a 16 amp MCB. As the only official BS1363 fuses are 3 or 13 amp it has to be a 13 amp, as a 3 amp could blow on start up surge.
The fridge should have its own internal protection anyway.

Understood.
Now a real example. I have a plinth heater. MIs state explicitly to use an FCU with a 3A fuse. Mine is connected via a separate flex outlet plate. Should I use a 3A fuse, and what is that fuse protecting?

 

[ban-all-sheds]

What you should do as a matter of urgency is to write to the maker and ask him why he specifies that fuse.

You may find, given his answer, that you should not touch his flaky product with a bargepole.

Is it sold elsewhere in Europe?

 

[JohnW2]

A ring would be a sound choice if a 4mm radial was unsuitable (e.g. voltage drop, installation method) ...

That latter point is, IMO an important point which I think sometimes gets overlooked, particularly by those people who commonly advocate 4mm² radials rather than rings. However, whilst there's not an awful lot of difference between the VD with the two (the small difference being in favour of the ring), a 4mm² 32A radial is only possible with Method C installation, whilst a 2.5mm² 32A ring is OK with most common installation methods.

Kind Regards, John

 

[winston1]

Understood.
Now a real example. I have a plinth heater. MIs state explicitly to use an FCU with a 3A fuse. Mine is connected via a separate flex outlet plate. Should I use a 3A fuse, and what is that fuse protecting?

Manufacturers instructions are guidance only and don't need to be followed, especially when they are wrong. I assume this plinth heater is sold throughout the EU where FCUs are not available or compliant.

If they are suggesting a 3 amp fuse I assume this heater has 0.5mm cable on it and is rated at less than 720 watts. Both would seem unlikely and the cable would be non compliant.

The MI are clearly wrong in this case.

 

[echoes]

What you should do as a matter of urgency is to write to the maker and ask him why he specifies that fuse.

You may find, given his answer, that you should not touch his flaky product with a bargepole.

Is it sold elsewhere in Europe?

No idea.
So is there *ever* a valid case for putting a 3A fuse in an FCU, given the European market assumptions?

 

[JohnW2]

So is there *ever* a valid case for putting a 3A fuse in an FCU, given the European market assumptions?

I suppose that depends upon whether one regards European practices as being adequately 'safe' in the eyes of those in the UK.

Kind Regards, John

 

[echoes]

Manufacturers instructions are guidance only and don't need to be followed, especially when they are wrong. I assume this plinth heater is sold throughout the EU where FCUs are not available or compliant.

If they are suggesting a 3 amp fuse I assume this heater has 0.5mm cable on it and is rated at less than 720 watts. Both would seem unlikely and the cable would be non compliant.

The MI are clearly wrong in this case.

It's certainly much less than 720W. Just a small motor (heat via central heating).
I *think* flex is either 0.75 or 1mm.
Perfectly possible that UK MIs are too conservative.

 

[EFLImpudence]

Perfectly possible that UK MIs are too conservative.

I don't think it's a question of conservative, as such; it's just what they do because they can.

The same as some "instructions" have been discovered to have been written by the Marketing Department of one well known company.

Fan instructions, which frequently call for a 3A fuse, also call for a 3 pole isolator; neither of which is required electrically for the fan.

 

[JohnW2]

The same as some "instructions" have been discovered to have been written by the Marketing Department of one well known company.

Actually arguably 'worse' than that - it was "Technical Data Sheets" that I was told (by a Technical guy) were largely written by the Marketing Dept!

Kind Regards, John

 

[echoes]

There is no argument against fuses, whether in plugs or FCUs, protecting the downstream cable and/or flex, rather than the appliance.

Given what has been said about suitability for foreign markets and 16A OPDs, I'm struggling to follow that logic to a point where any fuse other than 13A is required.

In the meantime, I'll continue to choose fuses based on the power of the connected appliance.