13a Fused single socket advice

[mcdermottc]

Ideally, the fused connection units and switches above the worktop should not have been installed in the first place.

Aren't all new build houses installed this way now ? I'd hate to have to drag out a washing machine full of water and clothes for a blown fuse so maybe there is some sense in the method.

Anyway i'm moving so don't really care now lol

Winston I'd read a fridge only needed a 3amp fuse in any case the fuse will be in their plug so not worried.

thanks for everyones input.

 

[winston1]

Ideally, the fused connection units and switches above the worktop should not have been installed in the first place.

Aren't all new build houses installed this way now ? I'd hate to have to drag out a washing machine full of water and clothes for a blown fuse so maybe there is some sense in the method.

Anyway i'm moving so don't really care now lol

Winston I'd read a fridge only needed a 3amp fuse in any case the fuse will be in their plug so not worried.

thanks for everyones input.

If the fuse blows it is for a reason and no doubt a replacement will blow unless you drag out that machine and fix the fault.

What you read was wrong. The fuse is to protect the cable not the appliance. No fridges have cables rated at only 3A.

 

[mcdermottc]

Ideally, the fused connection units and switches above the worktop should not have been installed in the first place.

Aren't all new build houses installed this way now ? I'd hate to have to drag out a washing machine full of water and clothes for a blown fuse so maybe there is some sense in the method.

Anyway i'm moving so don't really care now lol

Winston I'd read a fridge only needed a 3amp fuse in any case the fuse will be in their plug so not worried.

thanks for everyones input.

If the fuse blows it is for a reason and no doubt a replacement will blow unless you drag out that machine and fix the fault.

What you read was wrong. The fuse is to protect the cable not the appliance. No fridges have cables rated at only 3A.

Here is the weblink

http://www.electricalsafetyfirst.org.uk/guides-and-advice/electrical-items/plugs/

Thanks again

 

[winston1]

Ideally, the fused connection units and switches above the worktop should not have been installed in the first place.

Aren't all new build houses installed this way now ? I'd hate to have to drag out a washing machine full of water and clothes for a blown fuse so maybe there is some sense in the method.

Anyway i'm moving so don't really care now lol

Winston I'd read a fridge only needed a 3amp fuse in any case the fuse will be in their plug so not worried.

thanks for everyones input.

If the fuse blows it is for a reason and no doubt a replacement will blow unless you drag out that machine and fix the fault.

What you read was wrong. The fuse is to protect the cable not the appliance. No fridges have cables rated at only 3A.

Here is the weblink

http://www.electricalsafetyfirst.org.uk/guides-and-advice/electrical-items/plugs/

Thanks again

Well it is wrong. As I said the fuse is to protect the cable not the appliance. If an appliance needs protection it will be fitted internally. Many items have a switch on surge greater than its normal operating current which will blow a 3A fuse.

 

[ericmark]

Well it is wrong. As I said the fuse is to protect the cable not the appliance. If an appliance needs protection it will be fitted internally. Many items have a switch on surge greater than its normal operating current which will blow a 3A fuse.

Not quite true. For portable appliance yes fuse is for cable. But for a fixed appliance manufacturers can stipulate protection required. For example most shower units say must use RCD protection.

As to fridge/freezer mine has a maximum draw of 110W on defrost start and run more like 60W. However those without three phase motors and inverter drives will have a higher start current could be as much as 10A. As to if for such a short time it would rupture a 3A fuse is another question.

The brown (previously red) plug wire goes to live (L).

No it goes to the Line (L). Clearly rather an old website, mixer, blender, fridge, freezer, power drill, jig saw all may exceed 700W (Actually 690W = 3A) and toaster, iron are often under 690W. A cordless smoothing iron yes often over 690W but otherwise often under 690W my gran would plug hers into the lights which was common in 1950's.

The point about plug or FCU is really down to cooling of the plug. Where there is free air then using a plug and socket is great. But where there is little free air then the FCU cools through the wall so has far less of a problem with overheating. I always remember the hand drier in the toilet. Trying to PAT test was a nightmare turn off power and fit MCB lock, remove whole hand drier take to workshop and PAT test and then replace. Glad one once every 4 years.

For DIY the FCU is no problem but for the maintenance man it's a real problem. If house is TN-C-S OK just lock on MCB if you have frame to fit the lock to that make MCB. Health and Safety at work act will not allow working live so power must be cut before removing FCU. OK there is a grid switch, but unless you can lock it off then no good. With TT has to be main isolator again there is a problem finding a device to be able to lock off. So you call the fridge/washer man he sees no plug as says that's £60 please and sorry I am not allowed to work on it.

So on balance I would say plug and socket every time. I agree up to the buyer to change them but I understand why he wants to plug items in.

 

[EFLImpudence]

For portable appliance yes fuse is for cable.

Right.

But for a fixed appliance manufacturers can stipulate protection required.

Why, what's the difference?

For example most shower units say must use RCD protection.

They are just stating the electrical regulations for personal protection.
The RCD does nothing for the appliance.

 

[ericmark]

When I have a large piece of machinery it is common for the MCB, fuse, or other protective device to be installed were one has easy access. The position will depend on the building so in one building could be to right and another to left of the operators position. It is common to not get the whole machine from one supplier and to be required to buy and install the protective devices outside of the main unit.

As a result the rules for portable appliances does not extend to fixed appliances there is no requirement with a fixed appliance for the manufacturer to include protection within the unit if required. He can simply tell the installer what protection is required. So in domestic for example it is OK for a cooker manufacturer to say this item must be protected by a 32A over current device and should the consumer unit have a 45A device it is the responsibility of the installer to change it.

Where the problem arises is in deciding what items are portable. Fridge, Freezer, washer, dryer, dishwasher will all simply plug in so we would normally consider as portable but they are also all over the weight limit and although some have wheels looking at the inspection and testing of in-service electrical equipment they would all be classed as not portable. As to wheels well the batching plant I worked one was on wheels it came on 24 wagons as trailers and when finished would go to next site. But one would not consider it as really portable and with a 200A supply you did not simply plug it in. It did however have many plugs and sockets to enable easy installation which of course we did not cut off.

 

[EFLImpudence]

When I have a large piece of machinery it is common for the MCB, fuse, or other protective device to be installed were one has easy access. The position will depend on the building so in one building could be to right and another to left of the operators position. It is common to not get the whole machine from one supplier and to be required to buy and install the protective devices outside of the main unit.

We are talking about someone who wants an FCU changed to a socket and domestic appliances.

As a result the rules for portable appliances does not extend to fixed appliances there is no requirement with a fixed appliance for the manufacturer to include protection within the unit if required.[

I don't know about requirements but that is not the case - boilers, for example, have fuses.

He can simply tell the installer what protection is required.

Do you have an example?

So in domestic for example it is OK for a cooker manufacturer to say this item must be protected by a 32A

But they don't.

over current device and should the consumer unit have a 45A device it is the responsibility of the installer to change it.

Not if the cables is rated for that.

Where the problem arises is in deciding what items are portable.

Not a problem here - and again, what difference does it make?

 

[ericmark]

A standard immersion heater does not have a current fuse built in. It may have an over temperature fuse but not current. It relies on the supply some where having a 13, 15, 16 amp fuse or MCB.

Be it a fridge, freezer, washing machine or any other item normally fitted with a 13A plug then in the main any over current protection will be built in and the fuse is only to protect the cable so in the UK we can use thinner cable than in rest of Europe as a 3A fuse can be fitted to the plug. In theroy however in real terms equipment for UK and Europe is the same only the plug changes.

I am sure you like myself have at some time checked the fuse found it missing or blown replaced it only for it to blow with a large bang. Clearly there was no internal overload protection. Does not matter how many times you say is should have it built in clearly not all manufacturers follow the rules.

There is nothing to stop you with an old loadmaster consumer unit fitting a 60A MCB and using 16mm² to feed a junction box for the cooker. But should one of the spade connectors become loose and overheat the cable will fail and likely destroy all the wiring in the cooker before the MCB trips and it could well be the case that the earth wire can't take 60A. Cookers were for years 32A even using 45A may mean internal earth wires are not thick enough.

My cooker can use 12455 W at 240 volt that's around 52A but manufacturers instructions say 32A supply. I have never tripped the 32A MCB.

Simple facts no one wants any hand tool going bang in their hands even if when it goes bang there is no danger to the user. So using a fuse in the plug of a size where the fuse goes bang rather than the appliance going bang makes sense what ever the rules say about fuse in plug being for the cable. I have un-fused adaptors which in my case are always fitted to an extension lead so are fused. But plugging one of these adaptors into a 13A outlet then using a German plug into the adaptor means that equipment has just a B32 MCB as protection. For items like table lamps this would break 559.6.1.6 as over 16A in fact the isolation rules also limit to 16A over that you need a switch a plug and socket on it's own is not good enough. Government defines portable as 10 kg or lighter. Being “can be hand-carried by an average person without difficulty”. The washing machine weight is 10 kg without the weight of the machine.

 

[JohnW2]

A standard immersion heater does not have a current fuse built in. It may have an over temperature fuse but not current. It relies on the supply some where having a 13, 15, 16 amp fuse or MCB.

Why does an immersion heater need overload protection at all? Can you envisage any situation in which an immersion heater could result in a overload (as opposed to a fault) situation?

Kind Regards, John

 

[EFLImpudence]

A standard immersion heater does not have a current fuse built in. It may have an over temperature fuse but not current. It relies on the supply some where having a 13, 15, 16 amp fuse or MCB.

As above.

Be it a fridge, freezer, washing machine or any other item normally fitted with a 13A plug then in the main any over current protection will be built in and the fuse is only to protect the cable so in the UK we can use thinner cable than in rest of Europe as a 3A fuse can be fitted to the plug. In theroy however in real terms equipment for UK and Europe is the same only the plug changes.

Ok.

I am sure you like myself have at some time checked the fuse found it missing or blown replaced it only for it to blow with a large bang.

Wouldn't that be fault current?

Clearly there was no internal overload protection. Does not matter how many times you say is should have it built in clearly not all manufacturers follow the rules.

If that is the case, I would therefore conclude it does not require overload protection.

There is nothing to stop you with an old loadmaster consumer unit fitting a 60A MCB and using 16mm² to feed a junction box for the cooker. But should one of the spade connectors become loose and overheat the cable will fail

Would that be overload?

and likely destroy all the wiring in the cooker before the MCB trips and it could well be the case that the earth wire can't take 60A. Cookers were for years 32A even using 45A may mean internal earth wires are not thick enough.

The internal wiring of a cooker is not capable of carrying 32A - likely 1.5mm² at most - ...
... but none of them will have to as each element is separate and cannot overload.

My cooker can use 12455 W at 240 volt that's around 52A but manufacturers instructions say 32A supply. I have never tripped the 32A MCB.

32A protects the cable. It could be 45A now (method C) since the demise of BS3036s .

Simple facts no one wants any hand tool going bang in their hands even if when it goes bang there is no danger to the user. So using a fuse in the plug of a size where the fuse goes bang rather than the appliance going bang makes sense what ever the rules say about fuse in plug being for the cable.

I think you are confusing fault and overload again.

I have un-fused adaptors which in my case are always fitted to an extension lead so are fused. But plugging one of these adaptors into a 13A outlet then using a German plug into the adaptor means that equipment has just a B32 MCB as protection.

So?

For items like table lamps this would break 559.6.1.6 as over 16A in fact the isolation rules also limit to 16A

Is there a similar regulation for appliances?

over that you need a switch a plug and socket on it's own is not good enough. Government defines portable as 10 kg or lighter. Being “can be hand-carried by an average person without difficulty”. The washing machine weight is 10 kg without the weight of the machine.