Are mains plug fuses really needed now?

Murmansk

I'm always puzzled when people refer to a plug as a plug top!? 

Then there's the way someone will be point to the sockets on the wall and say "there's a plug over there". Or maybe even a "plug socket"

Chrysalis

I have had a electrical device start smoking from overload although the trip box did eventually trip I think but not quickly.  Dont ask what caused it.

Also my consumer unit is hard to access, and requires an electrician for fiddling, far easier to swap a blown fuse in a plug.

grumbler

Risteard said:

MrsStepford said:

When I lived in Canada, the main itself was earthed, so none of the power sockets had switches or fuses, you just plugged them in. I was told that this is safer but I remain unconvinced. 

It's not necessary there or throughout most of the world because they don't have ring final circuits.

I think, it's an over-simplistic explanation. Why do we have, say, 5A fuses in some plugs?

And if this really were the case, it would make much more sense to have fuses in the sockets, not in the plugs.

It's not necessary there because there electrical safety standards are lower.

Risteard

grumbler said:

Risteard said:

MrsStepford said:

When I lived in Canada, the main itself was earthed, so none of the power sockets had switches or fuses, you just plugged them in. I was told that this is safer but I remain unconvinced. 

It's not necessary there or throughout most of the world because they don't have ring final circuits.

I think, it's an over-simplistic explanation. Why do we have, say, 5A fuses in some plugs?

And if this really were the case, it would make much more sense to have fuses in the sockets, not in the plugs.

It's not necessary there because there electrical safety standards are lower.

It's not overly simplistic - it's the simple fact of the matter.

Because of this, however, there can also be smaller flexes with a lower capacity fuse.

Incidentally, 5A is not a standard size - only 13A and 3A are.

It has nothing to do with other standards being lower, which is an incredibly arrogant comment to make. Most of the world consider the concept of a ring final circuit to be fundamentally reckless. (I don't agree if designed and installed correctly, verified correctly and maintained correctly.)

grumbler

twopenny said:

Since a lightening strike blew all the routers in the area, was said by the phone line, but the fuse in the surge socket for my laptop plug seemed to keep it safe I'm not taking any chances

What fuse and why do you think it kept it safe?

The routers were supposedly blown by a surge in the phone line.

grumbler

Risteard said:

grumbler said:

Risteard said:

MrsStepford said:

When I lived in Canada, the main itself was earthed, so none of the power sockets had switches or fuses, you just plugged them in. I was told that this is safer but I remain unconvinced. 

It's not necessary there or throughout most of the world because they don't have ring final circuits.

I think, it's an over-simplistic explanation. Why do we have, say, 5A fuses in some plugs?

And if this really were the case, it would make much more sense to have fuses in the sockets, not in the plugs.

It's not necessary there because there electrical safety standards are lower.

It's not overly simplistic - it's the simple fact of the matter.

So far it's a fact only because you say so without explaining why. I don't see any relation between ring circuits and fuses in plugs. I can plug several powerful devices in one ring - they will trip the MCB, but the fuses will remain intact.

The fuse protects the cable wired into it - this is the only fact that makes perfect sense to me.

FFHillbilly

1. ring final circuits are rated at 32A.
2. cable flexes for most appliances are rated around 16A
3. radial circuits in Europe and USA are 15/16A

the purpose of the plug fuse is to protect the cable in the appliance, so they are required for a 32A ring circuit, but if the circuit is rated at 16A thats the same as the appliance and a second fuse is pointless.

that could be over simplifying too...

chrisw

I would say 'most' houses in the UK still have the older wired fuse box. Our estate does and it was only built in 1990.

Section62

grumbler said:

Risteard said:

grumbler said:

Risteard said:

MrsStepford said:

When I lived in Canada, the main itself was earthed, so none of the power sockets had switches or fuses, you just plugged them in. I was told that this is safer but I remain unconvinced. 

It's not necessary there or throughout most of the world because they don't have ring final circuits.

I think, it's an over-simplistic explanation. Why do we have, say, 5A fuses in some plugs?

And if this really were the case, it would make much more sense to have fuses in the sockets, not in the plugs.

It's not necessary there because there electrical safety standards are lower.

It's not overly simplistic - it's the simple fact of the matter.

I don't see any relation between ring circuits and fuses in plugs.

A ring final circuit is a system.

A requirement of installing a ring final circuit is the use of accessories (e.g. socket outlets) complying with BS1363.  BS1363 accessories are designed to use a fuse complying with BS1362.

Hence you can't (legally) install a domestic final ring circuit which doesn't make use of BS1362 fuses, either in the plugtop or in the accessory.

That is the simple fact of the matter.

The reason why is that in the UK (and some other countries) we have opted for a system using a higher capacity final circuit (e.g. designed for protection by a 30/32A fuse/MCB) with the required lower level of protection (e.g. 3A / 13A) located at the point the appliance connects to the final ring circuit.

Elsewhere in the world the final circuits are designed with a lower capacity and the protective device (e.g. 15 or 16A) is located at the consumer unit.  Hence they have no need for plugtop fuses because the consumer unit is providing the required level of protection.

Prior to the UK adopting the '13A plug', we used a similar domestic system involving unfused round-pin plugs of (generally) 2A, 5A or 15A capacity.  In theory these 15A plugs would be used with circuits protected by a 15A fuse at the consumer unit, 5A plugs on a circuit protected by a 5A fuse (quite often a spur from a lighting circuit).  The theory didn't really represent practice though, which is one of the reasons why the standardised system of BS1363 was introduced - all plugtops would be the same and could be used in any BS1363 socket, only the fuse rating needed to be correctly selected.

grumbler

Section62 said:

grumbler said:

Risteard said:

grumbler said:

Risteard said:

MrsStepford said:

When I lived in Canada, the main itself was earthed, so none of the power sockets had switches or fuses, you just plugged them in. I was told that this is safer but I remain unconvinced. 

It's not necessary there or throughout most of the world because they don't have ring final circuits.

I think, it's an over-simplistic explanation. Why do we have, say, 5A fuses in some plugs?

And if this really were the case, it would make much more sense to have fuses in the sockets, not in the plugs.

It's not necessary there because there electrical safety standards are lower.

It's not overly simplistic - it's the simple fact of the matter.

I don't see any relation between ring circuits and fuses in plugs.

A ring final circuit is a system.

A requirement of installing a ring final circuit is the use of accessories (e.g. socket outlets) complying with BS1363.  BS1363 accessories are designed to use a fuse complying with BS1362.

Hence you can't (legally) install a domestic final ring circuit which doesn't make use of BS1362 fuses, either in the plugtop or in the accessory.

That is the simple fact of the matter.

The reason why is that in the UK (and some other countries) we have opted for a system using a higher capacity final circuit (e.g. designed for protection by a 30/32A fuse/MCB) with the required lower level of protection (e.g. 3A / 13A) located at the point the appliance connects to the final ring circuit.

Elsewhere in the world the final circuits are designed with a lower capacity and the protective device (e.g. 15 or 16A) is located at the consumer unit.  Hence they have no need for plugtop fuses because the consumer unit is providing the required level of protection.

Prior to the UK adopting the '13A plug', we used a similar domestic system involving unfused round-pin plugs of (generally) 2A, 5A or 15A capacity.  In theory these 15A plugs would be used with circuits protected by a 15A fuse at the consumer unit, 5A plugs on a circuit protected by a 5A fuse (quite often a spur from a lighting circuit).  The theory didn't really represent practice though, which is one of the reasons why the standardised system of BS1363 was introduced - all plugtops would be the same and could be used in any BS1363 socket, only the fuse rating needed to be correctly selected.

References to regulations and history don't support your original statement "because they don't have ring final circuits". At least I don't see any logic in this explanation and you didn't address the points I raised in my previous point.
"Elsewhere in the world" not all appliances have cables with 15A capacity, e.g. desk lamps. As a result,  15A devices located at the CU don't provide "the required level of protection". What's "required" and why "they have no need for [fused] plugtop"? My answer is  that it's because the requirements (safety standards) are different.