What is this plug socket for?!

[David Hansen]

On Sun, 27 Aug 2006 21:01:08 +0100 someone who may be "Jerry" wrote this:-

That is irrelevant to your assertion, because there is the same risk of someone doing that, no matter how the final circuits are wired.

You are basing your assertion on different types of protective device being used for different types of final circuit. However, that is false. With the exception of a standard 30/32A radial circuit, any type of protective device may be used on any type of circuit. Each sort of protective device may be abused in various ways, for example a Wylex style MCB can have a wire wrapped round the pins.

Excellent, more personal abuse. Such abuse is usually the resort of those who don't have better arguments.

Do you normally run the leads of freezers and fish tanks into another room? Do you think this would be a good idea if each room had a radial circuit supplying all the sockets in that room?

Only a fault in the fixed wiring. Such faults rarely just happen, they are usually caused by humans doing things like drilling into the cable.

Easily? Well someone could use the wrong fuse. However, even if they do a 13A fuse near the appliance will protect it far more than say a

20A fuse at the consumer unit. If the radial circuit has a 30/32A protective device then there is no difference to a ring circuit with the same protective device.

I note that we are still waiting for an answer as to whether your objection is to individually fused appliances or fixed wiring systems. Unless you answer that question I might soon conclude that you are trolling.

If the protective device fails to operate. Time, as well as current, determines what is dangerous.

The same is true of radial circuits of course. If the protective device does operate other then once in a blue moon then the designer has failed to make a suitable allowance for diversity, whether the circuit is radial or a ring.

[David Hansen]

On Sun, 27 Aug 2006 21:05:30 +0100 someone who may be "Jerry" wrote this:-

You are the one who seems to be doing that.

Believe that if you like.

Ah, mind reading. Added to the personal attacks that paints an interesting picture.

Ah, now we are talking about cartridge fuses, not rewirable fuses. I note the twisting and turning.

Is an MCB slower than a cartridge fuse? The answer is that usually it is, assuming we are comparing devices of the same rating and type of duty at the same short-circuit current. Thinking that an MCB operates more quickly than a cartridge fuse is a common misconception, but it is still a misconception. All the fuse element has to do is melt, a rapid operation at high currents. By contrast the magnetic coil of an MCB has to operate several mechanical linkages, with their attendant friction and inertia, to move the contacts far enough apart to quench the arc. That is assuming that it can quench the arc.

The situation in which an MCB may operate more quickly than a cartridge fuse is a relatively small overcurrent of long duration, when the thermal trip of an MCB may operate before a fuse does. However, such a situation is to do with a poor estimation of diversity and hence the protection of the fixed wiring from overload, rather than the protection of appliances and their wiring that you were talking about.

That is comparing protective devices at the same position, so one is just comparing the speed of operation at particular currents. Discrimination between protective devices of different types and ratings at different positions is far more complicated. However, until you say whether you want a fuse in the plug or not that sort of discussion is not worth entering into.

[Dave Plowman (News)]

It would if you had only one radial. As very few properly wired houses have only one ring.

What maintenance is required on a ring? And surely no one fits a socket/switch at a cooker these days?

An appliance failing doesn't take out the ring - that's what the plug fuse is for. It would take out a radial, though.

[Jerry]

,

circuit

houses

Who said anything about just haveing one radial circuit? As for ring circuits, many properly wires but badly desinged (read cheaply specified) houses do only have one ring IME. Of couse larger houses will have often have more than one ring circuit due to 'diverstiy' failings...

circuit

Err, what if you want to add / replace a outlet or (dis) connecting an appliance from a FCU that is on a ring circuit for example? I also expect that many people do still fit combined cooker/socket plates, be that new or replacement.

re-supplied.

It doesn't normally take out the ring protection but it can and most certainly would if the BS1363 plug device has been compromised (assuming it doesn't burn the house down first...), yes it would take out radial circuit but it would only take out those appliances on that circuit, not half (or more) of the appliances in the house.

[Jerry]

No, you are doing that, you have taken a single (admittedly badly worded) sentence out of it's context. The context to the remark has and always was about the type of fuse fitted to a BS1363 plug.

[Dave Plowman (News)]

It's a fair assumption with common goalposts. Radial circuits cost more than rings for a given number of sockets, so if penny pinching applies to one it should to the other.

As I said, penny pinching. Which can apply to radials too.

You do this every day? But then the same applies to a radial if feeding more than one outlet, which most do.

Doesn't make it good practice, though.

You can make things fool proof. Idiot proof. But not c**t proof. If someone replaces a plug top fuse with a non fusible link they deserve to die a horrible death...

I'd guess you've worked in too many back street car repair places with arc welders...

All you need to look at is the practical implementation of radials in other countries. They are far more likely to be overloaded by the addition of extra outlets. Oh - and the 'fusing' altered to 'cope'. We're not alone in having idiots to deal with.

[Andrew Gabriel]

You do seem to have a compulsive obsession with a circumstance which just doesn't exist in real life. If you really want to discuss improving wiring, start by looking at real problems rather than non-problems, as attempting to solve non-problems gets you at best, nowhere.

[Jerry]

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applies to

So this is coming back to cost rather than what is better, rings are cheaper than radials, that doesn't mean they are better.

cooker/socket

In some small kitchens replacing a combined cooker/socket pale with a cooker only plate will could remove 1/4 to 1/3 the number of sockets in the kitchen! It might not be good practise but it could well be the only valid practise short of a partial rewire...

section of

re-supplied.

deserve to

Indeed, but what of their family who are innocent, what about those who will risk their lives to attempt rescue?

Wash you mouth out with battery acid!

FYI I've never worked in any back street place, and as for arc welders - havn't seen one, let alone used one, since my college apprentership days many years ago...

Yes, cowboys work in all industries and all countries, the determined DIY idiot will never be defeated but the problem with the BA1363 plug is that it's been designed to be 'reparable' without any more knowledge that how to use a screwdriver.

[Jerry]

I must admit that since the law made it compulsory for all new appliances - that need a BS1363 plug - come fitted with a correctly installed plug (and protection), the problem has decreased, before it was not uncommon for appliances to be fitted with incorrect protection (even if the plug was correctly wired...).

[Guy King]

The message from "Jerry" contains these words:

Many years ago Mum bought a washing machine from Currys. It was delivered and they made a big thing about having put a plug on it for her. None of the conductors had been cut to length and the cable was on top of the grip. At least they had got a 13A fuse in it.

I cut it off and took it into the shop and they didn't seem at all bothered. Perhaps being only about 12 didn't help.

[David Hansen]

On Mon, 28 Aug 2006 10:14:08 +0100 someone who may be "Jerry" wrote this:-

I note that you did not respond to my long piece on the comparative operating times of MCBs and cartridge fuses.

My impression is confirmed, you are trolling.

[Jerry]

Becase I have already answered that within the thread.

Pot, kettle, black.

[John Rumm]

Not convinced that is true. Much depends on what abuse you are thinking about. If you eliminate the fused protection in the plug then even a 20A Type B MCB protected radial will deliver 40A for three minutes. Just how long does your skinny 0.5mm flex take to melt and cause a fire?

Ring final circuits are not a panacea for all ills, but they are certainly the best solution for general power distribution round a house. Both theory and practice demonstrate this. This does not suggest that radials do not have a place. Far from it, there are situations where they are better suited. To argue that one is simply "better" without qualifying the circumstances is just nieve.

This is a situation where the provision of a dedicated non RCD protected radial circuit for these appliances would be appropriate. It in no way invalidates the practice of using a ring circuit for general power provision.

The other point to realise is that even if you have half a dozen radials providing power to the house, a RCD trip at the CU due to a fault on one will still take out *all* of them.

Yup, pretty much all of them...

How often do you see surge protection oncorporated at a CU? or that matter how often is surge suppresion much use in the first place (compared to a line interactive UPS)?