What is this plug socket for?!

[David Hansen]

On Sun, 27 Aug 2006 10:35:04 +0100 someone who may be "Jerry" wrote this:-

Fridges and freezers don't really "benefit" from dedicated supplies, in most circumstances. The one circumstance where there might be benefit is where an over-enthusiastic RCD disconnects the circuit they are on. However, I keep an eye on several houses with fridges and freezers on RCD protected circuits and this has yet to be a problem in any of them. The sort of telecom/data handling equipment one has in houses doesn't particularly benefit either, if it did then people would be advocating dedicated supplies for televisions and the like. I have no idea what you mean by "any RCD protected circuit".

So, is you objection actually an objection to individual fuses for equipment, rather then the final circuit wiring?

Provided the system is designed, installed and maintained properly such a fault will be very rare. ISTM that there is no reason to design electrical systems on the assumption that the design, installation or maintenance will be poor, especially when the UK approach has been shown to be safer.

Who is this "we" and what size of panel have they been used to?

Excellent, personal abuse. I disagree with you and so you accuse me of having a closed mind.

Ah, so you do now accept that there is at least one more advantage to ring wiring other than just cost.

[Jerry]

supplies,

So you admit now that ring circuits can (and do) casue problems by the nature of their disgn?

However, I keep an eye on several houses with fridges

The point I'm making is that one fault tripping the distr' panel protection can and will take out every appliance on a ring circuit [1], with radial that can't happen. Also one has to think about maintenance etc., with the ring circuit isolated many houses now only have on useable socket, that on the cooker supply (if of fitted).

[1] one then has to find out what appliance, accessory or section of wiring has caused the fault before any appliance can be re-supplied.

There are some outlets that benefit from additional protection (RCD, Surge protection etc.), with radial circuits that protection can be placed within the distr' panel, rather than an unsightly socket or (worse) a plug-in device that's use might get forgotten or ignored.

So you think that a 2 amp appliance protected with a 30 amp device is safer than if that protection was 15 amps or less when some halfwit overrides the plugs internal protection device?

Perhaps you can't or are not old enough to remember when houses were wired with radial circuits?

If you want to take the remark as personal abuse so be, it was not intended to be, I was just pointing out that some will defend what they have been told without question - that is not a fault of the individual but of the (wider) 'education system'. People are not (and have not for many years) being taught to question any more, but to just accept what we are told.

Cheapness is not always an advantage...

[Andrew Gabriel]

When I do a rewire, I put in an non-RCD protected circuit. This gets things like fridge, freezer, washing machine, oven (if 13A plug type), central heating, burglar alarm (if not on lighting circuit), any life support systems such as fish tank filters and heaters (with a dedicated RCD), etc, i.e. all the things you don't want to trip off because of some appliance's earth leak, and which don't represent any significant safety risk due to their own earth leakage (except fish tank, hence dedicated RCD).

[Andy Wade]

Radial circuits can cause problems by the nature of their design too. In both cases the designer would have to have failed to consider the use to which the circuit is to be put.

Uh? - a trip on a radial circuit will also take out every appliance on that circuit.

Most houses tend to have two rings, typically for ground floor and first floor, and a third ring for the kitchen is now becoming common practice. Only very small properties or ones wired a very long time ago will be found with one ring circuit.

The same is true with any circuit. Your points really are all about the number of outlets / appliances / floor area served by the circuits, rather than the actual circuit topology.

The same is true with ring circuits, indeed normal practice is now for all house ring circuits to be RCD protected at the distribution board.

This is an irrelevant point since a 13 A plug fuse perfectly well protects a 0.5 mm^2 flex (for normal flex lengths), this being the smallest flex in common use. The halfwit would need to fit a solid quarter-inch bar in place of the fuse to cause any real danger!

I am, and your point is ...?

Radial socket circuits are still permitted of course and are often used, although I've often noticed that electricians will unthinkingly install

32 A ring where a 20 A radial might have been more sensible.

Nevertheless the ring concept is economical and convenient and has certainly stood the test of time.

Another advantage of the ring is the relative ease of implementing the Section 607 high-integrity earthing requirements, where needed.

[Jerry]

supplies,

But what then happens if one of those appliances takes the supply out, such as washing machine or cooker say, if the owner is not at home (quite likely in the case of a WM fault) one has a tank full of dead fish on there return later than day? Also what if the owner wants to move the fish tank, all a radial circuit requires is the RCD moved within the distr' panel, not a re-wire as in the case of a ring circuit...

[Andrew Gabriel]

These items are all separately protected by their 13A fuses. It would require a failure of the wiring installation to take them all out, which is a very rare occurance. Actually power cuts are a much more likely cause to lose that whole circuit, even in locations where they are rare.

[Jerry]

circuit

Yes, but not the whole house, most would not be running more than two or three appliances of any one radial in practice, it would also be far more simple to re supply any non faulty appliances from other radial circuits.

ignored.

board.

Hahahaahahahahhahahahahaha

Yes, one device trips the RCD and the rest get switched off at source!

device is

halfwit

Read what I said, 30 amps, not 13, there is no device in the plug after a halfwit wraps a bit of 2.5mm wire (or what ever) around the fuse retainers. If you have never seen such abuse you must have a sheltered life!

So it really come down to cost and ease for the contractor / builder (were renovation / new construction is concerned anyway), not what will make life easier for the owner later. I suspect that as 'home automation' becomes more popular in renovated and new build the radial circuit will become common again as each circuit is more adaptable.

[Guy King]

The message from Andy Wade contains these words:

Like mine - which recently sprouted a new ring for the conservatory 'cos I didn't want to add to an already busy ring. I could easily have done with with a radial considering how little power is likely to be used in there, but since the parents in law's skip was full of 2.5mm T&E I couldn't think of a good reason not to.

[Jerry]

,

Hmm, so MCB's are slower acting that re wireables?

[David Hansen]

On Sun, 27 Aug 2006 13:15:25 +0100 someone who may be "Jerry" wrote this:-

All of a sudden re-wirable fuses have been introduced to the discussion. Fascinating.

[David Hansen]

On Sun, 27 Aug 2006 11:47:48 +0100 someone who may be "Jerry" wrote this:-

I don't recall claiming that ring final circuits are perfect. Feel free to point to a posting where I did. If you can't others can draw their own conclusions.

All designs of circuit have advantages and disadvantages. Perfection has yet to be achieved in any of them. However, in many circumstances the ring final circuit is the best compromise.

That point is obviously incorrect. A fault on a radial circuit which causes the protective device at the consumer unit to open will, one hopes, disconnect every appliance on that circuit. One could argue that there may be fewer appliances on the radial circuit, but that is not the point you made.

I have looked after a few such houses over the decades. However, I have never yet been stopped from using power tools for works on the system as a result.

Such a device will still disconnect every appliance on the circuit, one hopes, when it opens.

I note that you have failed to answer the question.

Houses still are.

When radial circuits were used exclusively for general power circuits there might typically be a 15A outlet in the living room and a 5A outlet in each bedroom. That is very different from conditions today.

I tend to agree. However, accepting what I am told without thinking about it is not something I do.

[Jerry]

draw

Well seeing that you were making similar remark towards myself I thought I would reply like wise, please feel free were I said that radial circuits are perfect - all I have done is point out that there is less chance of user abuse and when that abuse happens it is less dangerous than when a ring circuit is in use.

Perfection

We will have to disagree on that.

which

As you said, it depends on what is connected, my point is that critical applications (such as freezer or fish tank for example) can easily be connected to their own supply in effect by the home owner - that is not possible with a ring circuit.

Perhaps you are lucky...

(RCD,

ignored.

Only those selected to be on that circuit, I hope no one would supply anything that was critical on such a protected circuit unless it expressly required such protection and certainly not with other (unrelated) appliances.

halfwit

I have answered the question.

Your point is what exactly?

[Jerry]

If you read the context, which you have (conveniently?) snipped, you will see that the reply was in relation to remark about fuses fitted within the BS1363 plug. Perhaps I should have just said 'fuse wire'...

[David Hansen]

On Sun, 27 Aug 2006 17:30:55 +0100 someone who may be "Jerry" wrote this:-

You may have made such an assertion. However, you have not made a convincing argument to back up that assertion. If you would like to do so then please do.

You have not yet made a convincing argument to back up that assertion.

Another incorrect assertion. Generally it will only be possible to connect such equipment to separate circuits if each socket outlet is connected to the consumer unit by its own radial circuit. That would mean dozens of radial circuits in my house. If the usual approach in radial wiring is adopted instead then in most rooms every socket will be on the same circuit.

I doubt it.

Fairly obvious. One 15A and three 5A fuses for general power circuits is very different from say 37 protective devices to feed outlets individually, or even 11 protective devices to feed a small number of outlets on each radial circuit. One of the far-sighted options for adopting ring final circuits was to allow for a far larger number of socket outlets than before, without the problems of wiring them radially.

[David Hansen]

On Sun, 27 Aug 2006 17:36:13 +0100 someone who may be "Jerry" wrote this:-

It is available should anyone want to read it and smile. Your point about the operating speed was in response to the following:-

"These items are all separately protected by their 13A fuses. It would require a failure of the wiring installation to take them all out, which is a very rare occurance. Actually power cuts are a much more likely cause to lose that whole circuit, even in locations where they are rare."

Your point has nothing to do with power cuts and neither does it have anything to do with 13A fuses.

Fuses inside such plugs are not rewirable.

[Jerry]

I have indicated how easy it would be for some halfwit to bridge out the fuse in a BS1363 plug, now tell me how easy it would be to swap / bridge a CB in a distr' panel...

I have, you are just in denial I suspect.

owner -

would

Against all sockets in the house / floor being on one protection device when a ring is used...

Perhaps you just work in mansions or houses of multiple occupancy...

room

Except that all outlets on the ring, sometimes meaning all power in the house except the cooker in older properties, fail due to a fault, not forgetting that a 2 amp appliance can easily become grossly under protected.

Ring circuits were brought in to save on expencive wire, remember when alloy wire as tried in an attempt to keep cost down, and to a leaser extent save on labour costs. At the time, ring circuits made sense because the there were fewer appliances in the house than now - it would be quite easy to over load a single ring circuit now days - hence why, even in medium sized houses, we now find two or more ring circuits having to be installed.

[Jerry]

fitted

Nor does trolling, a sure sign that you are loosing the argument and know it, my point was the speed of tripping between relative protection devices, are you implying that an MCB is slower than a cartridge fuse?

[zymurgy]

> > There is also a dimmer switch that is not connected to anything, so

Unless she lives in Italy ;)

[Owain]

To *isolate* any circuit for maintenance requires removal of the CU cover and physical disconnection of the neutral, as MCBs only switch the live, and few houses have RCBOs.

While isolating the circuit it is fairly trivial to put a temporary alternative supply in.

Owain

[Owain]

No, ring circuits made sense then for the same reason they do now - anticipation of a large number of low powered portable appliances.

About the only difference now is the presence of cold fill washing machines and dishwashers, and as they aren't portable appliances they could easily be provided with their own radials - although it's usually easier to install a second ring and gain the benefits of capacity for more sockets.

Owain