PIV electrics

[EFLImpudence]

With respect, you're either being silly or not reading what I write. Of course I would not be able to use 'low-rated' plug fuses if they didn't exist (either because they weren't manufactured or because I lived somewhere that did not use plug fuses at all). As I said, I do live in a country which uses plug fuses, but I would not use anything other than 13A ones if I did not think that there was a potential benefit to be had by using lower-rated ones.

Ok. You are pretending not to understand.
If you lived in a country where plug fuses are not used - AND you had not had it drummed into you that the smallest one should be used - would you consider it necessary to engineer your own?

Everything, I would have said. You said that the issue of plug fuses only arose because of ring finals. In response, I suggested that unfused plugs on a 32A radial probably would not be regarded as acceptable.

Yes, you did, and with respect it was a silly thing to say.
That would not be the alternative.

If neither of us can think of a positive downside, but I (but not you) think that there is conceivably a positive upside, can you not understand why I feel that one might as well do it (given that it essentially comes with no cost).

I can understand but am trying to elicit a positive example of this conceivable upside. Surely you can work out a scenario.

It may well have been considered 'impractical' in countries which do not have fused plugs, since it would presumably require the installation of multiple 3A circuits,

I don't follow why that would be necessary.

and probably the invention of some new plug/socket to prevent things being plugged into the wrong socket.

What has the 'wrong' socket got to do with it?
Would it not have been within their wit to just make a plug into which a fuse could be fitted - like they did in Britain?

I have repeatedly explained what 'potential positive upside' that I see.

Have you?

In the absence of downsides, a 'potential upside' (even if only slight) swings the balance in favour of that approach. It may conceivable occasionally do good, and the 'worst' that can happen is that it provides no benefit.

Example, please.

Think of a person with a serious illness who is offered a choice of two treatments. There is no known downside of either, but one of them might conceivably (but very probably not) offer a slightly greater chance of saving their life. Which would they choose?

Shouldn't the analogious choice be between two which will save their life?

 

[stillp]

Why would anyone decide to specifically do that?
It was to double the capacity of an existing radial by using a shorter (than the existing circuit) length of cable back to the CU.
Thus saving copper as well.


That doesn't make sense.

I can only repeat what was told to me by a member of the original working group. At the time it seemed to be believed that earthing was the most important aspect of an electrical installation, so the installation would be safer if there was redundancy in the cpc. (Remember the brief was to design the safest form of domestic installation.) Using a ring circuit and T & E cable to provide redundancy of the cpc results in the live conductors being more-or-less in parallel, so the CSA can be reduced, but that was not written into the specification until after the ring final had been decided on.
Now you might disagree with their rationale, but that is what I was told by a well respected senior engineer (and specialist in fuse protection) who was there at the time.

 

[winston1]

I don't know what he understands, (I suspect very little).

Well you suspect wrongly, as usual.

 

[stillp]

Never mind what you are told.

You might choose to ignore statements of fact from well-respected engineers, but I will not.

Cite the evidence which justifies your assertion that overseas societies are satisfied with a lower level of protection than is accepted in the UK wrt circuit OPD protection of appliances.

Search Eurostat for the comparative statistics for fires of electrical origin across the EU. That justifies the assertion that the UK installation system is safer than others. The UK system includes protection of appliances by plug fuses. Other countries do not use plug fuses.

Cite the evidence which justifies your assertion that circuit OPDs are indeed meant to protect appliances.

Kindly tell me where I have 'asserted' that. While you're at it, cite some evidence that the laws of physics no longer apply, since that is what you seem to be suggesting. Whatever they are 'meant' for, plug fuses will provide protection for appliances that are connected via those plugs. It is simple physics that a smaller value fuse (otherwise of the same characteristics) will allow less let-through energy than a larger one and will therefore provide closer protection to anything downstream of it.

Totally unacceptable.

Find them, and publish them, or reference the original sources, or stop relying on them.

You might find that totally unacceptable, as I find the implication of your demand totally unacceptable.

 

[stillp]

So not within appliances then.

That is correct. It does not disprove my statements though. I'm quite sure some will have been blamed on appliances and their connecting cords.

 

[winston1]

The UK system includes protection of appliances by plug fuses. Other countries do not use plug fuses.

No it doesn't. It includes protection of flexes by plug fuses. That is what the fuse is for.

 

[stillp]

No it doesn't. It includes protection of flexes by plug fuses. That is what the fuse is for.

Are you denying that the provision of a fuse protects the appliance as well as its flex? (Leaving aside the fact that the flex is part of the appliance.)

 

[ban-all-sheds]

I can only repeat what was told to me by a member of the original working group. At the time it seemed to be believed that earthing was the most important aspect of an electrical installation, so the installation would be safer if there was redundancy in the cpc. (Remember the brief was to design the safest form of domestic installation.) Using a ring circuit and T & E cable to provide redundancy of the cpc results in the live conductors being more-or-less in parallel, so the CSA can be reduced, but that was not written into the specification until after the ring final had been decided on.
Now you might disagree with their rationale, but that is what I was told by a well respected senior engineer (and specialist in fuse protection) who was there at the time.

I haven't read the history paper here http://www.theiet.org/resources/wiring-regulations/ringcir.cfm?type=zip all the way through, but it does not contain the strings 'redunda' or 'fail'.

 

[stillp]

I haven't read the history paper here http://www.theiet.org/resources/wiring-regulations/ringcir.cfm?type=zip all the way through, but it does not contain the strings 'redunda' or 'fail'.

And your conclusion from that is what?

 

[winston1]

Are you denying that the provision of a fuse protects the appliance as well as its flex? (Leaving aside the fact that the flex is part of the appliance.)

Probably, because the appliance should have its own internal protection.

 

[stillp]

Probably what?

 

[JohnW2]

Ok. You are pretending not to understand. If you lived in a country where plug fuses are not used - AND you had not had it drummed into you that the smallest one should be used - would you consider it necessary to engineer your own?

I am truly not 'pretending' anything. The answer to that question is obviously no.

Yes, you did, and with respect it was a silly thing to say. That would not be the alternative.

Well, it's certainly 'an alternative' now. I don't know when 30A radial socket circuits came into being, but it might well have been at the same time as fused plugs were introduced (i.e. at the same time as ring finals).

I can understand but am trying to elicit a positive example of this conceivable upside. Surely you can work out a scenario.

I did, pages ago. IF the load does not contain fuse(s) that will blow before any external fuse/MCB operates, then, in the event of a 'fault' (everyday sense) of non-negligible impedance (i.e. 'an overload') arising in the load, the amount of energy dissipated in the load (hence amount of potential damage done) will be determined by the let-through energy of whatever (external) device operates first. Hence, the lower the rating of the plug fuse, the less energy dissipated and hence potentially less damage done. You, BAS and others may argue that loads without internal protection should not exist - but they do.

I don't follow why that would be necessary. .... What has the 'wrong' socket got to do with it? ... Would it not have been within their wit to just make a plug into which a fuse could be fitted - like they did in Britain?

Oh, yes. I didn't realise that you were talking about other countries moving, at least partially, to a UK-like system with fused plugs. Yes, if they had felt the need, they could have done that.

Have you? .... Example, please.

Please see my reply to your essentially identical question above.

Shouldn't the analogious choice be between two which will save their life?

That was, with qualification, the implication of what I wrote ... both treatments have similar probabilities ('chances' in your language) (above 0% but below 100%) of saving their life, but with Treatment A conceivably (but probably not) have a slightly higher probability of saving their life than Treatment B. If neither have known 'downsides', I suspect that few people would fail to 'grasp the straw' which might be offered by Treatment A.

Kind Regards, John

 

[JohnW2]

.... Whatever they are 'meant' for, plug fuses will provide protection for appliances that are connected via those plugs. It is simple physics that a smaller value fuse (otherwise of the same characteristics) will allow less let-through energy than a larger one and will therefore provide closer protection to anything downstream of it.

Exactly.

I suspect that one of the problems some people are having is in not thinking about what both of us have written - that regardless of what the fuse is 'meant' to do, physics dictates that (unless internal fusing operates first), a lower rating fuse will also result in less dissipated energy and hence potentially less damage.

However, as we've seen, they might also argue that loads without adequate internal protection (which would operate before any external device) should not exist - but since they very much do exist, I am not very moved by that argument.

Kind Regards, John

 

[ban-all-sheds]

You might choose to ignore statements of fact from well-respected engineers, but I will not.

Without any facts to cite they cannot be statements of fact.

Search Eurostat for the comparative statistics for fires of electrical origin across the EU. That justifies the assertion that the UK installation system is safer than others. The UK system includes protection of appliances by plug fuses. Other countries do not use plug fuses.

If you are asking me to do the search that means that you do not have any evidence you can cite which shows that there are significantly more fires in electrical appliances in countries with similar electrical installation qualities to ours but without fused plugs.

Kindly tell me where I have 'asserted' that.

Here:

Following that, why was it considered necessary to fit other rated fuses in the plug - or did it just happen because there were such things - as John does?

To provide closer protection to the appliances that are connected to that installation.

While you're at it, cite some evidence that the laws of physics no longer apply, since that is what you seem to be suggesting.

I'm not suggesting that.

Whatever they are 'meant' for, plug fuses will provide protection for appliances that are connected via those plugs. It is simple physics that a smaller value fuse (otherwise of the same characteristics) will allow less let-through energy than a larger one and will therefore provide closer protection to anything downstream of it.

Indeed.

But the argument is about whether that is their purpose, and if it is, why are they not needed in other countries?

You might find that totally unacceptable, as I find the implication of your demand totally unacceptable.

OK, fine.

Now we all know that you think it is acceptable to make assertions for which you claim a factual basis when in reality you do not have any such evidence, or if you do have it you think that we should all just bow down and accept what you say because you cannot be **sed to produce the evidence.

 

[ban-all-sheds]

And your conclusion from that is what?

That there is nothing in a 23-page history of the 13A plug and the ring circuit written by a Fellow of the IEE which references any discussion of redundancy or failures.