Is My Masterplug RCD Safe? Please Help!

[JohnW2]

This is a difficult subject because we all use words which used to mean something else, if not even the opposite of their meaning now, because of this 'evolution'. I disagree with it being called evolution and think corruption is more accurate.

I think that's probably a bit harsh. Even most academic linguists (with the possible exception of French ones ) acknowledge and welcome the evolution of language and, indeed, even the 'variety of language' that can exist at one point in time.

However, as in the recent changing of the meaning of 'literally', this is wholly because of it's misuse by the ignorant and so the OED is acknowledging this misuse without mentioning the reason.

I don't know if this is another of your unintentional bits of irony, but the word 'ignorant' was widely used by my parent's generation to have a meaning which was then incorrect, although the dictionaries of today have now assimilated that previously incorrect meaning!

If youngsters use words 'wrongly' between themselves as a code so that others do not know what they are talking about this is bound to cause misunderstanding in the future. What does 'wicked' now mean?

I think this is very different. Certainly for all of my memory (around 60 years), and probably for a lot longer, each generation of youngsters has developed its own 'abuses of language', usually much detested by older generations. However, in most cases these have been transient fads/phases/whatever and have not persisted into common usage by later generations. It may partially be 'code', but is probably more a case of 'juvenile rebellion' or attempts to assert themselves as a group! Some of the (ab)uses of language which were heard every day in my school playgrounds would be meaningless to current0day youngsters, and those of 50 years time may well not know anything about a strange use of the word 'wicked'! Having said that, I'm not sure that what is currently being done to 'wicked' is necessarily any worse than what we and others have already done (presumably 'permanently') to words like terrible/terribly, horrible/horribly, awful/awfully, wonderful/wonderfully etc. etc.

... and no-one has taken my bait about 'continuity test' yet (and I might possible also have mentioned 'terminate'!)

Kind Regards, John

 

[JohnW2]

Edited to remove wrongly used apostrophe placed to see if anyone noticed.

Too slow - already quoted, noticed and highlighted in red

Kind Regards, John

 

[echoes]

It's well known that humans are generally hopeless at estimating risk. Instinct is often proven to fail. As an example:

Suppose in a population, there is a 1 in 10,000 risk of developing a disease which is always fatal.
There is a test which is known to be 99% accurate in diagnosing the disease.

A person takes the test. The result is positive. Should that person be worried?






























Since for every 10,000 people, the test can be expected to incorrectly diagnose 100 people, the chances of actually having the disease, WITH a POSITIVE test result is only 1 in 100.

Just goes to show...

 

[ban-all-sheds]

no-one has taken my bait about 'continuity test' yet

Go on then - what did that used to mean?

 

[ban-all-sheds]

A person takes the test. The result is positive. Should that person be worried?

Why not?

They might be exhibiting symptoms consistent with having the disease.

Or they might, IMO quite naturally and reasonably, be worried to learn that there was a 1 in 100 chance that they had a fatal disease.

I assume that by "a test which is known to be 99% accurate" you mean that 1% of the positive results are false?

 

[JohnW2]

It's well known that humans are generally hopeless at estimating risk. Instinct is often proven to fail.

You don't need to tell me that - I spend a fair bit of my time trying to get people to understand probabilistic information, often with great difficulty ... and it's exactly the point I've been making.

As an example: Suppose in a population, there is a 1 in 10,000 risk of developing a disease which is always fatal.
There is a test which is known to be 99% accurate in diagnosing the disease. ... A person takes the test. The result is positive. Should that person be worried? ... Since for every 10,000 people, the test can be expected to incorrectly diagnose 100 people, the chances of actually having the disease, WITH a POSITIVE test result is only 1 in 100.

I'm with BAS on this one. Like him, in view of the figures you quote, I'm assuming that your '99% accurate' means that the false positive rate is 1%. As he's said, a 1 in 100 chance of developing an inevitably fatal disease really is plenty high enough to worry many people. How much they should worry obviously depends upon the details. If it's a disease which will not develop for decades, then people would worry much less - but if you told a 20-year old that (s)he had a 1 in 100 chance of developing an inevitably fatal disease within the next five years, I suspect that they might be very worried!

Anyway, you seem to feel that a 1 in 100 risk is pretty low, so what do you think about RCDs as a measure to reduce the risk of domestic deaths by electrocution? If, per my recent posts, one says that the current risk of such a death is about 1 in 3 million (somewhat less than 1 in 100 ), do you think there is any sense in us having RCDs at all (to 'save lives')? Even if the 1 in 3 million figure was desparately wrong (say 100 times too small), the risk would still be dramatically lower than the 1 in 100 which you think is small, and imply that one need not worry about!

Kind Regards, John

 

[JohnW2]

no-one has taken my bait about 'continuity test' yet

Go on then - what did that used to mean?

It's not only 'used to' - it still has its correct meaning!

An electrical continuity test is (in keeping with the definition of 'continuity') an essentially qualitative test (well, one with a dichotomised result), with a yes/no answer, dependent upon whether resistance is above or below some arbitrary (low) threshold. The 'bleep' function on a multimeter represents a continuity test.

On the other hand, measuring resistance is measuring resistance (a quantitative exercise) even if the resistance is low, but electricians seem to refer to the quantitative measurement of resistance as measuring/testing 'continuity'.

Kind Regards, John

 

[EFLImpudence]

Edited to remove wrongly used apostrophe placed to see if anyone noticed.

Too slow - already quoted, noticed and highlighted in red

D'oh - I missed that.

 

[ban-all-sheds]

You don't need to tell me that - I spend a fair bit of my time trying to get people to understand probabilistic information, often with great difficulty

Try them on the Monty Hall problem...

 

[JohnW2]

You don't need to tell me that - I spend a fair bit of my time trying to get people to understand probabilistic information, often with great difficulty

Try them on the Monty Hall problem...

I don't think this is the place for that - it's rather different from getting the man in the street to understand simple probabilistic issues, since it gets even very clever statsiticians tied up in complete knots and arguing very heatedly The answer to the problem has to be just about the most counter-intuitive truth I've ever come across in my life!

The Monty Hall problem holds a record in my experience for the length of an on-line discussion thread - I can't remember the exact number of messages, but it was very much into 'four figures' - and, even at the end, there were some very senior and respected/eminant statisticians still refusing to accept the correct answer!

Kind Regards, John

 

[EFLImpudence]

However, as in the recent changing of the meaning of 'literally', this is wholly because of it's misuse by the ignorant and so the OED is acknowledging this misuse without mentioning the reason.

I don't know if this is another of your unintentional bits of irony, but the word 'ignorant' was widely used by my parent's generation to have a meaning which was then incorrect, although the dictionaries of today have now assimilated that previously incorrect meaning!

I'm not sure which you mean.
I meant 'the unknowing'.

Do you mean your parents used it to mean disrespectful?

 

[ebee]

Ban,
that Monty Hall Problem got me.
(I did not see the explanation of the answer, just the what the producers said after it had run a while and the results were found to be similar to their calculations).

I eventually gave up to it because I was thinking a 1 in 3 chance becomes a 1 in two chance (a 50% increase on a winning outcome) .

Two weeks later, having not thought about it, I looked in the mirror, and Eureka - the answer came in a blinding flash out of the blue- simples once you twig it.

Strange world innit? LOL

 

[JohnW2]

I don't know if this is another of your unintentional bits of irony, but the word 'ignorant' was widely used by my parent's generation to have a meaning which was then incorrect, although the dictionaries of today have now assimilated that previously incorrect meaning!

I'm not sure which you mean.I meant 'the unknowing'.

Yes, I realised that - the original correct meaning, still the 'official meaning'

Do you mean your parents used it to mean disrespectful?

More-or-less. Now (but not in my parents' day) accepted by the OED as the second (albeit 'informal') meaning - namely "discourteous or rude".

Kind Regards, John

 

[ban-all-sheds]

A meaning not present at all in the Collins 21st Century Edition....

Although it does admit 'fool' for 'ignoramus', after 'an ignorant person'.

 

[JohnW2]

A meaning not present at all in the Collins 21st Century Edition.... Although it does admit 'fool' for 'ignoramus', after 'an ignorant person'.

My parents (and grandparents) certainly did use it to mean something a bit stronger than just 'rude' or 'unacceptable'.

Kind Regards, John