Warning: I got sloppy.

[IsleOfWighter]

People, people, people.

"Turning it off at the plug" is what's known as an idiomatic expression.

As for the "plug socket"... Well, next to where I was working was a socket wrench, a USB socket, a light bulb socket and a model of a human skull with two eye sockets. I was merely pointing out which of those I was talking about.

 

[ericmark]

For those wondering these

are plug/sockets common in France but not in the UK, as to which is the plug and which is the socket I can't say, I would call the wall mounted unit a socket, but if you get down to earth then it is a plug!

As to accident yes nasty, it does pose the question are switches on sockets good or bad? With no switch it would not have happened. The sound and some times flash of removing a plug when under load is stopped when a switch is fitted, and also the chance of touching a live pin, however with modern plugs with plastic insulators on the pins it is no longer really required.

I think it highlights the difference between switching off and isolating. Not so much with sockets, but with lights so many switches today don't isolate, there must be some current flowing to work the electronics, other wise the remote control would not switch it on.

It is so easy to fit sockets with the line and neutral reversed, I remember having boxes of sockets and one box the line and neutral were reversed, so easy on a second fix not to read the writing on every socket, if you have fitted 20 sockets in a row with line on left if the 21st socket has line on right it is so easy to miss. The same applies when renewing a socket, one does not naturally expect the line and neutral to reverse between old and new.

I have been reasonably lucky, after a nasty shock due to shared neutral, I have used a neon screwdriver a lot for terminals, OK today I have a clamp on ammeter, but not always enough room to clip it on, so I am a great believer in the neon screwdriver. Not as primary testing device, but as second string to ones bow.

I got a belt in my father-in-laws house, I am so use to houses with RCD's fitted, his lamp has been knocked off a silly hook and was dangling by the cables, I drew the fuse and refitted, put fuse back in, then noticed the metal bell covering wires has dropped a bit, so went to push it back up, there must have been a strand which touched inside of bell cover, the strand was soon melted and auto removed, but not before I got a belt.

In my late mothers house I also have a large lamp hanging from ceiling which also needs a hook, however I fitted this one, and the whole hook part of ceiling rose slides out, so not balancing on a ladder trying to wire it up. I wire on the floor then simply slide in the plug.

I like the idea however these

are expensive at just over £20 I can see why the cheap versions are used. These

are just over £4 and rated at 5 kg I do wonder however with most ceiling roses rated at 5 kg if during the EICR we were to test ceiling roses could hold 5 kg how many would be pulled out of plaster board? To my mind should be screwed into a beam, however seen many only into plaster board. The metal one with hook still only rated 5 kg by the way.

I think RCD protection has made us sloppy, we do not isolate as we should, many times with a TT house I have only switched off the MCB, I know I should use a double pole isolator not the MCB but I still take a chance. Before the RCD many caravans had a warning light and a push button to reverse to polarity, since the RCD these consumer units seem to have vanished, although I note in my caravan the MCB's are double pole.

 

[JohnW2]

Fair enough, we will have to agree to disagree! I agree they are all important, but I think that correct polarity is on a higher level than dead testing as it's a one off thing to get right.

Given that we're both sensible people, I don't think we are really disagreeing, other than perhaps over the question of whether it really makes any sense to attempt to put the three (all important) things in 'order or importance'.

It is true that getting the polarity right is a one-off thing. However, the person who doesn't ever 'test for dead' when they do electrical work will be at risk every time they do any such work, and in the great majority majority of cases that will be despite polarity being correct. In other words, a person who spends a lifetime doing electrical work will be 'at potential risk' far more times if they never 'test for dead' than if one or more of their sockets have reversed polarity (and will never be 'at risk' even if there is some reversed polarity if they always 'test for dead') - so I really don't think it makes much sense to try to put these measures in 'order of importance'.

Without having a poll, or asking for 'confessions', I imagine that the majority of us have, on occasions, done some foolish 'cutting of corners'. However, in the case we are discussing, I think the silliest thing of all (which I doubt many of us would ever do) was to work on a piece of plugged-in equipment whilst it was still plugged in!

Same as the selection of 240v rather than 1kv as the mains voltage. That one decision has an even bigger impact on safety than anything else.

I'm not sure that is all that good an analogy, particularly given that it is to an appreciable extent 'arbitrary' - and those across the Atlantic might well suggest that we (and most of the rest of the world) made the wrong decision!

Kind Regards, John

 

[ban-all-sheds]

Same as the selection of 240v rather than 1kv as the mains voltage. That one decision has an even bigger impact on safety than anything else.

How many people are able to make a selection between using 240V and 1kV, and thereby risk getting it dangerously wrong?

I'm not aware of a way in which I could select anything other than 230V, even if I wanted to, nor have I ever heard of anyone who can.

And I've never seen anybody here asked a question along the lines of "You have selected 230V, and not 1kV, haven't you?".

 

[JohnW2]

If it's a new house, the electrical installation should have been tested when it was built - one of those tests is to confirm polarity and that switching is on the line conductor.

Whilst, as this case illustrates, it probably should be the case, I'm far from convinced that even the initial testing of a new installation would involve checking of the polarity at every socket. That certainly had not been the case with PIRs/EICRs I have seen done on existing installations.

Kind Regards, John

 

[Taylortwocities]

I'm far from convinced that even the initial testing of a new installation would involve checking of the polarity at every socket.

That's what we are taught at college, but we all know that this often doesn't happen on site.

 

[JohnW2]

That's what we are taught at college, but we all know that this often doesn't happen on site.

As I said, that's what I would have expected - and this thread illustrates why. However, what were you taught about EICRs (or whatever they were then called), because it seems that testing of every socket is far from a universal (or necessarily even common) practice in that context.

Kind Regards, John

 

[John D v2.0]

Same as the selection of 240v rather than 1kv as the mains voltage. That one decision has an even bigger impact on safety than anything else.

'm not sure that is all that good an analogy, particularly given that it is to an appreciable extent 'arbitrary' - and those across the Atlantic might well suggest that we (and most of the rest of the world) made the wrong decision!

I realise the specific voltage is arbitrary but I doubt Americans would suggest using 1kv either, since their neutral to phase voltage is even lower than ours.

Safety is similar to security, as well as testing and quality control.
You need to take a layered approaching where everything is scored for severity and cost, then take the best combination of those from all layers.
So on a building site a higher layer would be provide scaffolding, a lower layer would be make sure all workers are trained to use a ladder right
Both are important, but the scaffolding makes everyone safe with no further effort, the ladder training works on individual cases and needs applying every time.

 

[JohnW2]

I realise the specific voltage is arbitrary but I doubt Americans would suggest using 1kv either, since their neutral to phase voltage is even lower than ours.

That was my point - that they may well suggest that almost everyone other than themselves have decided upon a phase-to-neutral voltage which is 'dangerously high'.

You need to take a layered approaching where everything is scored for severity and cost, then take the best combination of those from all layers.

Indeed - although in some situations, the minimum acceptable level of safety will involve a combination of essential measures/practices, such that it is inappropriate to distinguish between the 'levels' of practices all of which are essential.

So on a building site a higher layer would be provide scaffolding, a lower layer would be make sure all workers are trained to use a ladder right. Both are important, but the scaffolding makes everyone safe with no further effort, the ladder training works on individual cases and needs applying every time.

Again, I'm not sure that that is a very good analogy. Apart from anything else, the workers would normally have to be trained in how to safely use ladders to get onto the scaffolding.

Given that we agreed that all the measures we are discussing are important, I'm really not sure what point you are trying to make. You are presumably not suggesting that if one is sure that polarity is correct, that 'testing for dead' becomes 'less important' - let's face it, even if one were relying on SP switching in a socket to produce 'safe isolation' (which is iffy at the best of times), such switches have been known to fail 'closed', even if wired with correct polarity.

Kind Regards, John

 

[JBR]

Working on something that could be live is clearly not very sensible.

Just the other day I decided to replace a bathroom fan which is both very noisy an pitifully ineffective! Upon removing the front cover, I read the cryptic message "supplied from more than one source". Eh? Which sources?

Turning off the power at the adjacent light switch turned off the bathroom lights AND the fan, but upon checking (with one of those pen things that everybody on here dislikes!) there was still power at the interior connections in the fan. I still haven't fathomed that out; if there is power (at live, switched live and neutral), isn't the fan working?

Anyway, I went back to the CU and turned off the circuit breaker for all sockets in that part of the house (the bathroom lights and fan are fused down from the sockets circuit) and checked that there was now no power in the fan. I could then safely do the change.

It just confirms though that one should check beyond any doubt that there is no power where you are working. Yes, perhaps I should really have turned off the power to the whole house completely at the CU, but I was confident that it was safe.

 

[seasickstevie]

Mk sockets have double pole switches.

I think pretty much all 'reputable' makes of socket have DP switches these days (and have done for some time).

 

[ericmark]

That's what we are taught at college, but we all know that this often doesn't happen on site.

I remember my C&G2391 exam, I had a board with a selection of units which was designed to emulate a house, however I did not even need to make one step to do the testing and the ring final was just three sockets, however it took an hour to test. If I took the same care with a house looking at 2 days to test, clearly one can't take the care and time taught in collage with real life.

However in real life only one job, Rock Savage chemical plant ever insisted on full testing for dead, in fact if you did not have the test gear with you your site pass would be withdrawn which in real terms means you got the sack. However with all that the proving unit produced 500 volt only, so although all the neons lit at 500 volt, you had no idea if any would light at 230 volt. Unless the proving unit starts at 50 volt AC or less, it may as well be thrown in the bin. Today I see proving units do ramp up, I had a 12/230 volt inverter which doubled as a proving unit when required, but in real terms it was just making a show of testing the tester, always used a tester which had no switch or battery when testing for dead, so in real terms it was highly unlikely to fail. And unless you short out the conductors to earth, there is nothing to stop them becoming live again. I have had that, not domestic, but tested for dead, cut cable, then found sparks coming from cable as the PLC had activated a contactor and made the cable live.

After that I refused to remove redundant cables while the plant was running. It was a near miss.

 

[flameport]

Turning off the power at the adjacent light switch turned off the bathroom lights AND the fan, but upon checking (with one of those pen things that everybody on here dislikes!) there was still power at the interior connections in the fan. I still haven't fathomed that out; if there is power (at live, switched live and neutral), isn't the fan working?

Possible that the switch only disconnected the neutral, either by incompetent installation or because of some internal failure if it was a double pole switch.

 

[JBR]

Possible that the switch only disconnected the neutral, either by incompetent installation or because of some internal failure if it was a double pole switch.

Nothing so simple, I'm afraid. I removed the 3A fuse and the connections in the fan were still live!

 

[JohnW2]

Nothing so simple, I'm afraid. I removed the 3A fuse and the connections in the fan were still live!

I wonder 'how live' they really were? You previously wrote:

... upon checking (with one of those pen things that everybody on here dislikes!) there was still power at the interior connections in the fan.

Those 'pen things that everyone on here dislikes' are quite capable of 'detecting voltage' even when there is no conductive connection to a source of electricity.

Kind Regards, John