DONT RELY ON RCD's PLEEEEESE.

B

baldsparkies

We seem to have a lot of young sparkies following the trend that RCD's are some kind of wonder device.
To explain,
An elderly lady has just come out of a 3 day stay in hospital.
Why ??
Because a young electrician had installed a dual RCD board to there property and explained how it protected from electric shock, and how wonderful RCD's were.
It left the old couple with a very mis guided conception that they were completely safe regardless.
The old chap had been decorating and left the light switch hanging by the cables.
One evening his wife went to turn the switch off, accidently put her finger behind it, and made direct contact with a live conductor.
Whilst the RCD did operate. She recieved a nasty shock that resulted in hospitalisation.
Now whilst I appreciate the RCD probably helped save her life.
Please dont for one minute think it will protect a user from an electric shock. IT WONT !!
They are a useful aid towards safety in that they can help reduce the possibility of a fatal shock.
But please refrain from telling people they prevent electric shock, and choose your words wisely.
Sorry guys rant over.
 
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that should give the " RCDs are god's gift" brigade something to think about.
 
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baldsparkies said:
We seem to have a lot of young sparkies following the trend that RCD's are some kind of wonder device.
To explain,
An elderly lady has just come out of a 3 day stay in hospital.
Why ??
Because a young electrician had installed a dual RCD board to there property and explained how it protected from electric shock, and how wonderful RCD's were.
It left the old couple with a very mis guided conception that they were completely safe regardless.
The old chap had been decorating and left the light switch hanging by the cables.
One evening his wife went to turn the switch off, accidently put her finger behind it, and made direct contact with a live conductor.
Whilst the RCD did operate. She recieved a nasty shock that resulted in hospitalisation.
Now whilst I appreciate the RCD probably helped save her life.
Please dont for one minute think it will protect a user from an electric shock. IT WONT !!
They are a useful aid towards safety in that they can help reduce the possibility of a fatal shock.
But please refrain from telling people they prevent electric shock, and choose your words wisely.
Sorry guys rant over.
Click to expand...

The above scenario would have happened regardless IMO and its in no way a sparks fault.
 
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Englishman said:
The above scenario would have happened regardless IMO and its in no way a sparks fault.
Click to expand...
I'm sorry to disagree with you English.
But the fact is if you tell people an RCD wil protect them from electric shock, and they trust you as a skilled tradesman.
Then they WILL become complacent, and be lulled into a false sense of security.
Having spoken to the old chap, this is EXACTLY what happened. To quote,
"I thought it was ok to leave the electric on because the RCD would protect us. The young man said it protected from an electric shock"
So yes, the electrician is at least partly to blame for this mis conception.
The supply should have been isolated, I explained this, and after whats happened to his wife he wont make the mistake again.
But what I said in my first post I stand by 100%
 
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One thing that was impressed upon me during my training is that although there is an accepted resistance for the human body, this can vary dramatically from person to person, obviously changing shock risks at different levels. An older person with a weaker heart for example can be more susceptible to fibrilation at lower amperage levels.
Hence the effectiveness of a 30mA RCD depends on the situation.
 
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got too agreed with englishman , its hardly the boys fault , reminds me of the story in america a few years ago , when a salesman sold an old guy a camper van with cruise control and the old guy thought it would drive its self so he switched it on and went for a kip in the back whilst on the motorway , u can guess what happened but hardly the sale mans fault
 
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Old people tend to come from a generation of trust and being able to take people at face value.
Sadly those days are on the decline.
Telling anyone let alone the elderly that an RCD will protect them from an electric shock is plain wrong.
Electricity is dangerous and needs to be treated with respect, end of.
And no amount of wonder devices, over hipe, or BS about what an RCD can or cant do is going to change that.
All I'm saying is an RCD wont protect from shock. And there is no way you or anyone else should be saying anything different.
If you do, then you are giving bad advice, and leading people to believe the RCD can do something that it clearly cannot.
Sorry but to me this is just about common sense, and taking on board your responsibilities as a professional.
 
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baldsparkies said:
We seem to have a lot of young sparkies following the trend that RCD's are some kind of wonder device.
To explain,
An elderly lady has just come out of a 3 day stay in hospital.
Why ??
Because a young electrician had installed a dual RCD board to there property and explained how it protected from electric shock, and how wonderful RCD's were.
It left the old couple with a very mis guided conception that they were completely safe regardless.
The old chap had been decorating and left the light switch hanging by the cables.
One evening his wife went to turn the switch off, accidently put her finger behind it, and made direct contact with a live conductor.
Whilst the RCD did operate. She recieved a nasty shock that resulted in hospitalisation.
Now whilst I appreciate the RCD probably helped save her life.
Please dont for one minute think it will protect a user from an electric shock. IT WONT !!
They are a useful aid towards safety in that they can help reduce the possibility of a fatal shock.
But please refrain from telling people they prevent electric shock, and choose your words wisely.
Sorry guys rant over.
Click to expand...
listen bald...
i dont (rely on magic)

that boiler gets cross bonded....
 
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Here's something to consider: I've taken a hand > hand (cross the chest) belt at 400V due to another 'electricians' incompetence and am alive to tell the tale purely due to the RCD, of that I have no doubt.

HOWEVER, those few milliseconds before it tripped allows a good few cycles to flow through you, and it bloody hurts, no if's no but's. Your muscles are bruised for days to come, your breathing gets affected, your heart likely goes into arrhythmia even if it self recovers afterwards. I was fortunate to be very fit and healthy so the only outcome was that someone got sworn at incredibly loudly, but I can completely see the same thing having floored an elderly person.

What we work with KILLS. Plain and simple. It is a raging beast which we have learnt to cage and contain, domesticate and 'make safe'. We are not electricians we are lion tamers - let loose the lion and all hell breaks out.

This is why the world does not need novice lion tamers aka Electrical Trainee's, it needs proper well trained ring masters.
 
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Rockingit said:
Here's something to consider: I've taken a hand > hand (cross the chest) belt at 400V due to another 'electricians' incompetence and am alive to tell the tale purely due to the RCD, of that I have no doubt.

HOWEVER, those few milliseconds before it tripped allows a good few cycles to flow through you, and it bloody hurts, no if's no but's. Your muscles are bruised for days to come, your breathing gets affected, your heart likely goes into arrhythmia even if it self recovers afterwards. I was fortunate to be very fit and healthy so the only outcome was that someone got sworn at incredibly loudly, but I can completely see the same thing having floored an elderly person.

What we work with KILLS. Plain and simple. It is a raging beast which we have learnt to cage and contain, domesticate and 'make safe'. We are not electricians we are lion tamers - let loose the lion and all hell breaks out.

This is why the world does not need novice lion tamers aka Electrical Trainee's, it needs proper well trained ring masters.
Click to expand...
no....
due to your own incompetance...

so just who told you to handle any 2 phases simultaneously?

come on...this is pis poor practice...
 
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baldsparkies said:
Old people tend to come from a generation of trust and being able to take people at face value.
Sadly those days are on the decline.
Telling anyone let alone the elderly that an RCD will protect them from an electric shock is plain wrong.
Electricity is dangerous and needs to be treated with respect, end of.
And no amount of wonder devices, over hipe, or BS about what an RCD can or cant do is going to change that.
All I'm saying is an RCD wont protect from shock. And there is no way you or anyone else should be saying anything different.
If you do, then you are giving bad advice, and leading people to believe the RCD can do something that it clearly cannot.
Sorry but to me this is just about common sense, and taking on board your responsibilities as a professional.
Click to expand...
and whats up with being noble?
 
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GLENNSPARK said:
no....
due to your own incompetance...

so just who told you to handle any 2 phases simultaneously?

come on...this is pis poor practice...
Click to expand...

It's kind of you to enquire what is what that actually happened. Had you had done so then you'd quickly retract that comment. The world is a big place.
 
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The key word most people miss/forget when talking about RCD protection is FATAL. In properly designed circuits, 30ma RCDs will usually prevent fatal electric shocks, but that is by no means guaranteed in very young/old/unhealthy people. It certainly does no harm to remind those who think RCDs are fail-safe in every scenario and for every customer, that they are living in La La Land!
 
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Actually the 30mA RCD value is a compromise between safety and nuisance tripping that Europe has basically adopted for socket outlets and the like. We use 10mA for many of our outlet circuits within the hospital buildings, as the sick, the very young and older people are far more susceptible to shock risks than a typical healthy body... Even 10mA RCD's are no guarantee against receiving a fatal shock....

It's far too common for today's sparks to think of RCD devices as cure all devices especially to overcome severely deficient Zs values!! They don't ever seem to think of what happens when and if an RCD fails, which by the way, is far more often than most will imagine!!!


The crux of this thread, is the often proclaimed view that RCD's protect against electric shock, which we all know(or should know) they Do Not, they only limit the time a person is in direct, or indirect contact with the fault. They Do Not limit current as such (which is why you test at both rated value and at 5X rated value). So if electricians are going round telling customers that RCD's will protect them from electric shock, it is ''THEY'' that are Wrong!!!
 
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Rockingit said:
It's kind of you to enquire what is what that actually happened. Had you had done so then you'd quickly retract that comment. The world is a big place.
Click to expand...

more details would be nice. even if as a warning not to trust other people where your own life/safety is concerned.
 
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telectrix said:
more details would be nice. even if as a warning not to trust other people where your own life/safety is concerned.
Click to expand...

I didn't tell the story purely not to hijack the thread!

It was a set of circumstances which you wouldn't normally find in an everyday installation: in touring/events world everything is modular and 'rubber box distro' based - basically a plug and play approach using a mass of heavy ceeform and so on. I was working on an event overseas where there were a whole bunch of brand new brass BC holders on flex been installed (using a 16A ceeform system) into the roof of a large marquee for effect with clear GLS's. Anyway, they didn't work when turned on below at the MCB so up I went up the ladder to have a look, and couldn't immediately see anything wrong so unplugged one and brought it down to ground level. Plugged it direct into another 16A outlet and went and got the meter to see what was on the pins. So I'm holding this thing in one hand, and reach over to grab my test-stick with the other, and brush onto the aluminium edging strip which is fitted onto most flightcases to protect the edges and corners. WALLOP!! It turned out that some wiring-monkeys had gotten their colours mixed up on the cables and the brass BC I had in my hand was wired L to cpc (and I hadn't felt it due to insulated ladders and work boots) and the feed cable onto that dis board had also been cross wired Ph to the E which in turn was also bonded to the cabinet strip). Somewhere in that equation I must have been passing enough to a genuine earth path somewhere to have upset the upstream RCD.
 
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'Additional protection', better with than without ;)

And a surprising amount of faulty RCDs seem to be down to a lack of routine testing. I've read a few cases of RCDs failing on RCD testing then functionally perfectly well after it has been manually tripped and reset
 
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Fin170 said:
'Additional protection', better with than without ;)

And a surprising amount of faulty RCDs seem to be down to a lack of routine testing. I've read a few cases of RCDs failing on RCD testing then functionally perfectly well after it has been manually tripped and reset
Click to expand...

If the RCD fails on manual test, it fails test.
It must not be put back into service, how can you tell that it will not fail again, it has failed once, once is enough to kill someone.
 
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Out of interest....all you guys that carry out EICR ......how many RCD's do you fail as they do not operate within time limits or not at all. I was told recently that 7% RCD's fail! Not good if you are receiving a shock.
 
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netblindpaul said:
If the RCD fails on manual test, it fails test.
It must not be put back into service, how can you tell that it will not fail again, it has failed once, once is enough to kill someone.
Click to expand...
it states quite clearly that if the manual test (test button) fails first time round...then its a fail....
regardless of the 1/2, 1 & 5 values...
 
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Archy Styrigg said:
Hahahahaahaaa...FULL story, please!!! :smilielol5:
On here will be absolutely fine. :21:
Click to expand...
OK..
what happened was i was stood on a wheely bin to change an outside light..all because the dummy i was working for had left the ladders on another job...
first time it was OK...
then i had to go get something...
got back on the wheely bin and was just running the screws in when it went from under me..
now we all know that wheely bins are not that high but it was the way i fell...
shattered my ankle (both sides)..
i have metal plates on each side and some of the screws fixing it ar 50mm long...
theres something like 12 screws in each side...
all back to normal now but i was off for 8 weeks....
i`m lucky to be walking at all really...and when its damp weather it sometimes plays up...
 
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Andy78 said:
One thing that was impressed upon me during my training is that although there is an accepted resistance for the human body, this can vary dramatically from person to person, obviously changing shock risks at different levels. An older person with a weaker heart for example can be more susceptible to fibrilation at lower amperage levels.
Hence the effectiveness of a 30mA RCD depends on the situation.
Click to expand...

GN7 table 1.1 gives the "Total body impedances (Zt) for a current path hand-to-hand" for a human.

@ 225V (from the book) 5% of the population has a Zt of 775 Ohms

50% has 1225 Ohms

95% has 1900 Ohms

Think of these figures when you next get a belt protected by an RCD. I've had a shock earlier this year from another sparks cock up and I must be in the 1900 Ohms range of body Zt, it was a hand to hand shock and I did'nt die BUT the circuit was protected by and RCD and it did'nt trip??? Full test on the RCD and it was fine????


Older people, people with medical conditions etc may still receive a fatal shock. RCD's are not the miracle cure for everyone. Lets get that straight from the start. Yes they are good but they are not to be sold as "a shock free device".
 
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GLENNSPARK said:
OK..
what happened was i was stood on a wheely bin to change an outside light..all because the dummy i was working for had left the ladders on another job...
first time it was OK...
then i had to go get something...
got back on the wheely bin and was just running the screws in when it went from under me..
now we all know that wheely bins are not that high but it was the way i fell...
shattered my ankle (both sides)..
i have metal plates on each side and some of the screws fixing it ar 50mm long...
theres something like 12 screws in each side...
all back to normal now but i was off for 8 weeks....
i`m lucky to be walking at all really...and when its damp weather it sometimes plays up...
Click to expand...


Glenn, I took the Mick at the time. I wont rib you on here for making a daft decision when you was in a rush. BUT I still find it funny and I will take the Mick at any opportunity you bloody idiot lol, pmsl.
 
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Paul.M said:
GN7 table 1.1 gives the "Total body impedances (Zt) for a current path hand-to-hand" for a human.

@ 225V (from the book) 5% of the population has a Zt of 775 Ohms

50% has 1225 Ohms

95% has 1900 Ohms

Think of these figures when you next get a belt protected by an RCD. I've had a shock earlier this year from another sparks cock up and I must be in the 1900 Ohms range of body Zt, it was a hand to hand shock and I did'nt die BUT the circuit was protected by and RCD and it did'nt trip??? Full test on the RCD and it was fine????


Older people, people with medical conditions etc may still receive a fatal shock. RCD's are not the miracle cure for everyone. Lets get that straight from the start. Yes they are good but they are not to be sold as "a shock free device".
Click to expand...
it aint a constant paul...
depends on moisture of skin content as well...
 
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Paul.M said:
Glenn, I took the Mick at the time. I wont rib you on here for making a daft decision when you was in a rush. BUT I still find it funny and I will take the Mick at any opportunity you bloody idiot lol, pmsl.
Click to expand...
well..
whats done is done....

its back to normal..ish now....

i must say i was pised of about it at the time though
 
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what people should remember as well is even though RCDs have ommitted the need for crossbonding of boilers it would be wise to do so....
call it backup...
 
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GLENNSPARK said:
OK..
what happened was i was stood on a wheely bin to change an outside light..all because the dummy i was working for had left the ladders on another job...
first time it was OK...
then i had to go get something...
got back on the wheely bin and was just running the screws in when it went from under me..
now we all know that wheely bins are not that high but it was the way i fell...
shattered my ankle (both sides)..
i have metal plates on each side and some of the screws fixing it ar 50mm long...
theres something like 12 screws in each side...
all back to normal now but i was off for 8 weeks....
i`m lucky to be walking at all really...and when its damp weather it sometimes plays up...
Click to expand...

Hahaha, sorry but that's funny, until I read to the bit about your ankle that is...:wheelchair:

Fair play for owning up to it though.
One guy I worked with took a tumble from a few feet off the ground and bent his wrist over. Turned out he had borrowed a section of ladder from the builders on site, the top section from the type of ladders with wheels on that you can roll up a wall as you extend them. From one of the labourer's reports the daft bugger only walked up them with the wheels at the bottom. Would he heck admit it though ! He spent the next three years denying it. Didn't do him any good though, he still got the mickey taken out him.
 
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Engineer54 said:
Actually the 30mA RCD value is a compromise between safety and nuisance tripping that Europe has basically adopted for socket outlets and the like. We use 10mA for many of our outlet circuits within the hospital buildings, as the sick, the very young and older people are far more susceptible to shock risks than a typical healthy body... Even 10mA RCD's are no guarantee against receiving a fatal shock....

It's far too common for today's sparks to think of RCD devices as cure all devices especially to overcome severely deficient Zs values!! They don't ever seem to think of what happens when and if an RCD fails, which by the way, is far more often than most will imagine!!! In case you have forgotten,you were recently falling over yourself to congratulate an Ra of 15 ohms,which in my world is totally reliant on an RCD to disconnect an earth fault.


The crux of this thread, is the often proclaimed view that RCD's protect against electric shock, which we all know(or should know) they Do Not, they only limit the time a person is in direct, or indirect contact with the fault. They Do Not limit current as such (which is why you test at both rated value and at 5X rated value). So if electricians are going round telling customers that RCD's will protect them from electric shock, it is ''THEY'' that are Wrong!!!
Click to expand...

Spinks said:
But then you have people who still think it's ok to stick a RCD in when a protective device doesn't meet it's disconnection requirements!
Click to expand...
@Spinks
It can be OK. I've quoted this instance before,but will again as it is a good illustration of when an RCD can be used to meet disconnection times.
Had an exising ring circuit in a school serving a number of computers all run through a master switch in the classroom which the teacher would hit at the end of the day to kill the PC's.Inevitably the number of PC's increased to an extent that on the morning switch on the starting surge would sometimes trip the 32a type C breaker in the DB.It was possible to cure this very cheaply by fitting a type D only because an RCD was present which met disconnection times.The Zs was high for a type D...but not by much,dont forget that in the unlikely event of rcd failure the D curve breaker will still operate,but just outside the required 0.4s.
 
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RCD'S and MCB'S are like airbags and they should all be done away with immediately!It has been proven that people with modern cars take more risks because "if I hit anything the airbag will protect me" .Exactly the same with electrics,"if I get it wrong the thing in the box will trip". I had one earlier this week,a bloke hanging a cupboard had hit a lighting cable and quote " there was a bang and the thing in the box tripped,I turned it back on and the lights came on,it was alright until I squirted some gripfill into the hole and the other thing tripped and won't reset" He'd gone between live and earth,severing the earth and nicking the live,this tripped a 6A mcb,which reset when he removed the drill,the gripfill caused a short which tripped the rcd.The irony is that if the rcd had reset he'd have been quite happy to leave it with a damaged cable.
 
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phil d said:
RCD'S and MCB'S are like airbags and they should all be done away with immediately!It has been proven that people with modern cars take more risks because "if I hit anything the airbag will protect me" .Exactly the same with electrics,"if I get it wrong the thing in the box will trip". I had one earlier this week,a bloke hanging a cupboard had hit a lighting cable and quote " there was a bang and the thing in the box tripped,I turned it back on and the lights came on,it was alright until I squirted some gripfill into the hole and the other thing tripped and won't reset" He'd gone between live and earth,severing the earth and nicking the live,this tripped a 6A mcb,which reset when he removed the drill,the gripfill caused a short which tripped the rcd.The irony is that if the rcd had reset he'd have been quite happy to leave it with a damaged cable.
Click to expand...

But you have to balance that against the number of deaths and injuries RCD's and airbags have prevented...the pro's outweigh the cons. If I have a prang I'd have it in a car with an airbag every time...and if I'm getting a belt I would rather have an RCD in circuit than not.
 
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wirepuller said:
But you have to balance that against the number of deaths and injuries RCD's and airbags have prevented...the pro's outweigh the cons. If I have a prang I'd have it in a car with an airbag every time...and if I'm getting a belt I would rather have an RCD in circuit than not.
Click to expand...
yes but ask yourself this one,if you drive like a --- on an icy road in winter,would you drive the same way if I removed your airbags?
 
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GLENNSPARK said:
well..

i must say i was pised of about it at the time though
Click to expand...

Yes, I remember.



Talking about working at heights, I'm doing a job next week where I've got a 50ft boom arm cherry picker. I need someone I can trust on the ground to operate the dead mans switch if needed, and also to get the bloody general public away from where we are working. Do you fancy it at a decent rate? Up to you Glenn.



We may have had a falling out on here in the past, but Glenn is someone I can trust on site. You are more than welcome to "get my back" in a difficult working environment.

No wheely bins are involved pmsl. (was it a black bin or a recycle bin lol).
 
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DONT RELY ON RCD's PLEEEEESE.
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