Discuss DONT RELY ON RCD's PLEEEEESE. in the UK Electrical Forum area at ElectriciansForums.net

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.
 
that should give the " RCDs are god's gift" brigade something to think about.
 
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.

The above scenario would have happened regardless IMO and its in no way a sparks fault.
 
The above scenario would have happened regardless IMO and its in no way a sparks fault.
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%
 
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.
 
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
 
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.
 
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.
listen bald...
i dont (rely on magic)

that boiler gets cross bonded....
 
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.
 
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.
no....
due to your own incompetance...

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

come on...this is pis poor practice...
 
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.
and whats up with being noble?
 
no....
due to your own incompetance...

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

come on...this is pis poor practice...

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.
 
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!
 
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!!!
 
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.

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

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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