DONT RELY ON RCD's PLEEEEESE.

[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.

 

[GLENNSPARK]

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".

it aint a constant paul...
depends on moisture of skin content as well...

 

[GLENNSPARK]

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.

well..
whats done is done....

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

i must say i was pised of about it at the time though

 

[GLENNSPARK]

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...

 

[Andy78]

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...

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.

 

[Deleted member 9648]

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!!!

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!

@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.

 

[Guest111]

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.

 

[Deleted member 9648]

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.

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.

 

[Guest111]

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.

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?

 

[Paul.M]

well..

i must say i was pised of about it at the time though

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).

 

[Deleted member 9648]

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?

I might feel a --- but I never drive like one

 

[GLENNSPARK]

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).

sorry Paul...
but i`m busy these days....

theres a young 17 year old lad that comes out with us...he`s good for watching backs...
i`ll have a word with him...if you like...

 

[Paul.M]

sorry Paul...
but i`m busy these days....

theres a young 17 year old lad that comes out with us...he`s good for watching backs...
i`ll have a word with him...if you like...

A seventeen year watching my back? I dont think so mate. Dont care how good he thinks he is.

If you cant do it, I'll get someone else that I can trust.

 

[efficiencyman]

I have clicked on the "like" button for the comments I agree with. In the 53+ years since my electricians apprenticeship and become a qualified lion tamer, I too would uphold this rant for safety`s sake. I have been called to an electrocuted chap, to isolate the supply and make safe for the ambulance crew. Most unfortunate for all concerned, especially wife & 4 young kids, Although it was before RCD`s were introduced, the reliance on such devices must not be taken for granted as with the OP in this thread. I have all to often come accross DIY & immigrant bodge ups of appaling wiring ---- --- cant write it there were no standards let alone common sense.
Also periodic tests of RCD`s & full EICR test reports are vital to safe guard your own reputation & legal obligations.
Another comment, I have come accross several faulty (not tripping at correct rating ) RCD`s which must be EICR reported & notified for urgent replacement. How many of these were fitted without being tested I have often wondered. Profesionalism in our trade is essential, Sadly those days are on the decline, any hint of "cowboy" slap dash for cash must be stamped out. Many on here like to help people, DIY`ers and learners please be compliant & have your work certified or better still have the done by a professional in the first place.

 

[telectrix]

hope you're not going to attempt this until after the storm warnings are over. @50ft. the wind will be awesome.

 

[telectrix]

where's my cherry picker gone?