ADS

Coby:

So if I am in good contact with earth and I touch a hazardous live line conductor, the trip will trip and I won't feel a thing - correct, no argument there.


 

That's additional protection by RCD.


Nothing at all to do directly with ADS, which relates to Class I equipment and installed wiring systems and accessories only.

 

If I am not in good contact with earth and I touch a hazardous live line conductor, the trip will not trip and I will feel "nary a tingle" - you have obviously never done any electrical installation work in your life!

Regardless of that, if you are not in good contact with Earth or earth, if sufficient current may flow to operate an RCD protecting that conductor, it will operate in a time that should prevent fatal shock in 90-95 % of people, but not in a time that takes away the sensation. If insufficient current flows to operate the RCD, you will still receive a perceptive shock, but again over 90 % of people should not have any lasting physiological effect.


RCDs do not prevent electric shock, they are intended to limit the duration of the shock and hence reduce the impact of physiological effects of that shock.


If the conductor is not protected by an RCD, and ADS is provided by an overcurrent protective device, then you may receive a fatal shock, which is why hazardous live conductors should always be protected by at least basic protection, plus one other method of protection put in place (e.g. ADS or Class II or similar construction).

Coby:

Mr Kenyon that is just a lie!


Duration and magnitude son!


5mA can kill if the duration is long enough and you can't let go of a radiator!

It's not a lie, it's based on information in the IEC 60479-series.


Do you have a technical justification for disputing these standards: https://shop.bsigroup.com/SearchResults/?q=60479&fct=Status&filterBy=CU


 

Coby:

If a little baby crawls over and grabs hold of a nice shiny radiator valve that has become and remained hazardous live because you have told everyone there is no need to earth radiators, who are you going to blame?

The baby

The mother


No, it's you!

That's very interesting.


Consider this scenario.


PME installation. Radiators are served by metal pipework, bonded via main equipotential bonding to the MET. The installation only has a water service, no gas. The water service pipe was changed to plastic, but the internal pipework (including radiators) is still metal, and bonded to the MET.


No problem there?



The kitchen has a flag floor. A baby is touching the radiator in the kitchen, whilst on the flag floor.


A PEN conductor fault occurs in the distribution network supplying the property.


What happens to the baby?

Coby:

If I am not in good contact with earth and I touch a hazardous live line conductor, the trip will not trip and I will feel "nary a tingle" - you have obviously never done any electrical installation work in your life!

So why isn't there a pile of dead birds under power lines? ?

If a little baby crawls over and grabs hold of a nice shiny radiator valve that has become and remained hazardous live because you have told everyone there is no need to earth radiators,

Even the 18th Edition says earth heating systems,

Coby:

So if I am in good contact with earth and I touch a hazardous live line conductor, the trip will trip and I won't feel a thing - correct, no argument there.
Sadly I have much argument  with that assertion.  Depending on contact resistance of course, if there is current flow (you are earthed) you can feel a lot while the RCD trips - that fraction of a second it takes to do its disconnection of supply thing is long enough to realise you cannot breathe, and afterwards can leave you sore and shaking for several minutes - it saves your life, sure, but it is not fun.
If you are not well enough earthed to pass enough current, it does not trip


If I am not in good contact with earth and I touch a hazardous live line conductor, the trip will not trip and I will feel "nary a tingle" - you have obviously never done any electrical installation work in your life!
Again, that really is true  - stand on a plastic bucket, do not lean on the masonry wall, and have only point contact with live, and I assure you will feel nothing, because only a few microamps of displacement current will flow. Unless you are very unusual you will be incapable of feeling 50Hz AC currents less than ~ mA, and yet will be in severe pain much above 10mA.Please do not consider this as advice to try except under carefully controlled conditions.



You're simply trying to invoke chaos theory into a subject that is basically very simple gentlemen. I'm afraid this has nothing to do with  chaos theory  interesting though it is; the physiology of electric shock is a statistical but perfectly well behaved function of the current.

 

And

Coby:

5mA can kill
Again, I disagree, Only if it makes you fall down the stairs or if you are already weakened by other factors. There is a very good reason UK RCDS are set to trip off between 15 and 30mA, and it is to do with the current that healthy people will survive. Of course if you are trapped next to a hot radiator by some other cause, that may well lead to burns, and if enough surface is involved, injury and death.