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Too Modest

Former Community Member
Former Community Member
If it can be demonstrated to the scientific community/press/public at large that "the RCD will trip or nary a tingle will be felt", then CBE's, MBE's, Knighthoods or perhaps a Nobel prize will be sure to follow!


This is surely the biggest step forward in Electrical safety since the invention of fuse wire!


In these bleak times the British public needs to hear good news like this.
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    Given that 30mA is enough to kill you, I think "nary a tingle" is wishful thinking.  The standard European 30mA RCD is only intended to be quick enough to break the power before you're dead.


    The Americans seem to prefer a 10mA RCD on high-risk radial circuits.  But they would keep nuisance tripping on UK ring finals that cover half a house.
  • 0
    Coby:

    If it can be demonstrated to the scientific community/press/public at large that "the RCD will trip or nary a tingle will be felt", then CBE's, MBE's, Knighthoods or perhaps a Nobel prize will be sure to follow!

    In these bleak times the British public needs to hear good news like this.


    I maybe wrong but wasn't much of the 1930's 30mA RCD dertermination achieved in Germany experimenting on hospital patients?

    But then what inspired the Nobel prize?

    Legh


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    A few years ago on an electrical safety training course we were allowed to pass a 50 Hz current between a metal tube gripped in our hand and a moist sponge clamp around our wrist on the same side. The current was applied by turning a knob, if you turned the knob the current increased, if you stopped turning the current dropped to zero. 

    Most people stopped at 4-5mA a few got to 6mA. It hurt at those current levels.
  • 0
    When I had my electrical body tests I asked the technician how much current was passing through my body. He said to me it wasn't the voltage, it was the current and the instruments were reading 18mA. Mind you it was being delivered at a pulse and not continuous .

    When in situations like this its a bit like having your teeth drilled without anaesthetic, I know, You remember absoluetely everything.

    Legh
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    I have had a cardioversion (under general anaesthetic) using external paddles. Apparently, from Google, they do not talk about Volts or Amps, but Joules. Generally between 50-360 J.

    Clive

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    The tests were EMG and NCV which basically measured what was happening with my nervous system to various extremities. watching my thumbs twitch for instanst.

    It became rather sore after about 5 minutes.

    Legh
  • Former Community Member
    0 Former Community Member
    Simon Barker:

    Given that 30mA is enough to kill you, I think "nary a tingle" is wishful thinking.  The standard European 30mA RCD is only intended to be quick enough to break the power before you're dead.


     


    How is a standard European 30mA RCD intended to be quick enough to break the power before you're dead?


  • 0
    Coby:
    Simon Barker:

    Given that 30mA is enough to kill you, I think "nary a tingle" is wishful thinking.  The standard European 30mA RCD is only intended to be quick enough to break the power before you're dead.


     


    How is a standard European 30mA RCD intended to be quick enough to break the power before you're dead?




    By tripping in a maximum of 300ms at 30mA, and quicker if the current is higher.


    The biggest worry with electrocution is the heart.  But the clever thing about the heart is that it will automatically restart itself after a brief zap.  That's how hospital defibrillators work - they are rebooting the heart.  So long as the heart hasn't suffered from any permanent damage, you should survive.


  • Former Community Member
    0 Former Community Member
     

    By tripping in a maximum of 300ms at 30mA, and quicker if the current is higher.


     




    It is a well documented fact that as little as 2mA is enough to be fatal, if the duration of the shock is long enough.


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    Not as well documented that it isn't, unless you are considering shocks of 70-80 year duration, when I agree most will have died, but not specifically  from electrocution.

    If you restrain yourself to considering external shocks, those applied through the skin, and ignore shocks during surgery and from deeply penetrating electrodes, as not being typical of domestic shocks, the following curves apply to humans and low frequency AC. The kink between half  a second and perhaps 0.2 of a second relates to the period of a human heart beat. Shocks that are of short duration c.f. a heartbeat are  can be higher magnitude without effect than those that span a heartbeat or more. although this refers to IEC 60479, that in turn is based on the works of Dalziel and others in the 20th century.
    iec shock curves

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