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Has anyone had experience of a RCD tripping when getting a shock?

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  • 23-03-2020 7:18pm
    #1
    Andy From Sligo
    Registered Users Posts: 11,792 ✭✭✭✭


    has anyone on here in real life ever had a RCD in a consumer box trip by getting an electrical shock and lived to tell the tale?

    They are supposed to trip at 30ms sensitivity I think. I have heard and experienced myself the odd random trip where it had to be reset in the CU but very very rarely - but just wondering IRL what its really like and how well /quick they trip out and work.

    I dont fancy touching a live wire in a socket with my bare hands just to find out if it does trip OK :D
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    #2
    GinSoaked
    Closed Accounts Posts: 1,049 ✭✭✭GinSoaked


    Any decent sparks will have a tester that can test an RCD and give you the actual trip time and current.


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    #3
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    i have, several times. The last time, it lasted about a second or 2 before tripping.

    There is a general belief out there that any contact with a phase protected by one will trip it. That is far from true. It takes quite a strong perceived shock to trip one.


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    #4
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    GinSoaked wrote: »
    Any decent sparks will have a tester that can test an RCD and give you the actual trip time and current.

    I dont think that applies when in contact with a phase and earth, hand to hand for example.


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    #5
    GinSoaked
    Closed Accounts Posts: 1,049 ✭✭✭GinSoaked


    Bruthal wrote: »
    I dont think that applies when in contact with a phase and earth, hand to hand for example.

    Isn't that what the protection is all about? 30mA for 30ms should be less than the normal threshold to kill you.

    I defy anyone to accurately measure time while getting an electric shock.


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    #6
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    GinSoaked wrote: »
    Isn't that what the protection is all about? 30mA for 30ms should be less than the normal threshold to kill you.

    I defy anyone to accurately measure time while getting an electric shock.

    So when someone asks if anyone has tripped an RCD with a real life shock, the answer is, any good sparks can test the rcd?


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    #7
    Andy From Sligo
    Registered Users Posts: 11,792 ✭✭✭✭Andy From Sligo


    Bruthal wrote: »
    i have, several times. The last time, it lasted about a second or 2 before tripping.

    There is a general belief out there that any contact with a phase protected by one will trip it. That is far from true. It takes quite a strong perceived shock to trip one.

    great that's the answer I was looking for - quite a jolt then one would still get then at one or 2 seconds then .

    thats predicting they working and not faulty in the first place. Do they fail in the on position or does a faulty one just keep tripping all the time?


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    #8
    Risteard81
    Registered Users Posts: 2,567 ✭✭✭Risteard81


    GinSoaked wrote: »
    Isn't that what the protection is all about? 30mA for 30ms should be less than the normal threshold to kill you.

    I defy anyone to accurately measure time while getting an electric shock.

    It's not 30mS though. It's 40mS at 5 I delta n (150mA) or 300mS for I delta n.

    The actual current it takes to operate the RCD will be between 50% and 100% of its rated residual operating current, so a nominally 30mA device can operate at any point above 15mA up to 30mA.


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    #9
    GinSoaked
    Closed Accounts Posts: 1,049 ✭✭✭GinSoaked


    Risteard81 wrote: »
    It's not 30mS though. It's 40mS at 5 I delta n (150mA) or 300mS for I delta n.

    The actual current it takes to operate the RCD will be between 50% and 100% of its rated residual operating current, so a nominally 30mA device can operate at any point above 15mA up to 30mA.

    Sorry my mistake haven't had to worry about one in years. Last time I had one tested it did indeed trip at 15mA and the response time was much better than the rating iirc something around 200mAmS - remember at the time being surprised how low the current and fast the speed was compared with the rating. The point is to protect human life so 30mA 300mS is still going to be below the threshold to kill an average person, although I'm sure someone can come up with a scenario where it isn't.


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    #10
    GinSoaked
    Closed Accounts Posts: 1,049 ✭✭✭GinSoaked


    Bruthal wrote: »
    So when someone asks if anyone has tripped an RCD with a real life shock, the answer is, any good sparks can test the rcd?

    While its hard to know what Andy From Sligo was thinking when he wrote his post he seemed to imply the only way to test an RCD was to get a shock, I wanted to make sure he knew that wasn't the case.


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    #11
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    GinSoaked wrote: »
    While its hard to know what Andy From Sligo was thinking when he wrote his post he seemed to imply the only way to test an RCD was to get a shock, I wanted to make sure he knew that wasn't the case.

    I know, Im just having a laugh really. Its one of those days.


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    #12
    Risteard81
    Registered Users Posts: 2,567 ✭✭✭Risteard81


    GinSoaked wrote: »
    The point is to protect human life so 30mA 300mS is still going to be below the threshold to kill an average person

    NO!!!

    It's the 40mS at 5 I delta n which provides additional or supplementary protection - the type we need for protection of human life. It should prevent ventricular fibrillation and save approximately 95% of the population around 95% of the time.


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    #13
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    It is more the speed of disconnection. Whatever current that will flow in terms of electric shock, will not be restricted by the RCD, only the time it flows for, so the RCD more reduces the shock magnitude based on the duration being kept short.


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    #14
    GinSoaked
    Closed Accounts Posts: 1,049 ✭✭✭GinSoaked


    Risteard81 wrote: »
    NO!!!

    It's the 40mS at 5 I delta n which provides additional or supplementary protection - the type we need for protection of human life. It should prevent ventricular fibrillation and save approximately 95% of the population around 95% of the time.

    My bad, sorry but your information about 300mS confused me. So the one of the ones I had tested must have tripped at about 15mA and 20mS on the test, I at least remember it was well below the rating which was something I didn't expect considering the age and the outward condition of the device (dust covered and damp).


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    #15
    Risteard81
    Registered Users Posts: 2,567 ✭✭✭Risteard81


    GinSoaked wrote: »
    My bad, sorry but your information about 300mS confused me. So the one of the ones I had tested must have tripped at about 15mA and 20mS on the test, I at least remember it was well below the rating which was something I didn't expect considering the age and the outward condition of the device (dust covered and damp).

    OK.

    So basically where the RCD is being used for additional/supplementary protection against electric shock (so a maximum rated residual operating current of 30mA) then it must operate within 300mS at its rated residual operating current - I delta n - (or for older British Standard type devices this was 200mS - but for I.S. EN 61008/I.S. EN 61009 devices it is 300mS).

    It MUST NOT operate at half of its rated residual operating current.

    And to provide additional/supplementary protection then it MUST operate within 40mS at 5 times its rated residual operating current - this is the key part to providing protection against electric shock.

    Where an RCD is not providing additional/supplementary protection, e.g. all devices with a rated residual operating current exceeding 30mA then they are NOT tested at five times the rated residual operating current.

    These tests should be conducted on both the positive and negative half-cycles of the sine wave (or 0 degrees and 180 degrees if you prefer).

    Hope this helps.


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