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100mA RCDs TT system

Nikkid
Afternoon all,

What is the stance on using 100mA RCDs for TT systems now?

I was under the impression that they are no longer required as long as all circuits were protected by a 30mA RCD within the consumer unit (which in this case they will be).

Just looking for some clarity. 


Thanks! 

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  • 0
    ebee:
    Sparkingchip:

    Why did councils specify 100 mA main switches in consumer units with TNCS earthing back in the late 1970’s, rather than a 30 mA?


    Not a trick question, I do not know why. 


    I have not come across that one Andy, could it be a regional thing






    I have found them all over the country, one sticks in my mind, I drove from Worcester to Morecambe to do a job knowing that the survey photos showed a RCD main switch and when I got there it was a 100 mA.


    Mind you quite often I get sent photos of the CU with the cover closed, so as to retain life’s little mysteries.


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  • 0
    ebee:
    Sparkingchip:

    Why did councils specify 100 mA main switches in consumer units with TNCS earthing back in the late 1970’s, rather than a 30 mA?


    Not a trick question, I do not know why. 


    I have not come across that one Andy, could it be a regional thing






    I have found them all over the country, one sticks in my mind, I drove from Worcester to Morecambe to do a job knowing that the survey photos showed a RCD main switch and when I got there it was a 100 mA.


    Mind you quite often I get sent photos of the CU with the cover closed, so as to retain life’s little mysteries.


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