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The Value of R.C.D.s

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There have been many discussions recently about R.C.D.s, whether they really are necessary, and is an installation necessarily unsafe if it is old and has no, or insufficient, R.C.D. protection.

 

Well consider this please. If you are driving and need to brake hard to save somebody from injury or death does that incident ever get reported. If you knocked somebody over due to having bad vehicle brakes then it might.

 

If an R.C.D. operates correctly and saves somebody from injury or death, does that every get reported? There may have been 10s, 100s or even thousands of cases where an R.C.D. has saved somebody from injury or death, but we will never know the numbers because of a lack of reporting of the cases.

 

Personally I like the idea of R.C.D. protection

 

Z.

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    AJJewsbury: 
     

    314.1 is often cited, but this is about individual circuits, not RCDs, and relates to faults in the Installation not particularly connected appliances.

    Are you sure you don't have an out of date copy of BS 7671? In my copy 314.1 specifically talks not only about RCDs but also protective conductor currents ‘not due to a fault’ - which I presume is referring chiefly to leakage currents from appliances. 314.2 then talks about giving consideration to the consequences of the operation of any single protective device - not just overcurrent protective devices - so would seem to include RCDs too.

       - Andy.

    314.1

    "Every installation shall be divided into circuits, as necessary, to:

    (i) avoid danger and minimise inconvenience in case of a fault.

    (iii) take account of the hazards that may arise from the failure of a single circuit such as a lighting circuit.

    (iv)  reduce the possibility of unwanted tripping of R.C.D.s due to excessive protective conductor currents not due to a fault."

     

    So the general theme is that of reliability and the reduction of inconvenience.  If having multiple circuits aids this situation, then why would we run a whole domestic installation through just one R.C.D which negates this sensible advice?

     

    Z.

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