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My war against dual rcd boards

Newfutile
As each (RCD) Residual Current Device must not have more than 30% leakage current on it.
It's hard to see how dual (RCD) Residual Current Device boards can be fitted at all these days.
i come across so many dual rcd boards with solar, evse and heat pumps on them, these have all been recently installed.
i wonder if BS7671 should state: Dual (RCD) Residual Current Device boards shall not be fitted, unless it can be shown (and documented) that they are suitable for the combined leakage currents expected .
otherwise developers will keep specifying them and i will have keep educating them on the many reasons a type A rcd should not be shared with other equipment!.
maybe manuafactuers instructions should also state : not suitable for a shared rcd, for certain equipment.
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  • The question that Graham asked was quite specific:

    ”However, if the lamp is damaged, and the user is being protected against accidental contact with live parts, say after the rectifier, would the type AC RCD operate is perhaps another?”

    in that he said “after the rectifier”, so assume there are some diodes charging a capacitor, which discharges to supply the DC current, and the input current is 25 mA at 230 volts, what is the DC output current and voltage?

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  • The question that Graham asked was quite specific:

    ”However, if the lamp is damaged, and the user is being protected against accidental contact with live parts, say after the rectifier, would the type AC RCD operate is perhaps another?”

    in that he said “after the rectifier”, so assume there are some diodes charging a capacitor, which discharges to supply the DC current, and the input current is 25 mA at 230 volts, what is the DC output current and voltage?

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  • in reply to Sparkingchip

    You tell me. 

    The input is 6.44 W, so the product of the output current and voltage must be no more than that.

    If there is a DC fault, there is no reason to believe that a Type AC RCD would trip, but it might. Graham will correct me if I have misunderstood.

    LED car headlamps glow with a supply of nominally 12 V, so that would give potentially 0.5 A @ 12 V. The figure that I have in my memory for the resistance of a human body finger-to-toe is 2 kΩ, so now we are looking at a current of 12/2000 = 6 mA.

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