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RCDs and types of leakage

Farmboy
Various publications detail the types of earth faults that different types of RCDs can detect - type A catering for induction hobs, for example, and type F for frequency controlled equipment.


It was stated elsewhere that the DC current, for example, injected into the cpc, only occurs during faults, not during normal use. So, are these DC and complex waveforms present in the line and/or neutral and/or cpc in normal use, or just when there's a fault?
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    Some appliances draw DC current from AC mains under normal operation. Vintage radio and TV sets often use a half wave rectifier to obtain DC internaly.

    Hairdyers sometimes use full mains on the heater for full heat, and half wave rectified for low heat. So do some electric blankets.

    Touching the phase conductor INTO the appliance is dangerous, but no more so than touching any other phase conductor. Touching the neutral INTO the appliance should be harmless, but is to be avoided in case of a reveresed supply polarity, open neutral, or non standard supply with both sides live.


    Touching the half wave rectified mains voltage WITHIN the appliance is dangerous, and not all types of RCD will trip in such circumstances.
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    Some appliances draw DC current from AC mains under normal operation. Vintage radio and TV sets often use a half wave rectifier to obtain DC internaly.

    Hairdyers sometimes use full mains on the heater for full heat, and half wave rectified for low heat. So do some electric blankets.

    Touching the phase conductor INTO the appliance is dangerous, but no more so than touching any other phase conductor. Touching the neutral INTO the appliance should be harmless, but is to be avoided in case of a reveresed supply polarity, open neutral, or non standard supply with both sides live.


    Touching the half wave rectified mains voltage WITHIN the appliance is dangerous, and not all types of RCD will trip in such circumstances.
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