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current and the loop impedance will not exceed a figure of 50 V.
Residual current breakers (RCBs), residual current circuit
breakers (RCCBs) and RCDs are one and the same thing.
Modern developments in CB (circuit breaker), RCD and
consumer unit design now make it easy to protect any individual
circuit with a combined CB/RCD (RCBO), making the use of
split-load boards unnecessary.
In domestic premises the use of 30 mA RCDs is required for the
protection of all socket outlets rated at not more than 20 A, for all
circuits in a bath or shower room and for cables embedded in walls
and partitions at a depth less than 50 mm. Socket outlets not
intended for general use, for example those provided for non-
portable equipment such as freezers, etc., are exempt from this
requirement, provided they are suitably labelled or identified.

Applications of RCDs
30 mA

Applications
- All socket outlets rated at not more than 20 A and for
unsupervised general use.
- Mobile equipment rated at not more than 32 A for use
outdoors.
- All circuits in a bath/shower room.
- Preferred for all circuits in a TT system.
- All cables installed less than 50 mm from the surface of a
wall or partition (in the safe zones) if the installation is
unsupervised, and also at any depth if the construction of the wall
or partition includes metallic parts.
- In zones 0, 1 and 2 of swimming pool locations.
- All circuits in a location containing saunas, etc.
- Socket outlet final circuits not exceeding 32 A in
agricultural locations.
- Circuits supplying Class II equipment in restrictive
conductive locations.
- Each socket outlet in caravan parks and marinas and final
circuit for houseboats.
- All socket-outlet circuits rated not more than 32 A for
show stands, etc.
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