270-271 / 319
11
The Wiring Rules & Building regulations are not the only documents
that need to be consulted, another important document relates to
smoke alarms.
BS 5839-6:2004 Fire detection and Fire
alarm systems for buildings
This Code of Practice has particular requirements for dwellings.
This document makes reference to the power supply to such systems
and mentions RCD’s. The circuit supplying these systems should
preferably not be protected by an RCD. This however is going to be
difficult to achieve if the circuit supplying these systems is buried in
the walls and standard domestic wiring systems are used. Indeed the
supply cables would need to be specially protected in earthed metal
conduit etc. for RCD protection not to be used.
Options for circuits supplying fire or smoke alarms in dwellings
protected by an RCD include:
i. The RCD serves only that circuit. For example with the use of an
RCBO
ii. The RCD operates independently of any RCD feeding socket
outlets or portable equipment
So consideration of these points is necessary during the design stage
and particular care is needed to select the appropriate consumer unit
and wiring system to ensure compliance. BS 5839-6 should always
be studied to ensure that all relevant recommendations are complied
with.
Where RCD protection is needed for smoke detector
circuits one option is to supply that circuit only
The following options, each with their own benefits, can be
considered by the installation designer.
“
”