PD 6662:2017 lists a technical specification for active infra-red beams in sub-clause 3.3: • CLC/TS 50131-2-9 Alarm systems – Intrusion and hold-up systems – Part 2-9: Intrusion detectors – Active infrared beam detectors It appears, as a result of using PD 6662:2017, that it may not be possible to obtain active infra-red beams that are compliant with this technical specification (TS 50131-2-9). A number of active beam manufacturers have informed us that some requirements of the TS are difficult, if not impossible, to achieve so 3rd party certification could not be achieved. If you are unable to obtain active infra-red beams that comply with TS 50131-2-9, you may instead use active infra-red beams that have a claim of compliance made by their manufacturer to BS 4737-3.12:1978 and further assess its compliance to the applicable requirements of BE EN 50131-1 and BS EN 50130-5. The manufacturer should then issue a statement that the device “is suitable for use in systems installed to conform to PD 6662:2017 at Grade N and environmental class Y.” This is a temporary concession pending improved supply of compliant product which may coincide with a transition of the technical specification to a European Norm (EN standard) Note: Infra-red beam sets that incorporate a transmitter and receiver contained in the same housing which use a reflector to direct the beam back to the integrated transmitter/receiver device must not be used as part of a PD 6662:2017 intruder and hold-up alarm system.