This circular letter introduces NSI Technical Bulletin No. 0059 which describes changes to the recently published BS 8243:2021. This Code of Practice has undergone a full revision. Prescription that provided a barrier to product innovation has been removed, some clauses have been rephrased to add clarity and some requirements within clauses have been moved to more appropriate clauses. The key changes to the Code of Practice includes: • the previous requirement for all intruder alarm systems to use sequential confirmation is no longer a requirement; any single or combination of confirmation method(s) are permitted; • a number of prescriptive methods that set requirements for the design of audio or visual confirmation have been removed to allow product innovation; • the requirement to declare to the response authority when using detectors incorporating two movement detectors of the same technology within a single housing has been removed; • confirmation of hold-up alarm (HUA) by telephone call back by an alarm receiving centre (ARC) is now permitted only for residential premises; • confirmation procedures have changed to accommodate the different processes relating to sequential confirmation or where the confirmation is decided at an ARC; • requirements for alarm handling which is to be included in a new ARC standard, BS 9518, have been removed; and • an option to set/unset the intruder alarm system (IAS) using a remote device has been included. Implementation timescale for approved and applicant companies BS 8243:2021 was published on the 30th of June 2021. There will be a 12-month transition period ending on the 30th of June 2022. During this period, installations can comply with either the 2010 or 2021 edition. Companies will be able to transition to the 2021 edition at any point during this 12-month period. How do I obtain a copy of BS 8243:2021? BS 8243:2021 is available as an outright individual purchase directly from the BSI or at a discounted rate from the NSI or, alternatively, as a download via the NSI approved company BSI Standards on Subscription service. Questions or queries? If you have any questions or queries regarding the implementation of the change, please do not hesitate to contact me.