This circular letter introduces NSI Technical Bulletin No. 0057 which describes the recently published BS 7273-4:2015+A1:2021. The Code of Practice has been revised to include: • information on good practice, by means of informative text, in relation to electronic locking of main entrance doors to blocks of flats (although this is outside the scope of BS 7273-4); • guidance/recommendations on provision of break glass release controls in places of lawful detention, mental health units in hospitals and care homes or similar premises; • recommendation regarding the weekly testing of manual release controls; and • the introduction of a note regarding the use of relays connected to a fire alarm sounder circuit used to operate a door release mechanism – a practice which is now deprecated. In addition to the revised Code of Practice BSI has also published: Expert commentary – BS 7273-4:2015+A1:2021 – Code of practice for the operation of fire protection measures – Part 4: Actuation of release mechanisms for doors. This document gives reasons for, and useful guidance on, the changes encompassed within BS 7273-4:2015+A1:2021. Implementation timescale for approved and applicant companies As there are minimal technical changes to the standard, both new applicant and existing NSI Fire Gold, Fire Silver, NACOSS Gold and Systems Silver certificated companies, where applicable, will be audited against BS 7273-4:2015+A1:2021 with immediate effect. How do I obtain a copy of BS 7273-4:2015+A1:2021? BS 7273-4:2015+A1:2021 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 Standards on Subscription service. How do I obtain a copy of the Expert Commentary on BS 7273-4:2015+A1:2021? The Expert Commentary on BS 7273-4:2015+A1:2021 is available as an outright individual purchase directly from the BSI or at a discounted rate from the NSI. Questions or queries? If you have any questions or queries regarding the implementation of the change, please do not hesitate to contact me.