This circular letter introduces NSI Technical Bulletin No. 50 which describes the changes introduced with the publication of BS EN 50518:2019. BS EN 50518:2019 was published on the 31st August 2019 and it replaces the 2013 editions of BS EN 50518 parts 1 to 3 which the BSI has now withdrawn. The main changes introduced by the publication of the 2019 edition of BS EN 50518 BS EN 50518:2019 has consolidated all requirements from the 2013 BS EN 50518 series consisting of three parts into one document. There are requirements provided for two categories of ARC: Category I is an ARC that monitors security related connections; e.g. CCTV for security, Intruder alarms, Hold up alarms, etc. Category II is an ARC that does not monitor security related connections; e.g. Fire alarms, CCTV for plant control, Social alarms, Lift emergency alarms, Lone worker, etc. Note: The categories are reversed when compared with BS 5979:2007 or BS 8591. Consolidation of the three-part 2013 standards into the single-part 2019 edition has led to many changes to the clause numbering and general standard structure. References to standards throughout the BS EN 50518:2019 have been updated to refer to current editions. Due to poor availability of certified product, difficulty was experienced complying with some of the product standards referenced in the 2013 editions of BS EN 50518 e.g. Door sets, etc. To address this issue, the 2019 edition references more appropriate standards and offers, in some cases, choice for product standards. A number of areas of the 2019 edition have introduced a relaxation of the requirements to enable compliance. Implementation dates New applicants for approval New applicant companies will be audited against BS EN 50518:2019 with immediate effect and any Improvement Needs recorded against clauses of the Standard will have to be satisfactorily addressed before approval can be granted. Where an application for approval to BS 5979:2007 or the 2013 BS EN 50518 series was already in progress with the NSI before the date of this Technical Bulletin, then the approval will continue to progress against BS 5979:2007 or the 2013 BS EN 50518 series. Existing approved ARCs Existing NSI approved companies approved to BS 5979:2007 or the 2013 BS EN 50518 series will continue to be audited against BS 5979:2007 or the 2013 BS EN 50518 series. Existing NSI approved companies requesting approval for a new ARC will be audited to BS EN 50518:2019 with immediate effect and any Improvement Needs recorded against clauses of the Standard will have to be satisfactorily addressed before approval can be granted. How do I obtain a copy of BS EN 50518:2019? BS EN 50519:2019 is available as an outright individual purchase directly from the BSI or at a discounted price from the NSI or, alternatively, as a download via the NSI approved company 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.