It’s quite common for people to focus solely on BS 5839 when thinking about PAVA systems, but there’s another important standard that gets overlooked—BS EN 50849:2017.
Unlike BS 5839, which is a code of practice, BS EN 50849 is a specification, meaning it’s mandatory. This standard focuses on sound systems for emergency purposes beyond fire alarms.
Below, I’ve highlighted some key points from the two standards. Both cover the design, installation, and maintenance of PAVA systems.
Also, it’s worth noting a third standard—BS 7827:2019. This one specifically applies to sound systems in sports grounds, large public buildings, and venues. While I won’t dive into that here, the diagram below (from BS 7827) shows that if you’re working on systems for these types of venues, you should begin and end with BS 7827 to ensure compliance.
Both BS EN 50849:2017 and BS 5839-8:2023 provide guidance on emergency sound systems, but they differ in their scope, terminology, technical requirements, and areas of emphasis. Here's a breakdown of the main differences:
1. Scope and Application:
- BS EN 50849:2017: This standard specifically focuses on "Sound systems for emergency purposes" that operate independently of fire detection and alarm systems. It explicitly excludes systems designed for fire emergencies. It also acknowledges its use for non-emergency purposes, such as general sound reinforcement, but highlights its primary function in emergency situations.
- BS 5839-8:2023: This code of practice specifically addresses "Fire detection and fire alarm systems for buildings - Part 8: Design, installation, commissioning and maintenance of voice alarm systems". It explicitly focuses on voice alarm systems (VAS) designed to work in conjunction with fire detection and fire alarm systems to facilitate safe evacuation during fire emergencies.
2. Terminology:
- Acoustically Distinguishable Space: BS 5839-8:2023 introduces the term "acoustically distinguishable space" (ADS), replacing the term "acoustically distinguishable area (a.d.a.)" used in the previous edition. This change emphasises the three-dimensional nature of acoustic spaces.
3. Technical Requirements and Recommendations:
- Emergency Message Generators: BS 5839-8:2023 omits specific requirements for emergency message generators, deferring to BS EN 54-16:2008 for those details.
- Active Noise Cancellation: BS 5839-8:2023 explicitly prohibits the use of active noise cancellation systems to prevent functional system testing.
- Intelligibility Measurement: BS 5839-8:2023 provides updated and more extensive guidance on assessing speech intelligibility, including both subjective and objective methods. It recommends subjective testing in all loudspeaker zones.
- Attention-Drawing Signal Level: BS 5839-8:2023 includes new recommendations for the level of the attention-drawing signal that precedes emergency messages. It should be 6 dB below the peak of the normalised recorded speech signal.
- Networked Systems: BS 5839-8:2023 adopts the term "distributed systems" to encompass a broader range of technologies beyond traditional networking.
- Cybersecurity: Reflecting the increasing importance of data security, BS 5839-8:2023 includes a new clause dedicated to cybersecurity considerations in PAVA systems.
- Loudspeaker Circuit Impedance Measurement: BS 5839-8:2023 includes a new recommendation to measure all loudspeaker circuit impedances annually and investigate any deviations from previous measurements.
4. Emphasis on Practical Application and Maintenance:
- User Responsibilities: BS 5839-8:2023 places significant emphasis on user responsibilities in maintaining the VAS, including routine testing, inspections, record-keeping, and addressing non-conformities. It acknowledges that maintenance technicians may not have expertise in acoustic design, but highlights the importance of their familiarity with clarity and audibility to identify potential issues.
- Logbook Requirements: BS 5839-8:2023 provides detailed guidance on the information that should be recorded in the VAS logbook, emphasising its importance for demonstrating compliance with regulations and assisting with maintenance activities. It allows for the VAS logbook to be combined with the fire detection and alarm system logbook.
In summary: BS EN 50849:2017 offers a broader perspective on emergency sound systems, while BS 5839-8:2023 provides more specific guidance tailored explicitly for voice alarm systems integrated with fire detection and alarm systems within the built environment. The 2023 update to BS 5839-8 incorporates technological advancements, evolving best practices, and a greater focus on user responsibility in maintaining system functionality over time.
Audio Consultant at RH Consulting & Director at Copper Leaf Media
4 个月I agree with Anthony that currently EN 50859 has an identity crisis due to its exclusive non-fire use. However, we do need a standard somewhere that covers non-fire applications such as those discussed in BS 7827. It's also worth noting that I wanted to remove BS 7827 and instead have a large venue annex to BS 5839-8 instead but the rest of the committee disagreed!
Audio Consultant at RH Consulting & Director at Copper Leaf Media
4 个月When we rewrote BS 7827 in 2019, one of the aims was to try and give EN 50849 a place. It enabled us to make BS 7827's role clearer. It tells the user to use existing standards (BS5839-8 and EN 50849) as appropriate, even on a zone by zone basis. In the context of BS 7827, EN50849 is generally to be used for external areas where crowds still need managing but there is no risk of fire.
Managing Director at Vox Ignis Limited
4 个月Nigel, the big problem with EN50849 is at present it cannot be used for fire emergencies- the scope says that. We in epl100 are going to try and fix that for alert/evac systems in high rise residential systems
Systems Engineer at telent
5 个月Another great article Nigel, its discussions like this that helps everyone better appreciate and understand the intricacies of the application of standards in PA / PAVA, thanks.