Nigel Williams
Commercial Director, ProAudium
Nigel Williams has been a director of ProAudium since 2014. ProAudium maintains and services emergency sound systems across London and the South East.
He learnt the work on sites that could hardly be more different: stadia, shopping centres, office blocks, ships, oil rigs and theme parks.
His work now covers what happens to a voice alarm system after it is installed. That includes maintenance to BS 5839-8, systems at large venues under BS 7827 and the Guide to Safety at Sports Grounds, and the emergency voice communication systems covered by BS 5839-9. The articles here come from that work. Each one starts from a question that came up on site or in a quotation and works it through against the standard. Every clause is cited so you can check it for yourself.
He also builds the free tools on this site: the standby battery calculator, the Zone Output Estimator and the Martyn's Law checker.
Articles
STI measures the channel, not the conversation
What a Speech Transmission Index figure tells a fire alarm technician, and the four things it never hears.
Annual voice alarm service: what you should see done
A read-do checklist for building owners, 21 items over three pause points, from booking the visit to signing for it.
The noise measurement that shrinks a PAVA quotation
One background noise figure sets every tap, the amplifier and the alarm battery load; measure it instead of assuming it.
Voice alarm panels can cry wolf and still miss real faults
False faults, missed faults, and what to ask whoever maintains your voice alarm.
A 1200 W voice alarm's battery is sized by its quietest 24 hours
Tripling the amplifier power moved the answer less than doubling the standby current.
Changing voice alarm maintainer? The drawings were never theirs to hand over
What the new firm should check first, and which documents the outgoing firm actually owes you.
Twenty-one loudspeakers or one zone: when voice alarm work stops being a repair
Where BS 5839-8:2023 draws the line between repair and modification, and who signs the certificate.
Six assessment points, no misses allowed: the voice alarm intelligibility figures, correctly stated
What BS 5839-8:2023 recommends for speech intelligibility, how it is measured, and when a listening test is enough.
Two services and 52 tests: what a year of voice alarm maintenance should contain
What each six-monthly and annual visit should include under BS 5839-8:2023, and who does the weekly test.
What is PAVA?
One sound system doing two jobs: everyday announcements, and emergency voice messages that override everything else.
Fire follows physics. An attacker reads your procedure.
Message libraries are built for fire, which never reads the plan. Why the emergency microphone is a venue's primary control, and who keeps it ready.
100 V line explained: why the amplifier's power ends up in the loudspeaker, not the cable
Why 100 V line exists, worked through 20 m of Cat 5e: 40 % of the amplifier's power lost in the cable, or 0.4 % on 100 V line.
Peukert's law oversizes your voice alarm batteries
The number hidden in the usual equation, and the line at 20 Ah.
Attention please: the two worst words to start an emergency announcement
The words that open almost every UK emergency announcement came bottom of eight in the study that ranked them.
What battery manufacturers should publish, but do not
The 30-minute discharge figure the calculation needs, and who publishes it.
The worked example that doesn't work
The arithmetic error in BS 5839-8:2023 Annex C, traced term by term.
Your next voice alarm battery quote should be smaller than your last
What the 2023 edition changed, and three questions to ask before you sign.
Questions about an article, or about a system of your own? Contact Nigel.