Voice alarm fault-finding and repairs
It sounds like a fault has appeared, or keeps coming back, and you want it found rather than guessed at.
A voice alarm fault is best found by measuring, rather than by replacing parts until the panel clears. On an amplifier, the controller or the batteries, that means testing the unit against what it should deliver; on a loudspeaker circuit, the line impedance is read at the amplifier with calibrated equipment and compared with the last reading for that circuit; the run is then sectioned until the reading changes, which places the fault between two known points. The repair is quoted separately from the visit that found it, so the technician who finds the fault does not price the fix.
Report a faultOr call 01273 034 630.
How do you fault-find a loudspeaker circuit?
Start with what the panel says, then look past it. A line fault indication tells you that the monitoring has lost something; it does not tell you what, or where. Three readings do.
- The impedance now, against the impedance before. Every circuit on a maintained system has a reading from commissioning or from the last visit. A circuit that has lost a third of its load has lost a third of its loudspeakers, or a section of cable; a circuit whose reading has fallen has gained load or has a partial short; a reading drifting a little each year can be a joint or a transformer degrading. The number says where to look first.
- The circuit sectioned. The run is opened at accessible points and measured on each side until the reading changes. The fault is between the last good reading and the first bad one.
- The loudspeaker listened to. Continuous line monitoring watches the cable. A single loudspeaker that has failed internally, with the cable looped through it intact, is invisible to end-of-line and impedance monitoring alike, so a zone can report healthy and still be silent above one stairwell. The listening assessment on Recommended and Comprehensive maintenance exists for that fault.
Equipment matters here. An impedance reading is only comparable with last year's if both were taken with calibrated instruments at the same test frequency. All ProAudium measuring equipment is calibrated and traceable to National Measurement Standards.
EOL monitoring vs impedance monitoring: which faults does each miss?
End-of-line (EOL) monitoring tells you a circuit is intact; impedance monitoring tells you what is on it. They are not two points on one sensitivity scale. They catch different fault classes, and each is blind to faults the other finds.
| Fault on a looped-through line | End-of-line | Impedance |
|---|---|---|
| Cable break within the run | Found | Found if enough load is lost |
| Break in the tail past the last loudspeaker | Found | Missed (no load change) |
| Loudspeaker removed so the loop-through breaks | Found | Usually missed |
| Loudspeaker fails internally, loop-through intact | Missed | Missed |
| Most loudspeakers gone, cable loop intact | Missed | Found |
| Short circuit anywhere on the line | Found by the amplifier | Found by the amplifier |
Two consequences for the person responsible for the system. "Which is more sensitive" can only be answered once you name the fault. And neither method is a compliance gap: BS 5839-8 and EN 54-16 monitor the circuit, which is the cable, not the health of each loudspeaker. The dead loudspeaker on an intact circuit is caught by the service regime or not at all.
Where a system is being brought into supervision in stages, the position of each end-of-line device is recorded per circuit, so an interim position does not quietly become permanent. A circuit is fully supervised only when its EOL device sits at the true end of the line.
What happens on a call-out?
When a fault is reported (a zone failure, a panel alarm, a system not performing as expected), we attend, diagnose with calibrated test equipment, and restore service where we can. Every attendance is documented: what was found, what was done, and what action follows.
Response time for Maintenance Contract holders is written into the contract: 4 working hours on Comprehensive, 8 working hours on Recommended, 2 working days on Essential. For systems not under a ProAudium contract, a time is given when you call, and contract holders come first. Cover is London and the South East, plus ships and offshore facilities along the south coast from Dover to Plymouth: the area in which those times can be kept.
A call-out to a system ProAudium has not seen before starts with the same two questions the maintenance visit asks: what did this circuit read when it was commissioned, and what does it read now. Where no commissioning readings were handed over, the call-out reading becomes the baseline.
How are repairs quoted?
Component failure, wiring degradation, circuit faults identified during maintenance or a call out: we locate the fault, replace or rectify, and restore the system to standard. Every repair is documented with the fault cause, the work carried out, and the post-repair verification.
The quotation is separate from the visit that found the fault, and it is written against the reading in the report. You can accept the quote, or hand the findings to another contractor. Either way the report carries the fault's reading, its location and, where possible, a photograph, so whoever prices the fix is pricing the same thing.
Like-for-like replacement is a repair. Anything that changes what the system does, adds to it or alters its cause and effect is a modification, which BS 5839-8 treats differently: the modifying organisation tests the change, updates the as-fitted drawings and issues a modification certificate (BS 5839-8:2023, Clause 41.3). That work is described under Upgrades and additions.
Fault found at a service visit?
If the fault was found during a ProAudium maintenance visit, it is already in the defect schedule with its reading. The maintenance page explains how that record is built: Voice alarm maintenance.
Reviewed on 1 October 2026 by Nigel Williams.