SiteThe extract fan on the dust collector has been making a noise for three weeks. Everyone's heard it. The operators mention it at handover. Your fitter says it's "always been a bit rough".
Then on a Thursday afternoon the bearing collapses, the impeller rubs the casing, and the line stops because nothing can run without extraction.
The bearing cost very little. The stop cost a shift. And the warning was there for three weeks, in the ears of everyone who walked past.
Most sites already have the early signs of their next breakdown. They just don't write them down.
What condition monitoring actually means
Strip away the sales brochures and condition monitoring is simple. You take the same reading, on the same part, the same way, at regular gaps. Then you watch for change.
That's all. A vibration analyst with a laptop does a more detailed version of the same job. But the trend matters more than the tool. A cheap reading taken every week beats an expensive one taken once a year.
HSE's code of practice for PUWER recognises the approach. Where safety-critical parts could fail and lead to risk, it says "a formal system of planned preventative or condition-based maintenance is needed" (L22, paragraph 75). Condition-based maintenance means you change the part when the readings say it's going, rather than on a fixed date.
The kit you probably already own
You can start with what's in the stores cage. Here's what we'd use, and what each one tells you.
An IR thermometer gun. Bearing housings, gearbox casings, motor bodies, coupling guards. Mark the spot with paint so you shoot the same place each time. A bearing that's a few degrees warmer than last month, with no change in load, is telling you something.
A clamp meter. Running current on each phase of your critical motors. A creeping rise can mean a dragging bearing, a binding conveyor or a fan clogging up. A gap between phases points at the supply or the windings. For more on that, see motor tripping on overload.
A mechanic's stethoscope, or a long screwdriver. Old school, and still useful. Listen to the same bearing every week and you'll learn its normal sound. A rumble, a click or a squeal is a change.
Your eyes and nose. Oil on the floor under the gearbox. Sight glass levels. Belt dust under the guard. A smell of hot insulation at the panel. Damp or dust where it shouldn't be.
A ruler and a tension gauge. Chain stretch and belt tension, measured rather than guessed.
None of these need a contract. Most need a few minutes per machine.
Make the operators part of it
Operators spend every shift next to the machine. They hear the change before your fitters do, because your fitters are somewhere else fixing the last breakdown.
HSE's maintenance guidance suggests "having a reporting procedure for workers who may notice problems while working on machinery" (HSE, maintenance of work equipment). Keep it simple. A card on the machine, a page in the handover book, or a QR code to a form. The rule is that every report gets a reply, even if the reply is "checked, it's fine". If people report a noise and hear nothing back, they stop reporting.
Write it down, or it didn't happen
Here's where most small schemes fall over. The fitter takes the reading, it looks fine, and it goes nowhere.
The reading on its own tells you little. The trend tells you everything. So set up a simple sheet for each critical machine:
- the date
- the point measured, matching a paint mark or a tag
- the reading
- the load at the time, if you can get it
- who took it
- a note if anything was different
A spreadsheet will do. So will your CMMS, if it can hold a reading against a task. Plot it as a line, and agree what change means "plan a job" and what change means "stop it now".
The electrical guidance makes the same point about records. HSE's memorandum on the Electricity at Work Regulations says records "allow useful analysis of equipment condition", even though keeping them is not a legal duty (HSR25, paragraph 69).
Pick your machines
Don't try to monitor everything. Start with the machines that stop the site when they fail, and the ones that take longest to fix. If you haven't ranked your kit, start with criticality ranking.
On each machine, pick the parts that fail. On most sites that's bearings, gearboxes, motors, couplings, belts and chains. The PUWER code of practice gives a good reason to start with bearings. It points out that "failure to lubricate bearings or replace clogged filters might lead to danger because of seized parts or overheating" (L22, paragraph 70).
Ten machines done properly is worth more than fifty done badly.
Know what to do when the line goes up
A trend that climbs is only useful if someone acts on it. And that's the hard part for a small team.
When the readings say a bearing is going, you have a choice. Change it on a planned stop, with the part on the shelf and the right engineer booked. Or wait, and change it at 2am when it collapses, with whoever's on shift and whatever's in stores. The first job might take two hours. The second can take a shift, plus the scrap, the late trailers and the overtime to catch up.
If your team is flat out on breakdowns, the planned job is the one that gets pushed back. Every week it slips, you're closer to the 2am version. That's often the moment to bring in an extra pair of hands, so the planned change happens while it's still planned.
When to spend more
A small budget scheme will take you a long way. At some point it's worth paying for more. Our posts on vibration analysis, thermal imaging for electrical panels, ultrasound for leaks and bearings and oil analysis cover when each one earns its money.
Start cheap. Prove it works. Then use your own trend data to make the case for the next step.
What to do on Monday
- Pick your five most critical machines and paint a mark on each bearing housing and gearbox you want to read.
- Set up one sheet per machine and take the first set of readings this week.
- Put a fault report card on each machine and agree who replies to it.
- Book the reading round into the PPM as a weekly task, with a named owner.
* Paragraph numbers refer to L22, fourth edition (2014, amended 2018), and HSR25, third edition (2015), correct as of 22 September 2026. Check HSE's L22 page and HSE's maintenance guidance for the latest.