SiteIt's 3am. The case erector on line 2 has stopped on a vacuum fault. Your night fitter is on their own. The electrician went home at ten. The spares cage is locked and the person with the code is asleep. The supplier's helpline opens at eight.
On days, this job takes an hour. Someone sees it stop, a second pair of hands turns up, a controls engineer looks over a shoulder, and stores has the cup in five minutes.
On nights, the same fault runs until the day shift walks in.
Nights don't get harder faults. They get the same faults with less of everything around them. Fewer people, fewer parts, less help on the phone, and a body that wants to be asleep.
The fitter is on their own
Plenty of sites run nights with one fitter covering every line. HSE calls a lone worker "someone who works by themselves without close or direct supervision" (INDG73). Your night fitter fits that, even with a full production shift around them.
Being alone slows a breakdown in ways nobody writes down. There's no one to hold the meter leads while they watch the HMI. No one to stand at the isolator. No one to say "have you checked the air?" Every job that needs two people either waits or gets done by one person in a way it shouldn't be.
The same leaflet expects you to plan for this. That means looking at "training, levels of experience and how best to monitor and supervise them", and having systems "to keep in touch with them and respond to any incident" (INDG73). If your night fitter's only lifeline is the shift manager's mobile, that's thin. Our lone working on nights post goes through it in more detail.
Their skills might not match the fault
Look at who covers nights on your rota. Often it's whoever is left after days are filled. A mechanical fitter covering a site full of servos and PLCs. A sparky on a site where most stops are hydraulic.
On days, the gap gets filled by someone else in the building. On nights, it doesn't. The fitter does their best with a fault outside their trade, and the clock runs.
HSE's code of practice for PUWER expects maintenance to be done "by people who are competent to do the work" (L22, paragraph 79). A good mechanical fitter isn't wrong for being out of their depth on a drive fault at 3am. The rota put them there. We wrote more on matching the trade to the kit in fitters, electricians and controls engineers.
The body clock works against you
Here's the part sites don't like to talk about. People are worse at fault-finding at 3am.
HSE's fatigue guidance says accidents and injuries have been found to be higher on night shifts. It also says night workers "are particularly at risk of fatigue because their day sleep is often lighter, shorter and more easily disturbed" (HSE, fatigue).
HSE's shift work guide goes further. It says that where possible, "demanding, dangerous and/or safety-critical work should be avoided during the night and early hours of the morning" (HSG256). Breakdown work on a stopped line is about as demanding as maintenance gets. You can't schedule it for the afternoon. You can plan for the fact it will happen when people are at their lowest.
Watch for the fitter who did a day shift and then stayed on call. HSG256 picks out workers who, after a standard day's work, "have remained on call through the subsequent night or weekend". If your on-call fitter gets called at 2am after a full day, they're tired before they reach the gate. Fault-finding while tired is slow, and slow is the good outcome. Fast and wrong is worse.
Everything else is shut
Count what a day fitter has that a night fitter doesn't:
- a stores person who can find the part, or order it for same-day delivery
- the machine maker's helpline and their field service desk
- the controls engineer who wrote the last PLC change
- an engineering manager who can approve spend on the spot
- the operator who has run that machine for ten years
At 3am, most of that list is asleep or closed. So the night fitter improvises. A part off another machine. A sensor bridged out "for now". A bodge that keeps the line running till six. Our post on reset and run covers what that habit costs you later.
Nobody is watching the clock
On days, a breakdown that drags past an hour gets noticed. The manager walks the floor. Someone asks the right question.
On nights, the shift manager is running production with a stopped line. They aren't an engineer, and they don't want to look like they're nagging. So "one more thing to try" runs on, and the call for help never gets made.
Here's our view. Nights need a hard trigger, written down, that takes the decision off the person on the floor. If it isn't diagnosed by a set time, the shift calls for help. No one has to feel they gave up. We set out how we'd do it in the 30-minute rule.
The cost of the long night
Work it out for your own site. Take your cost per hour of downtime and multiply it by the extra hours a night breakdown runs compared with the same fault on days. Add the overtime to catch up, the trailers that leave short, and the day shift that starts with a backlog instead of a plan. Our cost of downtime post walks through the sums.
Most sites never do this sum, because nights feel normal. A four-hour stop at 2am becomes the cost of running a night shift. It doesn't have to be.
Set nights up to win
None of this needs a bigger team. It needs nights to have the things days take for granted.
Give the night fitter the spares. A small night box of the parts that stop your worst machines: sensors, fuses, contactors, belts, vacuum cups. Not locked behind someone who's asleep.
Give them the information. Manuals, drawings, fault code lists and the last PLC backup, on a tablet or in a folder by the machine. Not on the engineering manager's laptop.
Give them someone to ring. An on-call electrician or controls engineer with a clear rota, and an outside engineer you can get on site when the fault is beyond the shift. Agree it before the night it's needed. Our post on night shift cover covers building that rota.
Give them a clean handover. Five minutes at shift change on what's running badly, what's been bodged and what to watch. The worst night breakdowns are often the ones the day shift saw coming.
What to do on Monday
- Pull the last three months of breakdowns and compare the average time to fix on nights with days.
- Make up a night spares box for your three worst machines and put it where the night fitter can reach it.
- Write down a time trigger for calling help on nights, and brief every shift manager on it.
- Line up who the night shift rings when the fault is outside their trade, before you need them.
* Paragraph numbers refer to L22, fourth edition (2014, amended 2018).