Many industrial sites still operate with a “run it until it breaks” mindset when it comes to motors, pumps, and gearboxes.
On paper, it seems efficient: no maintenance labour, no spare parts, no wasted time.
In reality, run-to-failure is almost always the most expensive strategy.
The true cost of downtime isn’t the replacement motor — it’s the lost production, emergency response, scheduling ripple effects, and the stress placed on teams and machinery.
This article breaks down the real cost of motor failure and why forward-thinking engineering teams are shifting towards condition-based and preventative maintenance instead.
1. The Myth of “It’s Cheaper to Replace It When It Breaks”
Most plants only calculate visible costs:
- Cost of replacement motor
- Cost of labour to install it
But the hidden costs are often 10–100x higher:
|
Hidden Cost Area |
Example Cost Impact |
|
Production loss |
£5,000–£50,000 per hour, depending on plant |
|
Rush freight / urgent supplier orders |
2–5x normal delivery cost |
|
Overtime for maintenance staff |
+30–50% labour cost |
|
Penalty charges to customers |
Missed delivery deadlines / SLAs |
|
Knock-on equipment stress |
Pumps, belts, conveyors overloaded |
|
Reputational damage |
“Unreliable supplier” perception |
A failed £400 motor can trigger a £40,000 outage.
2. Downtime Cost Formula (Simple Engineering ROI Model)
Cost of Downtime = (Hourly Output Value × Hours Lost)
+ Emergency Labour Cost
+ Emergency Parts/Freight Cost
+ Contract/SLA Penalties
Even 5 hours of unplanned downtime in a packaging line producing £8,000/hr output:
= (£8,000 x 5) + £350 labour + £180 emergency shipping + £4,000 penalties
= £44,530 loss — caused by a single failed motor
Preventative maintenance cost to avoid that failure? Often < £300 per year.
3. Why “Run to Failure” Still Exists (Even When It’s Expensive)
|
Reason |
Reality Check |
|
“We don’t have time for maintenance.” |
You’ll find time when it fails — at 2am. |
|
“Spare motors are expensive.” |
Downtime costs far more than spares. |
|
“The motor has run fine for 10 years.” |
Ageing insulation = silent ticking clock. |
|
“We just don’t have data on condition.” |
Modern sensors cost less than 1% of downtime. |
|
“We only fix things when production stops.” |
That’s not cost control — that’s firefighting. |
4. The 3 Maintenance Strategies Compared
|
Maintenance Approach |
Cost Predictability |
Risk Level |
Total Lifetime Cost |
|
Run to Failure |
✅ Low admin effort❌ Zero cost control |
❌ Highest |
❌ Highest |
|
Planned Preventative (PM) |
✅ Predictable schedules |
✅ Medium |
✅ Medium |
|
Condition-Based (CBM) |
✅ Data-driven, targeted actions |
✅ Lowest |
✅ Lowest (typically 20–40% reduction) |
Most modern factories move from reactive → planned → predictive as they scale.
5. The 80/20 Rule for Motor Maintenance
You don’t need a full digital transformation to reduce breakdowns.
You just need to prevent the top 20% of causes that trigger 80% of downtime.
✅ Check bearing temperature & lubrication
✅ Keep motors clean & dry (dust + moisture = failure)
✅ Standardise spare motor frame sizes across the site
✅ Use vibration trending to detect early misalignment
✅ Review energy data — a rising kW load often means mechanical wear
Small habits → big reductions in downtime.
6. When a Spare Motor Is Cheap Insurance
A spare motor is not an expense.
It is an insurance policy that removes 90% of downtime risk on critical assets.
Ask this question:
🔍 “If this motor failed tomorrow, how much production do we lose per hour?”
If the answer is more than 10x the motor cost, you should already have a spare.
Conclusion
There is no scenario where unplanned failure is cheaper than planned prevention — only scenarios where the hidden cost hasn’t been calculated yet.
Plants that shift from reactive to proactive maintenance don’t just save money — they:
- Reduce stress on teams
- Increase safety
- Improve output reliability
- Strengthen customer trust
- Gain clearer cost control for finance teams
Downtime isn’t just a technical problem. It’s a business performance problem.
