Standby power, PUWER 1998
What does generator servicing cost?
A 30kVA standby set behind an office and a 1MVA prime mover on a data centre are not the same service, so we do not publish a single made-up average for either. What we publish is the cost-driver table that decides your quote, and one fact worth knowing before you buy: there is no statutory service interval for a standby generator. The duty is to maintain it in efficient working order. The timetable comes from the manufacturer and from how the set is actually used.
No statutory interval
PUWER requires work equipment to be maintained in an efficient state, in efficient working order and in good repair, and sets no service frequency
Risk assessment
how inspection frequency is set: HSE states the need for inspection and inspection frequencies should be determined through risk assessment
1MWth
capacity at which the medium combustion plant permitting regime starts to apply in England and Wales
What happens next
- Tell us about the set: size, role, what you need doing. Two minutes, no account.
- We pass your details to generator service providers covering your postcode, and to no one else.
- They contact you with a price for your actual plant. Compare, choose, or walk away.
Generator Servicing Cost is a free introduction service operated by Ellul Solutions Ltd; we pass your details to generator service providers covering your site, who quote you directly. We may receive a fee from providers; you pay nothing and are under no obligation. We are independent and not affiliated with, endorsed by or acting for HSE, the Environment Agency or any equipment manufacturer, and nothing here is legal or health and safety advice: your maintenance regime and its intervals are matters for your own risk assessment and your manufacturer's schedule.
What sets the price of a generator service, 2026
Last updated
Generator servicing quotes vary more than almost any other plant service, because the phrase covers everything from an oil and filter change on a small standby set to a full load bank test with fuel sampling on a critical installation. Here is what a service provider actually prices, why each item moves the number, and the question that pins it down before you compare quotes.
This is a cost-driver table, not a price list. It is compiled from the way standby generator service work is scoped in the UK in 2026: the set, the service content, the testing regime, the fuel system and the site. We publish no average price because there is no checkable UK dataset of generator service prices, and an unverifiable average is worse than none. The regulatory rows are sourced to HSE guidance on PUWER and to gov.uk guidance on medium combustion plant and specified generators, linked below. For a real number, use the quote form.
| Cost driver | Why it moves the price | What to ask for in the quote |
|---|---|---|
| Set size and engine make | Oil volume, filter cost and labour hours scale with the engine, and parts availability varies sharply between mainstream and niche engine brands. | A price per set, quoted against engine and alternator make, model and serial. |
| Service content, not the service name | Minor and major service definitions are manufacturer and provider conventions. A minor is usually oil, filters and checks; a major adds coolant, belts, injectors or valve clearances depending on the engine. | The parts and tasks list for each visit, and which engine hours milestone each corresponds to. |
| How the set is actually used | A standby set that runs 20 hours a year and a prime mover running weekly reach their hours-based service points at completely different rates, so annual pricing can badly misrepresent the cost. | Servicing planned on run hours as well as calendar, using the controller's hours counter. |
| Load testing regime | Off-load running proves the engine starts, not that it will carry the load. A load bank test needs equipment on site, cabling, and time, and is a separate cost from the service. | Whether load bank testing is included, at what percentage of rating and for how long, and who supplies the load bank. |
| Fuel condition and tank | Diesel degrades and grows contamination in storage, which is the classic reason a set that started fine last month fails when it matters. Sampling, polishing and tank cleaning are separate jobs. | A fuel sample and report as part of the service, and a separate quote for polishing or tank cleaning if the sample fails. |
| Batteries, charger and starting system | Failure to start is most often a battery or charging fault rather than an engine fault, and battery replacement is a routine, predictable, dated item. | Battery age, tested condition and replacement date, rather than a pass or fail tick. |
| Control panel, ATS and interfaces | Automatic transfer switch and control panel testing means proving the changeover under simulated mains failure, which involves the electrical installation, not just the engine. | Whether the ATS and the mains failure simulation are in scope, and who is authorised to switch. |
| Access, hours and permits | Rooftop plant rooms, containerised sets in yards, permit-to-work regimes and out-of-hours testing all add labour before any work is done. | Standard and out-of-hours labour rates, callout charge, and whether travel is billed separately. |
| Environmental permitting and emissions | Larger sets can fall inside the medium combustion plant or specified generator permitting regimes in England and Wales, which brings emissions obligations that a service contract may or may not support. | Whether the provider supports permit compliance and emissions testing, and whether your set is in scope at all. |
- There is no statutory service interval for a standby generator in the UK: PUWER requires work equipment to be maintained in an efficient state, in efficient working order and in good repair, and leaves the frequency to the manufacturer's schedule and to risk assessment (HSE, 2026).
- HSE states that the need for inspection and inspection frequencies should be determined through risk assessment, taking account of the manufacturer's recommendations and the conditions the equipment is exposed to.
- Load bank testing exists because off-load running proves a standby set will start, not that it will carry its rated load; it is a separate purchase from a routine service.
- Stored diesel degrades, so fuel sampling and, where needed, polishing or tank cleaning are a distinct line item on standby generator maintenance rather than part of an engine service.
- In England and Wales the medium combustion plant regime applies to plant of 1MWth or more and less than 50MWth, and the specified generator regime applies to generators up to 50MWth, with exclusions in both cases (gov.uk, 2026).
Cite this page
“What sets the price of a generator service, 2026”, Generator Servicing Cost, https://generatorservicingcost.co.uk/ (updated 2026-08-14). This is a cost-driver table, not a price list. It is compiled from the way standby generator service work is scoped in the UK in 2026: the set, the service content, the testing regime, the fuel system and the site. We publish no average price because there is no checkable UK dataset of generator service prices, and an unverifiable average is worse than none. The regulatory rows are sourced to HSE guidance on PUWER and to gov.uk guidance on medium combustion plant and specified generators, linked below. For a real number, use the quote form.
The questions we get
How much does generator servicing cost?
It is set by the size and make of the set, what is in scope and the site, and there is no published UK dataset of generator service prices we could honestly average, so we do not print one. The biggest swing factors are whether load bank testing and fuel work are included, whether the transfer switch is proved, and your access and out-of-hours requirements. Ask for a price per set with the task list attached.
Is there a legal service interval for a standby generator?
No. A generator is work equipment under PUWER 1998, which requires it to be maintained in an efficient state, in efficient working order and in good repair, and requires any maintenance log to be kept up to date. It does not set a frequency. HSE expects inspection frequency to be determined by risk assessment, taking account of the manufacturer's recommendations and the operating conditions.
Why do generators need load bank testing?
Because starting is not the same as working. An off-load run proves the battery, starter and fuel line. A load bank applies an artificial load so the set can be run towards its rating, revealing cooling, fuelling, alternator and exhaust problems, and clearing the unburnt fuel and oil that build up in lightly loaded standby engines.
Does diesel go off in a standby generator tank?
Yes. Stored diesel degrades and can grow microbial contamination and water, which is a classic cause of a standby set failing when it is finally called on. Fuel sampling, and where the sample fails, polishing or tank cleaning, is a distinct line of standby generator maintenance rather than part of an engine service.
Does my generator need an environmental permit?
It might, if it is large enough. Gov.uk states the medium combustion plant regime applies to plant of 1MWth or more and less than 50MWth, and the specified generator regime applies to generators up to 50MWth, both with exclusions, in England and Wales, regulated by the Environment Agency and Natural Resources Wales. Check the current gov.uk guidance for your set rather than assuming.
Is this quote service really free?
Yes, free to you and with no obligation to accept any quote. We pass your details only to generator service providers covering your site, who quote you directly. We may receive a fee from those providers, which is how the service is funded.