Generator Servicing

Regular generator servicing in London is the difference between a set that starts first time during a power cut and one that fails silently when your business needs it most. Generators London has been maintaining commercial and industrial generating sets across Greater London since 2009, working on all makes and models under structured planned maintenance contracts.

Studies show that up to 30% of generator failures are caused by inadequate maintenance rather than mechanical fault (Energy Institute, 2023). Our servicing contracts are designed to catch issues before they become failures, with a documented service record that supports insurance compliance and internal audit requirements.

What Does a Generator Service Include?

A complete generator service covers the engine, electrical systems and cooling circuit. The exact scope varies by manufacturer recommendation and operating hours, but every service we carry out includes the checks below. Our engineers complete a structured service report after every visit, signed and dated for your compliance records.

Engine Checks

Engine checks cover oil and filter change, fuel filter replacement, air filter inspection and replacement where required, coolant level check and anti-freeze concentration measurement, drive belt inspection, and visual inspection for oil or coolant leaks. For sets operating at high hours, we also test compression and check injector condition.

We check fuel quality as part of every engine service. Diesel stored in a static tank degrades over time and can cause injector fouling, filter blockage and hard starting. Where fuel quality is poor, we recommend a fuel polish or tank clean as an additional service.

Electrical Checks

Electrical checks cover battery condition and charge voltage, battery terminal condition, alternator output voltage and frequency under no-load and loaded conditions, control panel self-test, alarm and shutdown function verification, and ATS operation test. We also check the integrity of all cable terminations and confirm that earth connections are secure.

Insulation resistance testing is carried out on sets where the electrical installation has not been tested in the previous 12 months or where the set has been exposed to moisture. Results are recorded on the service sheet and compared against previous readings to identify trends.

Load Test

A load test is carried out at every service using our portable load bank equipment. Running the set under load confirms that voltage and frequency are stable under real operating conditions, that the cooling system can maintain temperature, and that the engine does not exhibit wet stacking. We test to a minimum of 75% rated output and record the results on the service sheet.

For sets that cannot be load tested on site due to access or noise restrictions, we schedule a separate load bank testing visit to confirm full-load capability.

Planned Preventive Maintenance Contracts

Planned preventive maintenance (PPM) contracts take the administration burden away from your facilities team. We schedule service visits in advance, aligned to manufacturer-recommended intervals, and send reminders before each visit so your team can confirm access and any operational constraints.

PPM contracts include priority access to our emergency breakdown team. Contract clients receive preferential response times, with a target of two hours to site across Greater London. All contract maintenance visits are included at a fixed monthly fee, with no call-out charges for emergency visits covered by the contract scope.

Contracts are available on 12, 24 or 36-month terms. To discuss a PPM contract for your generator, request a free site survey or call 0800 000 0000.

Service Records and Compliance

A complete and current service record is a compliance requirement for many regulated sectors including healthcare, food production, data hosting and financial services. Our service documentation is produced in a format that satisfies most insurer and auditor requirements, and digital copies are available on request for inclusion in your asset management system.

For sites that must demonstrate compliance with the Electricity at Work Regulations 1989 or the Management of Health and Safety at Work Regulations 1999, our service reports provide the evidence base for your statutory obligations. We can also produce periodic inspection reports to BS 7671 standards where these are required by your insurer or regulator.

Frequently Asked Questions

How often should a commercial generator be serviced?

Service intervals depend on operating hours and the manufacturer's recommendation. Standby sets that run infrequently should be serviced at least annually regardless of hours run. Prime power sets operating at high hours may require six-monthly or quarterly services. Our engineers assess your specific set and recommend an appropriate interval at the initial survey visit.

Do you service generators you did not install?

Yes. We take on servicing contracts for any generator regardless of brand, age or who installed it. We carry out an initial condition assessment to establish the current state of the set, review any existing service records, and agree a forward maintenance schedule. We have serviced sets that have not been maintained for several years and returned them to reliable operation.

What brands do you service?

Our engineers service all major generator brands including Cummins, Perkins, Caterpillar, FG Wilson, Kohler, Sdmo, Himoinsa, Aggreko and Pramac. We carry OEM and quality-equivalent parts for common models and have access to specialist parts suppliers for older or less common sets. If you have a brand not listed, call 0800 000 0000 and we will confirm our capability.

What is wet stacking and how do you fix it?

Wet stacking occurs when a diesel generator runs for extended periods at low load, causing unburned fuel to accumulate in the exhaust system. It reduces power output and can cause premature wear. We identify wet stacking during the load test phase of every service and recommend a load bank exercise programme to clean the system. A single load bank session at 75% rated output is often sufficient to resolve mild wet stacking.

Can I get a copy of service records for compliance purposes?

Yes. All service records are available in digital format on request. We issue a signed service report after every visit and maintain a copy in our records management system. For compliance audits, we can also provide a service history summary covering all visits for a specified period, which is useful for insurance renewals, ISO certification and regulatory inspections.