Clarke generators and power products

Power cuts are the reason most households start looking at generators, and the scale of the risk is worth understanding first. Electricity North West's emergency planning guidance states plainly that in a serious event "there won't be enough generators to keep everyone powered as more than one million homes, at least 5% of households in Great Britain, will be without power at once"¹. A generator you own, fuelled and ready, is one of the few backup options that does not depend on the network operator reaching your street first.

Clarke is one of the budget names householders search for by brand, but the figures that matter, output, run time, noise and weight, vary model by model, and Clarke does not publish a single set of specifications for its range. What follows is therefore built around what the machine has to do for a home: the independent buying guidance, the safety rules and the connection requirements that apply to any petrol, inverter or diesel generator sold in the UK. Check each figure against the listing or manual for the exact model you are considering.

What the Clarke range covers, and what this page can tell you

Clarke generators sit in the portable, budget end of the UK market: machines bought from tool retailers for occasional use rather than permanently installed standby systems. Because Clarke's published material does not give one specification set for the range, the honest way to assess any Clarke machine is the same way you would assess any generator: by the output rating, the fuel type, the claimed run time and the safety features listed for that specific model.

Two pieces of context help. First, certification: MCS product certification in the UK covers electricity generating products with outputs of up to 50kW⁵, which comfortably brackets everything in the domestic portable market. Second, network capacity: for generating units of 50kW or less, Scottish and Southern Electricity Networks states there are generally no network capacity constraints or reinforcement costs in most areas⁶. A household generator is therefore not fighting for scarce connection capacity; the constraints that matter are the ones in your own home, which the rest of this page covers.

For the wider picture of how generators compare with batteries and standby systems, see backup power for UK homes, and for the machines themselves, portable generators for home backup.

Choosing between petrol, inverter and diesel models

The three fuel and design types serve different households. A conventional petrol generator is the cheapest per kilowatt and the commonest budget choice: independent testing describes a typical petrol-powered machine with multiple outlets, two 230V 13A sockets, a 12V DC outlet and two USB ports². That socket mix tells you what these machines are for: running individual appliances through leads, not feeding a whole house.

An inverter generator trades some output for clean, stable electricity and quieter running, which matters if you are powering electronics. The comparison between the two designs, including how the inverter smooths the output, is covered in inverter generator vs conventional generator, and the fuel trade-offs in diesel vs petrol generator for home backup.

One point of terminology causes confusion and is worth settling here. The "inverters" that grid connection rules such as EREC G98 and G99 refer to are the type-tested units that let generation run in parallel with the public network⁷. A portable generator that simply plugs into an appliance is not doing that, and the connection rules in this page apply only if you connect a generator to your house wiring so it runs alongside, or instead of, the grid supply.

Power output: matching a generator to what you need to run

The first rule is to add up what you actually need, not what you could run. Energy Networks Association's guidance for people preparing for emergencies is to check that any backup generator "meets the power needs and connections you might have to support in an emergency"⁹. In practice that means listing the appliances you would keep running in a cut, a fridge, some lighting, phone charging, perhaps the boiler's controls and pump, and checking both their running watts and their starting surge.

The second rule is to read the rating plate correctly. Independent buying guidance is explicit that the kW, the usable power, will be less than the kVA figure, at about 80% of it². A machine advertised at a headline kVA number delivers less usable wattage than the badge suggests, and the surge rating, the extra power available for a second or two while a motor starts, is a separate figure again. Sizing in detail is covered in what size generator do I need for home backup?, and the basis of the ratings in what power factor are generator ratings based on?.

Run time belongs in the same calculation. Claimed figures from independent testing range from 8.3 hours at a quarter load (a 750W load) to 8.5 hours from a 3 litre tank, up to 11.6 hours on a larger dual voltage machine². Those are claims, not measured results, and they all assume a light load: halve the load expectation and you will be closer to reality.

Key specs to look at before you buy

Beyond the headline output, the specifications that decide whether a generator is usable at home are the ones on the listing and in the manual. Check:

• Rated output in kW and the surge rating, remembering that usable kW is about 80% of kVA²
• Claimed run time and tank size, and the load the claim assumes²
• Socket types and count, since a typical petrol machine offers 230V 13A sockets, a 12V DC outlet and USB ports²
• Weight and handling, if the machine will be moved between storage and use
• Noise figure, if neighbours are close

If the generator will be connected to the house wiring rather than plugged appliances, further documentation applies. Scottish and Southern Electricity Networks requires a schematic drawing showing the generator itself, the name and power rating in kW of any inverter used, live phases, neutral and earth, lockable isolators, and clear demarcation between the network's and your equipment¹⁰. Northern Ireland Networks additionally asks for a harmonics report up to the 50th harmonic for an inverter connected generator, and site location plans at 1:2500 and 1:500 scale¹¹. These are connection requirements rather than shopping-list items, but they tell you what a proper installation involves.

Home use: fuel, noise levels and where to put it

Placement is the safety point that kills people, so it comes first. Northern Gas Networks' carbon monoxide safety advice is unambiguous: "Never run a petrol, diesel or gas generator inside or near a tent, awning, caravan, motorhome or cabin." The same guidance says to keep the machine away from open doors and windows³. Exhaust fumes drift much further than most people expect, and a generator outside but under a window, or beside a door, can still fill a room with carbon monoxide, which has no smell.

Fuel storage is the second practical constraint: petrol and diesel for domestic use are limited in how much you may store and where, covered in storing petrol, diesel and LPG for a generator at home. Noise is the third. Budget conventional generators are loud, and even a quiet model is audible to neighbours, so placement is a balance: far enough from the house and from openings for safety, close enough for leads to reach without daisy-chaining extension cables. Running costs by fuel are compared in generator fuel types and running costs.

Connection is where the rules tighten. NIE Networks states that if you choose to connect your own generation, "this must be done by a qualified professional"¹². The full picture, including why backfeeding into a socket is dangerous and illegal in effect, is in connecting a generator to a house: transfer switches and the rules and can I plug a generator into a wall socket?.

How a generator affects your household's energy self-sufficiency

A generator is genuine independence of one kind: it makes electricity from fuel you hold on site, and it works when the grid does not. The Renewable Energy Consumer Code describes small-scale heat or power generation units as having "the potential to reduce your energy bills, reduce the impact you have on the environment, and maybe even give you the ability to sell your electricity back to the grid", and says they help reduce dependence on large generating plants located far from where you live¹³. Solar Energy UK makes the same point at national scale: "More homegrown energy means greater energy independence"¹⁴.

But a portable generator is a different animal from renewable generation, and the independence it offers is narrower. It does not lower your grid imports in normal running, the way home generation does when the Energy Saving Trust notes that generating your own electricity "lowers the amount of electricity you import and pay for from the grid"¹⁵. It only produces when you fuel it, start it and stand it outside, and it depends entirely on a supply of petrol or diesel that itself has to be stored, rotated and replaced. In a widespread emergency, fuel stations can lose power too, so stored fuel is the real asset.

There is also no grant support for this kind of purchase. In Northern Ireland, official guidance states there is no financial support available for homeowners who generate their own electricity through domestic renewable technologies¹⁶, and generators for backup fall outside support in any case. The honest framing is that a generator buys you resilience during a cut, not lower bills, and the fuel supply chain remains a dependence. The wider trade-offs are set out in backup power and energy independence and backup power costs compared.

Maintenance, storage and routine servicing

A generator that sits untouched for two years is a generator that will probably not start when you need it. The maintenance rhythm is simple: check the oil before every use, run the machine periodically under load, and service it at the interval in the manual. Oil condition is the commonest cause of failure in stored machines, and the automatic low-oil shutdown on many models is a protection, not a substitute for checking.

Storage covers three things: the machine, the fuel and the paperwork. Fuel degrades over months, so store it in approved containers within the legal limits and rotate it, using old stock in the car or lawnmower and replacing it. For the paperwork, Electrical Safety First recommends that you "register all of your electrical appliances so that, in the event of a problem, the manufacturer can contact you"¹⁷, and a generator is no exception: register it, keep the receipt, and record the model and serial number somewhere you will find them in a hurry.

Finally, test the whole arrangement before a cut, not during one. Energy Networks Association's advice to check that backup equipment meets the power needs you would have to support in an emergency⁹ only means something if you have actually run the fridge and the lights from the generator and timed how long a tank lasts in your own use. A twice-yearly test run, logged, tells you more than any claimed figure. Routine care is covered more fully in maintaining and testing backup power equipment.