Is There a Limit on Diesel Storage at Home?

If you keep diesel at home to run a generator through a power cut, there is no set legal limit on how much you may store. Dorset and Wiltshire Fire and Rescue Service states plainly that there is no specific legal requirement on the amount of diesel you are allowed to store at home¹. That is the key difference from petrol, which is capped at 30 litres on non-workplace premises before you must inform your local Petroleum Enforcement Authority¹.

The absence of a limit is not permission to be careless. The same fire service says petrol and diesel are extremely flammable and, if not stored correctly, could start a fire². The rules that matter are about how and where you store it, and about where the generator that burns it is allowed to run. A generator must never run indoors, because the fumes from the engine can be lethal³.

This page sets out what the fire and rescue services and network operators say about storing diesel, siting a generator, choosing between diesel, petrol and dual fuel, and matching output and sockets to what you need to keep running. It also covers what your electricity network operator will and will not do for you during an outage.

There is no legal limit on how much diesel you can store at home

The headline answer is simple: diesel is not capped in the way petrol is. The fire and rescue service guidance for storing fuel says there is no specific legal requirement on the amount of diesel you are allowed to store at home, and asks that you follow the safety guidance around storing it on the government website¹. Petrol is different: you can store up to 30 litres at home or on non-workplace premises without informing your local Petroleum Enforcement Authority¹.

That does not mean any quantity is sensible. The fire service warns that petrol and diesel are extremely flammable and, if they are not stored correctly, could start a fire². Practical storage advice from the same source includes not smoking near where your petrol is stored¹, and, for caravans and mobile homes, not storing fuel under your home or in direct sunlight⁶. For bio-ethanol, the fire service recommends a cool, dry place away from direct sunlight and naked flames, stored in garages and sheds but out of reach of children and pets⁷. The same principles apply to a diesel can: keep it cool, out of direct sun, away from flames and away from children.

If you keep a bulk tank rather than cans, the wildfire guidance for rural properties says to clear at least a three-metre space around any fuel tanks, and to store tanks on non-combustible material such as gravel or concrete⁸. That is written for rural fire risk, but the separation principle is sound anywhere.

Why you might keep diesel: running a generator through a power cut

A generator is a way to keep selected appliances running when the mains fails. Network operators use generators themselves, connecting them as close as possible to the local electricity substation to restore supplies while permanent repairs are completed¹⁰. Depending on how close you live to a substation, that may mean a generator is located very close to your home¹⁰.

For a household, the case for diesel is running time. Which? says diesel generators generally last longer than petrol generators, with long running time, though diesel is more expensive to buy than petrol and can be noisier than petrol alternatives¹². If you expect to run a generator for many hours across a multi-day outage, that longer running time is the reason to choose diesel.

Before you rely on a generator, do the groundwork. Wiltshire and Swindon Prepared says it takes research by you and the advice and expertise of a qualified electrician for a generator to help you¹³. Keep your vehicle's fuel tank at least half full and fill up if you know a power cut is coming⁴, so you are not caught out if you need to travel or collect supplies. And if the generator has been stored with fuel in the tank or carburetor, the maker's guidance is that all the fuel must be drained and the carburetor cleaned to remove debris and clear blockages before you use it safely¹⁴.

Where a generator must never go

This is the section that matters most. Northern Ireland's official storm advice is blunt: never use standby generators indoors, as the fumes from the engine can be lethal³. The Health and Safety Executive advises locating petrol generators and similar equipment outside in well ventilated spaces so that fumes disperse and cannot gather or drift into building openings¹⁶. The maker's own instruction is to keep it outdoors and well away from doors, windows and vents⁵.

Carbon monoxide is the reason. The London Fire Brigade warns that an extinguished barbecue can continue to produce carbon monoxide for many hours after it has been put out, and that the gas can travel through walls⁹. The same logic applies to a generator: running it in a garage, shed or porch, even with the door open, is not safe. Only equipment designed to be used indoors should be brought inside the home³.

Network operators echo the point. NIE Networks advises being careful where you site a generator in case of carbon monoxide poisoning, and making sure there is plenty of air flow around it to supply oxygen and remove the fumes¹⁷.

Diesel, petrol or dual fuel: how each generator behaves

The three fuel types behave differently, and the choice affects how much fuel you store and how you maintain it.

Diesel's advantage is endurance. Which? notes that diesel generators generally last longer than petrol generators with long running time, and that a petrol model it reviewed had a fuel tank capacity of around 20 litres¹². If you are weighing up running time against noise and purchase cost, the trade-off is real: diesel is more expensive to buy and can be noisier¹².

Petrol brings a hard storage cap. You can store up to 30 litres at home or on non-workplace premises without informing your local Petroleum Enforcement Authority¹, in suitable portable metal or plastic containers, one demountable fuel tank, or a combination, as long as no more than 30 litres is kept¹. Store petrol only in approved containers⁵, and do not smoke near where it is stored¹.

Dual-fuel generators give you a second option. The Champion CPG3500E2-DF runs on LPG as well as petrol¹⁸. If you go that route, read the guidance on LPG cylinders and regulators before you buy, because cylinder storage and connection have their own rules.

Size, output and sockets: matching a generator to your home

A generator only helps if its output matches what you want to run. Which? warns that because they are small, portable generators have a limited output capacity, and some models will not power all appliances¹². Work out what you need first: the watts and watt-hours guide explains how to add up appliance loads, and the generator sizing page takes you through the calculation.

Sockets decide what you can plug in. A large three-phase diesel set, for example, lists 2 x 110v 32 amp, 1 x 240v and 1 x 240v 32 amp outlets, plus a 12v battery charging outlet and 415v three-phase and 240v single-phase output sockets¹⁹. Most households need 230v single-phase sockets for ordinary appliances. If you are offered a 110v set, note the maker's warning that 110v is 40-50% lower output in watts than 230v, and that if full power is required on 110v a single-phase 110v-only generator is needed¹⁸.

If you want the generator to feed your home's circuits rather than individual appliances, that is a job for an electrician and a proper transfer arrangement. The maker's warning is unambiguous: never connect a portable generator directly to household wiring or a wall socket, as this can create dangerous backfeed into the electricity network and may cause serious injury, fire or damage⁵. An automatic transfer switch is one route, but the maker warns that the size and type of generator purchased will determine the power delivered to the equipment or consumer unit, so specify the generator correctly in accordance with the appliances or equipment wattage to be powered²⁰. Read connecting a generator to your home's wiring before going further.

For shock protection, Electrical Safety First advises buying an RCD (residual current device) which will cut off electricity if it detects a fault that could cause electric shock; a portable one is a good start, but for even better protection get one built into your main electrics for the house²¹.

What your network operator will and will not do

It helps to know what to expect from the company that runs your local wires. NIE Networks says that where possible it fits a generator at the local substation, and that it does not fit generators in individual homes or businesses²². SSEN says it cannot provide you with a generator, though you can hire small generators from local hire shops, and you must let SSEN know so it can make sure it is safe¹¹. UK Power Networks connects generators as close as possible to the local electricity substation, which may mean very close to your home depending on where you live¹⁰.

Generators are used for temporary restoration while permanent repairs are completed, and for extended repairs the operator orders generators through network partners with a refuelling strategy in place²³. In exceptional circumstances, such as weddings or funerals, Electricity North West does its best to provide a generator to minimise the impact of the power cut²⁴. Generators are only provided in exceptional circumstances, such as for medical needs like oxygen equipment, mobility aids or end-of-life care²⁴.

If you have medical equipment at home, tell your network operator in advance and ask about the Priority Services Register. The medical devices page covers powering equipment from a battery.

After a repair, you may experience a short outage whilst you are being connected back to the network²³. Keep devices charged and use them sparingly to conserve battery power until you can charge them again²⁵.