GUIDE

How to write a power outage plan for a town or organisation

A long power outage takes phones, water, heating and card payments with it, one after another. This guide shows what to put in a power outage plan, using the assumptions the UK government works from, with a timeline you can copy.

Last checked 2026-10-30

What the plan has to assume

A power outage plan belongs to the PREPARE stage of the preparedness cycle: written on a quiet day, read later by torchlight, and short enough to work from on paper. It sits under your crisis plan.

The UK’s planning figures are blunt. The National Risk Register 2025 describes a reasonable worst case of total transmission failure across Great Britain, in winter, with everyone lacking a generator losing mains power instantly and without warning. Small pockets could be back within hours, a stable skeletal network within days, and full restoration could take up to seven days, though critical services may take months if equipment is damaged. NESO must be able, by 31 December 2026, to restore 60% of regional demand within 24 hours and all of Great Britain’s demand within five days. That is the aim of a restart from a dead system (Black Start). Storm Arwen in 2021 left just under a million homes without power, some for a week or more.

Plan for two different events. A sudden collapse comes with no notice and no communications. A rota under the Electricity Supply Emergency Code is the opposite: planned, published and repeated, with gaps in which you can recharge and refuel.

What stops, and when

SYSTEM	WHAT THE EVIDENCE SAYS	WHAT TO FIND OUT
Mobile sites	In the 2021 and 2022 storms, batteries at key sites ran down after a number of hours and thousands of cell sites were disrupted.	Which masts cover your sites, and whether any has a generator
Internet and landlines	The Chief Medical Officers’ scenario assumes phone, internet and television disrupted, leaving radio.	Whether your own phone system and broadband have any battery behind them
Water and sewerage	Water and sewage are named as secondary impacts. CMO advice for a national outage says not to flush, because sewers will not be working.	Which pumping stations serve you, and what your water company would deliver
Heating	Cold is the main health risk in the winter scenario, especially for babies, older people and those needing care.	Which buildings keep heat without mains power, since gas boilers usually need electric pumps and controls
Fuel	The Register says fuel must reach priority users and that this would need preparation.	Whether you are a priority user, and how much you hold on site
Payment	The CMO material lists electronic payments among the things that could be lost.	How your welfare points and suppliers work with cash or on account
Chilled food and medicine	A fridge stays cold for about 4 hours; a full freezer holds for up to 48 hours and a half-full one about 24.	Who stores vaccines, insulin or other cold-chain items

Rota disconnection and the Electricity Supply Emergency Code

The Electricity Supply Emergency Code (ESEC, revised April 2026) sets out how supply is shared in a prolonged shortage. The Secretary of State decides, NESO sets the rota, and network operators do the switching. From the decision to the first disconnection should take no more than 48 hours.

Each distribution network is split into 18 load blocks of roughly 5% of demand, and every customer belongs to one block letter. Disconnections run in nominal 3-hour periods, eight in a day. A low-level plan may touch a block for one or two periods around a peak; a higher rota level disconnects more blocks in each period and can run through the day. Changeover can take up to 60 minutes, and network operators receive schedules by 17:30 the day before.

Protected Sites stay on where possible. The list covers tiers such as major hospitals, regionally significant emergency services, water and telecoms, and a site with standby generation does not normally qualify. Ask your network operator for the block letter of each of your sites, and assume you are not protected until you have that in writing.

Critical sites, backup power and fuel

Start with one row per site: care homes, GP surgeries, pharmacies, control rooms, depots, schools used as shelters, and anyone at home on powered medical equipment. For each row, record:

What the site does and who depends on it, in one line.
Load in kW for the circuits that matter, measured rather than guessed.
Backup source, its tank size and hours of running at that load.
Fuel supplier, delivery route and what happens if the supplier is also without power.
Who holds the keys and who can start the generator at 03:00.
Whether a hired or mobile generator can connect, and which plug it needs.

Public information without internet

Plan on radio first. The CMO scripts name BBC Radio 2 and Radio 4 as the most power-resilient services, so your role is the local detail they will not carry: where the welfare points are, when water arrives, which streets are on which rota.

Choose a fixed rhythm, for example notices updated at 09:00 and 17:00 at the same places, so people know when to come back. Paper boards at shops and welfare points work, as do runners and loudhailers for those who cannot leave home. Our guide to planning for a communications failure covers how responders stay in touch, and a PACE plan gives you the order of fallbacks.

Welfare points

A welfare point is a heated room with people who know what is going on. It needs backup heat or power, water, a toilet plan, phone charging, first aid, and a paper register of who came and what they need. Choose buildings in advance, walkable from where vulnerable residents live, and agree who opens each one. Repeat the CMO advice on your notices: generators stay outdoors, at least 6 metres away, with the exhaust facing away from doors and windows.

Sample timeline for hour 1, 6, 24 and 72

HOUR	COMMAND	SITES AND PEOPLE	PUBLIC
1	Open the log on paper. Confirm scope with the network operator if you can reach them. Assume it is long until told otherwise.	Check the sites on the critical list by phone, then in person. Confirm generators started.	First notice on the boards. Tune in to BBC radio.
6	Fix a meeting rhythm. Count fuel and calculate hours left at each site. Stop non-essential loads.	Visit people on the home-medical list. Move cold-chain items.	Open the first welfare point before dark. Second notice.
24	Hand over to a second shift. Ask the Local Resilience Forum for what you cannot source.	First fuel run to priority sites. Check care homes for staffing as well as power.	Water and sanitation advice. Cash and supply arrangements posted.
72	Decide who moves. Plan for a further week, because full restoration may take that long.	Consider moving people from sites where heat or care cannot be kept up.	Mutual aid and volunteers on rota. Daily notices continue.

Yearly check of the plan

Equipment

Run each generator under real load, then measure fuel used.
Test the radios, torches and battery chargers that the plan names.
Check that paper maps and contact lists are current and in the grab bag.

People and paper

Confirm key holders and their deputies by name.
Update the home-medical list and its legal basis.
Run a tabletop exercise on the sample timeline, and put each lesson into the plan with an owner.

Where Sinkaos helps

Sinkaos holds critical sites, kit and fuel in your world model, so the plan is data you can rehearse. Apps work offline, a local field server runs the operation with no internet, and store and forward sends critical text first when a link comes back. None of it replaces radio, paper or a charged battery. See Sinkaos for council emergency teams.

Questions about power outage plans

How long should a power outage plan cover?

Plan for at least seven days. The National Risk Register says full restoration could take that long in the worst case, and critical services may take months if equipment is damaged.

Has Great Britain ever had a total blackout?

No. The National Risk Register says Great Britain has never experienced a nationwide loss of power and that the likelihood is low. It also lists comparable failures abroad.

Will my organisation be a Protected Site?

Probably not. ESEC sets narrow criteria and tiers, and sites with standby generation do not normally qualify. Ask your network operator.