Power cut at your company? What to do in the first hour

First find out whether only your site is dark or the whole street. If only you are, check the main switch, the residual-current device (RCD) and the fuses. If the neighbours are dark too, check the outage map of your grid operator and report it. Then protect people, stock and data, and restart in stages. Our guide to the right emergency power supply for your business compares UPS, generator and battery for the cuts that keep coming back. Business battery systems take over within milliseconds, so the first hour stays an ordinary hour.

The lights go out in a workshop, a shop or a barn. "Is it just us, or the whole street?" is the first thing everyone asks. The screens are black, the machines have stopped, the cold room has gone quiet. And five people look at you for the answer.

What costs time is not the cut itself, but the wrong first quarter of an hour. Some sites wait for the grid operator while a tripped RCD is the only problem. Others reset the same breaker three times on a fault. Some switch everything on at once when the power returns, and damage what the cut spared. And an improvised generator can put voltage on a grid where technicians are working.

A site in Maasmechelen shows how it can be different. The customer already had a generator for emergencies, but it stood idle. Our semi off-grid system of 24 kVA with 30.8 kWh of battery made it useful. The customer chooses the grid or the generator to charge its own system. In our media section you will also find a video about a back-up system for an airport control tower.

Is a power cut at your company on the grid or in your own installation?

Look outside first. If the neighbours, the street lights and the rest of the business park are dark too, the cut is on the grid. If only your building is dark, the cause is almost always behind your own meter. Fluvius and ORES both start with that check.

What does it mean when the RCD or the main switch in your company trips?

A tripped RCD or main switch means your own installation cut the power, usually because of a faulty device or too much load at once. The grid operator cannot fix that for you. Brussels Environment (Energuide) describes the main RCD as the large switch with a test button, often marked 300 mA.

ORES gives a simple order: switch off the main switch, the RCD and then the fuses, and switch them back on. Fluvius adds the rule that matters most. If a breaker trips again immediately, the fault is in your own installation: call an electrician. Do not keep resetting it, because each reset sends the same fault current through the same cable.

In a company, the usual suspects are easy to list. A pump with moisture in it, a damaged extension cable, a welding set or a machine that was just switched on. Unplug what you suspect, reset once, and switch devices back on one by one to find the culprit.

Where can you see whether there is a power cut in your area?

Each Belgian grid operator publishes its current power cuts on its website. Fluvius shows current, planned and solved interruptions on a map that is updated every 10 minutes. If your outage is not on it and your own installation is fine, report it.

The pages: Fluvius power interruptions, ORES outages and interruptions, RESA report an outage and Sibelga current outages.

What do you do in the first hour of a power cut at your company?

Work through five steps: people, cause, report, protect, decide. Most of them take minutes, and the order matters more than speed.

1. Step 1: Make people safe. Check that nobody is stuck in a lift and that the emergency lighting works. Keep people away from machines that could restart on their own.
2. Step 2: Find the cause. Use the checks above: neighbours, main switch, RCD, fuses.
3. Step 3: Check the outage map and report the cut if it is not listed. Write down the time it started: you need it for the compensation rules.
4. Step 4: Protect stock, data and animals. Keep cold rooms and freezers shut, save what can still be saved, and shut down servers cleanly while the UPS still holds.
5. Step 5: Decide. Does the map give an expected end time? Then choose to wait, to send people home, or to start a generator or back-up system that is ready for it.

Cold rooms and livestock have their own clock. Our article on how long a battery keeps a cold room cold gives the calculation. For pigs and poultry, read how to keep barn ventilation running in a power cut.

What should you switch off during a power cut, and how do you restart?

Switch off sensitive equipment and large machines during the cut, and switch them back on one group at a time. The National Crisis Centre advises unplugging sensitive devices to avoid damage from a voltage peak at the restart. It also advises not to switch everything on at the same time.

There is a second reason to restart in stages. In Flanders, your capacity tariff is based on your highest quarter-hour peak of the month. A careless restart with everything on at once can set that peak. Our article on how the capacity tariff for businesses is calculated explains the effect on your bill.

After the restart, check what does not start on its own: clocks and timers, machines that need a reset, and the cold-room temperatures.

Why does a whole business park lose power at once?

Because the companies on a business park usually hang on the same distribution cables and cabins. One fault on a shared cable or in a shared cabin can darken the whole park, while the next street still has power.

A Belgian forum describes it well: a transformer burnt, a large generator was placed, and the power came back the same day. For the companies on that cable, it did not matter whose fault it was. They all stood still together.

Check one thing about your own park. Some industrial or commercial sites have a closed distribution network, with its own manager instead of Fluvius. The Flemish regulator describes it as a network within a geographically defined industrial or commercial site. On such a site your first call goes to the site manager, not to the grid operator. Ask your landlord or the park management which applies to you.

Are you not sure whether your company is on low voltage or on medium voltage? Our article on what the voltage level of your business changes explains how to tell.

Who may switch your own medium-voltage cabin back on after a power cut?

Only a warned (BA4) or skilled (BA5) person may operate in the high-voltage room, so never let staff reset the medium-voltage breaker on their own. The AREI (the Belgian electrical safety code) sets these rules for high-voltage installations.

When your own cabin trips, the cause can be in the cabin, behind it, or on the grid cable in front of it. Call your high-voltage maintenance company, and check the outage map at the same time. If the grid is down, your cabin will simply come back with it.

Hang the numbers of your maintenance company and the grid operator next to the cabin door. And make sure someone on site knows who is allowed in.

What keeps running during a power cut, and what does not?

Without a back-up system, almost everything stops, including your solar panels. The Synergrid rule C10/11 requires grid-connected solar inverters to disconnect automatically when the grid fails. They keep producing only when a battery system forms a local grid for them.

According to Victron, a MultiPlus-II takes over in less than 20 milliseconds, fast enough to keep computers running. Our article on a manual or automatic transfer switch for your generator explains the gap a generator leaves. Our article on small UPS units or one central battery weighs the two for IT and production lines.

When is back-up power not worth it for your company?

When a power cut only means that people wait for an hour and nothing is lost.

Do you want to know what a cut costs you and what you can claim? Our article on compensation and the real cost of downtime does the sum. Was the cut announced in advance? Then read how to keep your site running during a planned power interruption.

What happens when you ask us to prepare your site for the next power cut?

We start with what must keep running and what it really draws.

1. Step 1: Analysis. We list the critical loads and their start currents. If data is missing, we can measure your consumption first.
2. Step 2: Technical design. We choose the reserve, the inverter power, the changeover and, where useful, a generator as second line.
3. Step 3: Installation and commissioning.
4. Step 4: Monitoring and support. You follow the state of charge and the consumption in our monitoring software.

Our battery systems for businesses range from small SME installations to modular systems up to 1 MW.