Replacing or extending your consumer unit: when is it necessary and what does the electrician do?

The groepenkast (consumer unit or fuse board) is the heart of the electrical installation in your home: this is where the power from the grid operator comes in and is distributed over the circuits that feed sockets, lighting and appliances. As long as everything works, nobody looks at it. Until the induction hob is delivered, the charging point needs to be connected or the circuit breaker trips for the third time that week. Then it often turns out that the unit is decades old, has no room for an extra circuit or does not meet what the current standard requires of a safe installation. This article is about when replacement or extension is necessary, what is involved technically and what you can expect from the electrician and the grid operator. What you may and may not do yourself in the meter cupboard, what NEN 1010 (the Dutch standard for low-voltage installations) generally requires of a home installation and how an inspection works is explained in Am I allowed to install electrics myself; this article goes deeper into the unit itself and the connection.

Signs that your consumer unit is outdated or full

A consumer unit lasts a long time, but the requirements for an installation have been tightened considerably over the years and the power consumption of an average household has risen sharply. The following characteristics indicate that the unit no longer suits the home:

• Fuses instead of circuit breakers. A stoppenkast (old-style fuse box) with ceramic fuses that you have to replace after a fault usually dates from the 1970s or earlier. The unit is not by definition unsafe, but it was never designed for the number of appliances in use today, and there is a good chance that there is no or insufficient residual current protection.
• No residual current device. A residual current device (RCD) cuts the power as soon as leakage current flows away, for example through a person who touches a faulty appliance. In older homes it is sometimes missing entirely, or it only protects the wet rooms.
• A single RCD for the whole home. Then a fault in the dishwasher also cuts the fridge, the lighting and the central heating boiler, and when you are on holiday you depend on a single component. The current standard spreads the circuits over several RCDs (see below).
• No separate circuits for the kitchen, washing machine and dryer. Large appliances should each have their own circuit. If the washing machine shares a circuit with the sockets in the living room, the breaker trips as soon as the kettle and the vacuum cleaner are switched on at the same time.
• Breakers that trip regularly, warm components or a burning smell. A circuit breaker that trips often is a sign of overloading. Discoloured or warm breakers, a crackling sound or a scorching smell are alarm signals for which you call an electrician immediately.
• No free space for an extra circuit. A unit that is full cannot be extended without replacing it or adding a second unit.
• No main switch with which you can isolate the entire installation in one go.
• Old cable colours. Installations with a green phase wire, a red neutral wire and a grey earth wire date from before the current colour code, which has applied since the 1970s (brown for the phase, blue for the neutral, green-yellow for the earth, black for the switch wire). In old installations the colours are moreover not always correct, so measuring remains necessary. Old colours are not in themselves a reason to replace, but they do say something about the age of the installation.

The more of these points apply to your unit, the stronger the advice to have an electrician carry out a survey. For a home from before roughly 1980 that has never been modernised, the outcome is usually: replace.

What triggers an upgrade: induction, heat pump, charging point and solar panels

By no means every replacement is down to age. More often a new large appliance is the reason. The most important ones:

• Induction cooking. An induction hob requires a lot of power and is generally connected to a Perilex connection (the Dutch standard cooker plug) with a cooking circuit of two or three phases (with a single-phase connection: two circuits on the same phase). A smaller hob with power limitation up to about 3.6 kW can go on one ordinary circuit, but anyone switching from gas to induction often ends up with two or three phases in the kitchen, and therefore with a unit and connection that can deliver that.
• Heat pump. A (hybrid) heat pump needs its own circuit, and a fully electric heat pump with a larger output is often three-phase. Because the heat pump runs for hours on end, it weighs heavily in the total load on the connection.
• Charging point. A home charger for an electric car is preferably connected to a three-phase circuit. Because the charging point, together with the rest of the home, must stay within the connection capacity, load balancing (dynamic charging) is increasingly used: a measurement in the meter cupboard reduces the charging power as soon as the rest of the home draws a lot. That prevents an unnecessary upgrade of the connection.
• Solar panels. The inverter goes on its own circuit with suitable protection; with larger installations spread over three phases. A unit without a free circuit has to be extended for this. The installation must also be registered with the grid operator.
• Air conditioning and electric underfloor heating. Both are heavy consumers that deserve their own circuit; electric underfloor heating on a whole floor can require several circuits. Whether electric underfloor heating is the right choice for your situation at all is explained in Underfloor heating or radiators.
• A renovation or extension with extra rooms, a second bathroom or a workshop in the garage brings new circuits with it and is a logical moment to modernise the unit at the same time.

The common pattern: one new appliance can often still be accommodated, but the combination of induction, heat pump and charging point in a home with a single-phase connection and an old unit in practice means a new consumer unit and a heavier connection.

One phase or three phases: connection capacity and upgrading via the grid operator

The aansluitwaarde (connection capacity) is the maximum current that the grid operator supplies to your home via the main fuse. The most common values in homes are:

Connection capacity	Meaning	Typical for
1 x 25 A	One phase, main fuse of 25 amps	Older and smaller homes without large electrical appliances
1 x 35 A	One phase, main fuse of 35 amps	Homes with somewhat more power, for example electric cooking on one phase
3 x 25 A	Three phases, each with a main fuse of 25 amps	The standard connection for new builds and for homes with induction, a heat pump or a charging point
3 x 35 A and heavier	Three phases with heavier fuses	Very large homes or many heavy appliances; note the much higher periodic network tariff above 3 x 25 A

At the same fuse rating, a three-phase connection delivers roughly three times as much power as a single-phase one and makes it possible to spread heavy appliances over the phases. Whether you need to upgrade depends on the simultaneous power you need, not on the total of all your appliances; an electrician does a load calculation for this. Load balancing on the charging point and smart control of the heat pump can sometimes avoid an upgrade.

Upgrading or switching from one to three phases is work for the grid operator, not for your electrician. You apply for it via mijnaansluiting.nl, the joint portal of the grid operators, or directly with your own grid operator. The grid operator replaces the main fuse(s), the service cable and the meter if necessary, and reseals everything. How the costs are divided: you pay the grid operator a one-off amount for changing the connection, the level of which is regulated by the regulator ACM (Authority for Consumers and Markets) and depends on the new connection capacity and whether the service cable needs to be replaced. The periodic network charges on your energy bill stay the same when you move from 1 x 25 A or 1 x 35 A to 3 x 25 A, because all connections up to and including 3 x 25 A fall into the same tariff category; if you opt for 3 x 35 A or heavier, you move into a higher category and pay a considerably higher fixed annual amount. You pay your electrician for the work on your own consumer unit, which is almost always needed at the same time. The lead time at the grid operator outside congestion areas is on average around two months if no digging is required, but in areas with grid congestion the average rises to almost a year, and if a cable or grid extension is needed, longer still. With the grid operators' Stroomnetchecker (grid capacity checker) you can see per postcode how full the grid in your area is. So submit the application well before the hob or charging point is delivered and coordinate the schedule with the electrician, because the unit must be ready when the grid operator comes.

What NEN 1010 requires of a new consumer unit

For the safety of the electrical installation, the building regulations refer to NEN 1010. Legally, NEN 1010:2015 is still the version designated via the Omgevingsregeling (Environment and Planning Regulation), but the newer NEN 1010:2020 may be applied and is the benchmark in practice; a new or completely renewed consumer unit must comply with that standard, even in an existing home. The main components you will find in a modern unit:

• Main switch. A switch with which the entire installation behind the meter is isolated in a single action. Indispensable for maintenance and in emergencies.
• 30 mA residual current devices. Final circuits with sockets and the lighting circuits in a home are protected by an RCD with a rated tripping current of 30 milliamps. The older standard (NEN 1010:2015, which is still legally designated) allowed a maximum of four final circuits per RCD; NEN 1010:2020 drops that fixed number and instead requires the circuits to be spread over the RCDs in such a way that the sum of the normal leakage currents remains limited (at most 0.3 times the tripping current, so 9 milliamps at 30 milliamps) and that a single fault does not take out the whole home. In practice this still amounts to several RCDs, each with a handful of circuits.
• Circuit breakers or RCBOs. Each circuit gets a circuit breaker that trips in the event of overload and short circuit; the rating (for example 16 amps) matches the wire size of the circuit. An RCBO (aardlekautomaat) combines a circuit breaker and an RCD in one component per circuit. That means more components, but a fault then only cuts that one circuit, which is convenient for the freezer, the central heating boiler, a server or a medical device.
• Surge protection. A device that diverts surges caused by lightning strikes in the area or switching operations in the grid, so that sensitive electronics such as inverters, heat pumps and charging points are not damaged. For new and renewed installations, NEN 1010:2020 prescribes surge protection unless a risk assessment shows that it is not needed; for most homes this means fitting it in practice. When replacing an existing unit it is in any case strongly advised, especially if you have solar panels, a heat pump or a charging point.
• Separate circuits for heavy and fixed appliances. The hob, oven, dishwasher, washing machine, dryer, heat pump, charging point, inverter and electric underfloor heating each get their own circuit. The lighting and sockets are also sensibly spread over several circuits and several RCDs.
• A three-phase unit with a three-phase connection, with an even distribution of the circuits over the phases and a three-phase main switch and main protection.
• Correct cable colours, earthing and labelling. Brown for phase (with three phases also black and grey), blue for neutral and green-yellow for earth; sound earthing and equipotential bonding, and a circuit chart on the unit indicating which circuit feeds what.

The standard covers much more than these points; what is listed above are the components with which you yourself can check a quote and the end result. An electrician who hands over a unit without a main switch, with one RCD for everything or without a circuit chart is not delivering what the standard requires.

What the electrician does step by step

1. Survey. The electrician looks at the current unit, the connection capacity, the condition of the wiring, the number of existing and desired circuits and the space available in the meter cupboard. They ask about your plans: induction, heat pump, charging point, solar panels, extension. Based on that, they advise on one or three phases and on the number of circuits and RCDs.
2. Quote. A clear quote describes the unit (make, number of circuits, number and type of residual current protection devices, main switch, surge protection), the installation of new circuits including cabling and sockets, the measuring and testing, and coordination with the grid operator.
3. Coordination with the grid operator. If the connection needs upgrading, you submit the application and the electrician coordinates the day on which the grid operator comes. Sometimes the electrician installs the new unit first and the grid operator comes afterwards to change the main fuse and meter.
4. Switching off the power. On the day itself, the whole installation is isolated. The electrician works behind the meter; they do not touch the sealed main connection.
5. Removing the old unit and installing the new one. The existing circuits are disconnected and labelled, the old unit is dismantled and the new unit is mounted, usually in the same place in the meter cupboard.
6. Distributing and connecting the circuits. Existing and new circuits are connected, sensibly spread over the RCDs and, with three phases, over the phases. Heavy appliances get their own circuit. Where necessary, new cables are run to the kitchen, the charging point or the inverter.
7. Measuring and testing. Before the power comes back on, the electrician measures, among other things, the insulation resistance, the earth electrode resistance, the continuity of the protective conductor and the operation of every RCD. This is the step that a DIYer can almost never carry out properly, because it requires calibrated measuring equipment and knowledge of the standard values.
8. Commissioning and handover. The power is switched on, all circuits are tested, the circuit chart is filled in and you get an explanation. Ask for a test report or installation certificate showing the measured values; that is your proof for the insurer and when selling the home.

How long it takes: replacing a consumer unit without new circuits is usually half a day to a full day's work. If several new circuits are added for which cables have to be run, it increases to one to several days. The grid operator's lead time for an upgrade comes on top of that separately and in practice determines the schedule. The home is without power for part of a day or longer during the work; take that into account for the freezer, working from home and the central heating.

What you need to arrange yourself

• Grid operator. As the connection holder, you submit the application for an upgrade or a three-phase connection yourself via mijnaansluiting.nl or with your grid operator; the electrician can help you with the technical details. Do it early.
• Smart meter. If you still have an old rotating-disc meter, the grid operator will replace it with a smart meter during an upgrade; since the Energiewet (Energy Act, 1 January 2026), replacing an analogue meter has moreover been a legal requirement and you can no longer refuse it. With solar panels, a meter that records feed-in separately is needed; a rotating-disc meter that runs backwards is replaced by the grid operator.
• Space in the meter cupboard. A modern consumer unit with many circuits, an inverter, a charging point controller and a router need space. For new builds, NEN 2768 prescribes the minimum dimensions and layout of the meter cupboard; in existing homes the cupboard is often cramped and sometimes used as storage space. Empty it, make sure the door can open and discuss with the electrician whether the new unit will fit or whether a second unit next to it is needed.
• Access. The grid operator and the electrician must be able to reach the unit. If you live in a flat, the main connection is sometimes in a central room for which you need the VvE (owners' association) or the managing agent.
• Devices and data. Shut down computers and sensitive equipment properly before the power goes off, and do not open the fridge and freezer unnecessarily.

Accredited installer, quality marks, insurance and safety

Work on the consumer unit is not legally reserved for an accredited company, but it is the most risky part of the installation, and if there is damage due to faulty work, your buildings insurer may ask awkward questions. So choose an accredited installer. In the Netherlands, InstallQ is the foundation that manages the accreditation schemes for installation companies; the former Sterkin and KvINL accreditations have been merged into it. An accredited company demonstrates that it has competent staff, the right measuring equipment and knowledge of NEN 1010, and is checked periodically: InstallQ assesses the company once every four years and, depending on the scheme, also inspects a completed installation on site anywhere from annually to once every four years. In addition, Techniek Nederland is the trade association for installation companies; members work with the Algemene Voorwaarden voor Installatiewerk voor Consumenten (AVIC, general terms and conditions for installation work for consumers) and are affiliated with the Geschillencommissie Installerende Bedrijven (Disputes Committee for Installation Companies). Also ask about the installer's business liability insurance and whether the company provides an installation certificate or test report.

A few safety rules always apply. Only the grid operator works on the main connection, the main fuse and the meter; those components are sealed and breaking the seal is not permitted and may be regarded as fraud or tampering with the connection. An electrician who offers to "just upgrade the main fuse himself" without the grid operator is not a reliable electrician. Replacing a consumer unit is moreover not a job for a handy DIYer: the short-circuit currents are greatest here, a mistake affects the whole home and without measurement you do not know whether the protection does what it should. What you can do yourself on the installation behind the unit is explained in the article on installing electrics yourself.

Checklist for the quote

• Number of circuits now and in the new unit, with room for expansion (a few spare circuits).
• One or three phases, and whether the application to the grid operator has been included in the schedule.
• Number of 30 mA RCDs and the distribution of the circuits over them, or the choice of an RCBO per circuit.
• Main switch and surge protection included.
• Separate circuits for the hob (Perilex), oven, dishwasher, washing machine, dryer, heat pump, charging point, inverter and any underfloor heating or air conditioning.
• New cables and sockets to be installed, including chasing, drilling and making good.
• Measurement and testing after completion, with a written test report or installation certificate.
• Circuit chart on the unit.
• The company's accreditation, guarantee on the work and liability insurance.
• Disposal of the old unit and who deals with the grid operator on the day of the change.
• VAT: a complete replacement of the consumer unit does not fall under the 0% VAT rate for solar panels, not even if it is carried out at the same time as the panels (21 per cent).

You can read more about comparing quotes in general in Comparing quotes.

Maintenance after installation

A modern consumer unit needs little maintenance, but it is not maintenance-free. Press the test button of every RCD and RCBO every month, or at least a few times a year: the switch must trip immediately. If it does not, the protection is faulty and you call the electrician. Keep the circuit chart up to date when circuits are added, keep the meter cupboard dry, ventilated and free of stored items, and have the installation measured again at the next major renovation or when selling. If you ever smell scorching or see discolouration at the unit, switch off the main switch and have it checked before you switch the power back on.

In summary: a consumer unit with fuses, with no RCD or only one, or without room for new circuits is due for replacement, and induction, a heat pump, a charging point and solar panels often turn that into a three-phase connection as well. The grid operator takes care of the connection and the meter, the accredited electrician the unit, the circuits and the measurement. Start with the grid operator, because they determine the lead time, and insist on a test report at handover. On VerbouwPro you post your job free of charge and electricians from your region respond.