Will I lose power during a smart meter installation?

The interruption is planned, not a fault. It is the unavoidable consequence of working on live metering equipment: the installer cannot swap a meter that is still energised. Everything in the home that depends on mains electricity, including the Wi-Fi router, goes down with it and comes back when the supply is restored.

This page sets out how long the visit takes, what happens during the swap, how to prepare, what the installer should tell you on the day, and what to do if the meter does not behave as expected afterwards. It also covers the point that matters for a household's energy independence: a smart meter still depends on the grid and on a communications network, and the installation itself is a moment of total dependence on the supplier's engineer.

Yes, expect a short power cut: up to an hour while the meters are swapped

The loss of supply is the single most common worry about the visit, and the answer is consistent across the guidance. Smart Energy GB states that during installation the electricity supply will need to be turned off for up to an hour⁷. Its installation process page is more specific: typically 30 minutes for each meter, gas and electricity¹. Which? says the electricity and gas will need to be switched off for around an hour each³.

The range between "30 minutes per meter" and "around an hour each" reflects how the two supplies are handled. The electricity meter change is the one that takes the supply down; the gas meter change interrupts the gas. A household with both meters being replaced should plan for the electricity to be off for up to an hour, and the gas for a similar period, though the two interruptions are usually sequential rather than simultaneous.

The wider installation window is longer than the power cut itself. The Welsh Government's climate action guidance describes installation as typically taking about 90 minutes and being free of charge⁵. The Energy Saving Trust gives the same typical figure of about 90 minutes². Smart Energy GB's own account of a celebrity installation puts it at approximately one hour to install each smart meter⁴. The practical expectation is therefore a visit of one and a half to two hours, of which only part involves the supply being down.

For a household's independence, this is the moment the meter stops being a passive device and becomes a connected one. The supply interruption is short, but the meter that replaces the old one will depend on the national smart meter network to send readings, and on the supplier for its continued operation. The installation is the point at which that dependence is established.

How long the installation takes overall

The visit is usually booked as a single appointment covering both meters. The Welsh Government puts a typical installation at about 90 minutes⁵, and the Energy Saving Trust agrees². Smart Energy GB describes roughly an hour per meter⁴, which for a dual-fuel home means around two hours. The difference between the two figures is largely a matter of whether the estimate covers one meter or two.

Several things extend the visit beyond the meter swap itself. The appointment includes key safety checks, and an in-home display should be offered and demonstrated¹⁰. Installers are also expected to provide energy efficiency advice⁴, and some providers may offer a free energy efficiency inspection during installation⁵. Each of these adds time to the appointment without adding to the power cut.

Access matters as much as the work. NIE Networks advises that the area around the meter should be clear with good access before the installer arrives¹¹. A meter cupboard packed with stored items, or a meter box that is difficult to reach, will lengthen the visit. If the property has unusual circumstances, such as a meter in an awkward location or a supply arrangement that is not standard, the supplier should be told when the appointment is made, or at least several days before the installation³.

For a household, the practical planning figure is a half-day at home. The supply itself is down for a fraction of that, but the appointment has to be attended throughout, and the installer will need to move between the meter position and the consumer unit.

What happens during the swap: old meter out, smart meter in

The visit follows a recognisable sequence. The installer arrives, confirms the meter positions and isolates the supply. The old meter is removed and the smart meter fitted in its place, with the supply off during the changeover. The supply is then restored and the new meter commissioned. Smart meters measure gas and electricity usage and send the data directly to the energy supplier⁵.

The meter being fitted will almost certainly be a second-generation (SMETS2) unit. Cross-compatibility means a smart meter keeps its smart functions across all energy suppliers, so switching supplier does not interrupt them, and SMETS2 is now the meter type used for any new smart meter installation¹². Older first-generation meters are being migrated into the new smart data network or replaced with a second-generation meter by the end of the rollout¹³.

This matters for what happens after the visit. A SMETS2 meter should hold its smart functions through a supplier change. A first-generation meter may lose some smart functionality when the supplier changes¹³, and most first-generation meters are now connected to the central smart meter network and have regained their smart functions, which they should keep if the supplier is switched again; those that cannot be connected need replacing¹⁴.

The wider context is a national infrastructure programme. Smart meters are replacing analogue gas and electricity meters as part of the upgrade of Great Britain's energy system¹⁰, and Ofgem has described the current period as a transition to a new phase in the smart meter programme¹⁵. For the household, the swap is a small event; for the system, it is one installation among many.

Preparing your home for the loss of supply

Preparation is mostly about the hour without power. NIE Networks advises turning off all electrical appliances before the power is switched off, and ensuring the area around the meter is clear with good access¹¹. Appliances left running when the supply drops will simply stop; shutting them down properly avoids problems when power returns.

The Wi-Fi router is part of this. Smart Energy GB states that the router will be turned off during the power cut, but once it is switched back on the smart meter will not impact the Wi-Fi connection⁷. A smart meter does not use your Wi-Fi, does not connect to your router and does not affect broadband speed⁸. Smart meters do not need home Wi-Fi to work, and the in-home display is not connected to the internet, so installation is possible in homes without broadband¹⁶.

Households with specific needs should raise them before the appointment. This is especially important if someone relies on medical equipment powered by electricity; the supplier should explain what will happen, how long the appointment may take and whether the supply needs to be switched off briefly¹⁶. The same applies to anyone who needs advance notice to make arrangements: a 30-minute warning before the installer arrives can be requested¹⁷.

What your installer should tell you on the day

The appointment carries obligations on the supplier's side. Your smart meter should be installed with minimal disruption, key safety checks should be carried out during the appointment, and an in-home display should be offered and demonstrated¹⁰. Installers are expected to provide energy efficiency advice⁴, and some providers may offer a free energy efficiency inspection during installation⁵.

The roll out is led by energy suppliers, so the installer attending is working to the supplier's process rather than a separate body's¹⁸. To arrange a visit, the household contacts its energy supplier, which will say when one can be installed¹⁹. Any household that pays for energy, whether owning or renting, should be able to book an installation where it is expected to work in the property¹⁰.

Unusual circumstances should be flagged in advance. Which? advises telling the energy company when the appointment is made, or at least several days before the installation, about anything unusual in the home or at the meter³. That includes poor mobile signal, which can affect how the meter communicates: in an area with poor signal, a special type of smart meter pre-set with the times for switching between peak and off-peak rates may be needed²⁰.

The installer should also be clear about what happens next. The first bill after installation may still be estimated, and the supplier should be contacted if estimated bills continue beyond that²¹.

Will my gas supply be turned off too?

Yes, briefly. The gas meter is changed during the same visit, and the gas supply is switched off during that changeover, typically for around 30 minutes¹. Which? puts the gas interruption at around an hour³. The two supplies are usually dealt with one after the other rather than at the same time.

There is a wider point about gas and power cuts that is worth separating from the installation itself. If the electricity goes off, gas supplies and meters will usually continue to work normally, but most boilers may not work because they use electricity for pumps, fans and electronic controls²³. So a household with gas heating will lose heating and hot water during the electricity interruption even though the gas itself is still flowing.

Where the gas and electricity are supplied by different companies, Smart Energy GB suggests having the electric smart meter installed before the gas smart meter¹. That sequencing keeps the two appointments from interfering with each other.

Consumer protections apply to both fuels. Households are protected by strict regulations against a supplier switching off or disconnecting gas or electricity supply, and the protection is as strong as with traditional meters²¹. Consumer protections against supply being cut off are the same for smart meters and traditional meters²⁴. Before any remote disconnection, the supplier must have contacted the household to discuss repayment options and visited the home to assess the personal situation²⁵, and must visit to make sure disconnection will not affect the personal situation, for example if someone is disabled or elderly²⁶.

Do I have to accept a smart meter installation?

No. Installation is not compulsory, and a household can refuse if the supplier offers one². The Energy Ombudsman confirms that it is your right to refuse the installation of a smart meter, though replacement options may be limited if a traditional meter is faulty or unsafe¹².

In practice, the choice is narrower than the right suggests. Most energy companies no longer have traditional meters, so if a meter needs replacing, a smart meter is what will be fitted³. Only under exceptional circumstances would a supplier be expected to change a smart meter back to a traditional meter, and the supplier may charge the costs if it agrees¹².

There is a middle option for households that want the meter but not the connectivity. A supplier can be asked to fit a smart meter with its communications switched off, so that it operates as a traditional meter³. That keeps the meter compliant with the supplier's replacement programme while removing the automatic data flow.

For a household weighing energy independence, the trade-off is straightforward. A smart meter with communications enabled gives access to detailed usage data and to time-of-use tariffs, but it also depends on the national communications network and on the supplier. A meter in dumb mode removes that dependence at the cost of the functions that make it smart.

After the install: getting your smart meter working again

The supply comes back when the installer restores it, and the meter should begin operating immediately. The first bill after installation may still be estimated, and the supplier should be contacted if estimated bills continue after that²¹. That is a billing transition rather than a fault with the meter.

If the meter does not operate in smart mode, Ofgem lists three possible causes: it loses connection with the supplier, it loses connection after a supplier change, or it has been installed without being connected to the national communication system²⁷. An older first-generation meter may not be working in smart mode if the supplier was switched following installation²⁸. Most first-generation meters are now connected to the central network and have regained their smart functions¹⁴, and a meter may work in smart mode again if tariffs or suppliers change²⁹.

Switching supplier is not a reason to expect the meter to stop working. Many smart meters retain the ability to send automatic meter readings after a switch³⁰, and with a second-generation meter all smart functions are kept with no interruption¹³.

The dependence that remains after a successful installation is worth stating plainly. The meter needs the national communications network to send readings, and it needs the supplier to act on them. The data it produces puts a household in control of its energy usage and supports energy-saving steps³¹, but the meter itself is not a source of independence from the grid. It is a measuring and communication device, and it works only as long as the network and the supplier relationship behind it do.