Domestic Surge Protection – What is it? Types, how it’s used?

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Domestic Surge Protection

Electricity and electric wiring and installations are a huge part of our day to day lives. In fact, it is now impossible to imagine life without them.

We, as a society, are heavily dependent on the continuous and efficient running of these systems as they are what run our homes, offices, shopping centres, banks, factories, and more.

To make sure your electrical systems remain safe and properly functioning, you need to take a few steps, one of them being surge protection.

Power surges can cause considerable damage to your electrical installations and the devices connected to the outlets. In order to minimise the risk and damage, you must add surge protectors in your home so that your devices and installations remain protected against sudden spikes in the electrical voltage.

Read on to find out more about domestic surge protection, what it is, how it is used, its different types, and much more:


A power surge refers to a spike in the voltage coming into your home that results in an increase in the voltage above the designated flow of electricity.

It can be caused by several reasons such as lightning strikes, utility power providers, and turning off and on the electrical cords within your home.

One very common way that a power surge can enter your home is via the landline phone or the coaxial cable connected to your television or computer.

Depending on what is causing the surge, the spike can affect the flow of electricity by as little as 5 volts to as high as 1000s of volts.

Although it may, at times, seem like a harmless flicker or dimming of the lights, a power surge can cause permanent damage to the electronic equipment and appliances in your home, such as:

It has the potential to damage anything plugged into the power outlets or phone landline, which is why it is best to protect your home and all its electric installations and machinery with surge protection.


Domestic surge protection refers to a solution for protecting the electronics in your home against power spikes and creating a safe environment that minimises the risk of electric shocks, burns, and fires.

It includes a small appliance or device, known as a surge protector, that serves two main functions. The first function is to allow you to use a single power outlet to plug in multiple components. The second, more important one, is to protect your home and electronic devices from high-voltage power surges.


A typical surge protection device passes the electrical current along the outlets to a number of devices plugged into them. In case the incoming voltage rises above the acceptable level, it diverts the extra electricity into the grounding wire of the outlets.

Grounding wires run parallel to the hot and neutral wires and provide a pathway for the electrical current to flow in case there is a breakdown in the two wires that normally carry the current.

There are different surge protection devices based on their application and use. Domestic surge protection devices are suitable for light applications and can be fitted into the property’s consumer units and control panels. They provide peace of mind and help mitigate safety hazards associated with power spikes and surges.

Commercial surge protection devices are suitable for offices and other commercial applications and are typically installed in building management systems which include systems and equipment such as computers, security systems, data centres, lifts, and various other electronic and control systems.

Industrial surge protection devices are similar to their commercial counterparts and are designed to protect machinery, devices, and equipment such as circuits and control systems.


The current wiring regulations BS 7671:2018 apply to all kinds of properties including domestic, commercial, and industrial, and state that, unless a risk assessment is carried out, protection must be provided against transient overvoltage which could lead to:

  • Serious injuries or loss of human life,
  • Interruption of public services or damage to cultural heritage,
  • Interruption of commercial or industrial activity,
  • A large number of co-located individuals being affected.

In the previous edition of the wiring regulations, some domestic dwellings were excluded from surge protection requirements if, for instance, they were supplied with an underground cable.

This, however, has now been removed and surge protection is a requirement for all types of premises, including single dwelling units, and applies to all new builds as well as properties being rewired.

Since surges can happen at any time, it is best to make use of surge protection devices to keep your electronic installations and appliances safe from damages.

You may not need surge protection for everything, such as your desk lamps, but you will need it for electronic devices and appliances with delicate microprocessors such as your television, laptop, and refrigerators. You must always plug them into a surge protector instead of directly into the wall socket.

As a rule of thumb, if it is electric and expensive, you must protect it with a surge protector. Keep in mind, though, that power surges won’t necessarily destroy your electronic equipment instantly. More plausibly, it will be multiple surges over time that will cause cumulative damage.


Power surges can happen anytime and can often go unnoticed, especially if they happen while you’re asleep or not at home. Most of the time they are only noticed by their effects and when the damage has already been done.

If a surge of electricity passes through the outlet, it can damage the items that are plugged in and may cause permanent damage.

To prevent that from happening, surge protection devices are used to stop the increased power to flow through your plugged-in machinery and appliances and absorb it instead.

One of the main reasons that domestic surge protectors are so important is because they can protect your electronic devices including anything plugged into an outlet, such as the television, computers, tablets, and kitchen appliances.

Surge protectors can also protect your entire electrical system from damaging power surges, but for that, you will need a whole home surge protector that can cover the entire property.

They protect your entire electrical system, as opposed to outlet surge protectors that only protect the items plugged into them.

Unexpected power surges can be extremely damaging to your electrical system and can affect your fuses and circuits. A surge protector has the ability to absorb the initial volt of electricity, preventing damage to your home’s electrical system and the attached appliances.

There are suitable surge protection options for all kinds of properties and electric requirements, available at varying complexity levels and prices.

In addition to prolonging the life of your electronic devices and appliances, surge protectors can prevent the need for costly repairs. The damages oftentimes can be serious and may render the devices completely inoperable, resulting in the need for expensive repairs and replacements.

Surge protectors make a worthwhile investment, especially if you consider how they can save you hundreds and thousands in damages in your home.


There are 3 types of surge protection devices (SPDs) most commonly used depending on where they are installed. They are:

Type 1 Surge Protection Devices

Type 1 SPDs are capable of discharging a partial lightning current with a waveform of 10/350µs and are used at the origin, i.e., the main distribution board.

They are recommended in the service sector and industrial buildings and typically use a spark gap to redirect the excess voltage to earth and prevent it from reaching your property.

Type 2 Surge Protection Devices

Type 2 SPDs are installed at the sub-distribution boards and are intended to protect equipment attached to an installation.

They more commonly use a metal oxide varistor (MOV) to direct the current away. Combined SPDs (type 1 and type 2) are also available and are usually installed in consumer units.

Type 3 Surge Protection Devices

Type 3 SPDs provide local protection for sensitive equipment such as televisions and computers and are much smaller scale as compared to the other types.

Since they have a relatively low charge capacity, they must only be installed as a supplement to type 2 SPDs.


Choosing the correct domestic surge protection depends on a variety of factors such as:

  • The exposure of your home to lightning transients
  • The sensitivity of your electronic equipment requiring protection
  • The location of the equipment
  • The exposure level of the installation

With such a wide variety of surge protectors available in the market, it can be difficult to find the right one for your needs at a good value. There are certain features that all good surge protectors share and you must keep them in mind when getting one. They include:

Joule Rating

Joules are the standard unit for measuring the energy released over a period of time. A surge protector’s joule rating indicates the maximum amount of energy the device can absorb.

If the power surge exceeds the limit, it renders the surge protector useless. The higher the joule rating, the more power it can absorb. Therefore, the more joules, the better.

Keeping that in mind, you need to decide how much surge protection you need based on certain things such as the value of the equipment being protected against power surges and the number of devices that require protection.

Usually, 1000 joules will be enough for smaller electronics whereas 2000 to 3000 joules should be sufficient for appliances such as televisions, computers, and washers.

Indicator Lights

Depending on how hard they work, even when a surge protector diverts excess voltage, it can suffer damages while doing so and has a limited lifespan.

That being said, an indicator light is an extremely useful feature since it tells you whether or not the surge protector is working fine. If the indicator light is not working, it probably means that the surge protector isn’t working either and it is time to either get it repaired or buy a new one.

Clamping Voltage

The clamping voltage refers to the measurement that alerts the surge protector to start redirecting the excess voltage away from your home and the plugged-in devices.

A surge protector with a lower clamping voltage will trigger earlier and protect your devices much quicker. For home use, a surge protector with a clamping voltage below 400 volts should be ideal.

Response Time

The response time of the surge protector refers to the time it takes for the device to detect a power surge. A lower response time equals a faster response and a higher response time equals a slower one.

A quick response time reduces the time your plugged-in devices and appliances are exposed to the surge, providing much better protection. Ideally, you should opt for a surge protector with a response time of 1 nanosecond or less.

UL Rating

All good surge protectors come with a UL rating, which is a rating put out by the independent Underwriters Laboratories, that tests the safety of the devices.

If the surge protector doesn’t have a UL rating, don’t bother buying it. In addition to a UL rating, make sure it is a transient voltage surge suppressor since many UL-rated power strips don’t offer surge protection.


Once you have chosen the right type of surge protectors, you need to move on to installing them. Surge protectors (type 1 and type 2) must be fitted at the origin of the supply to the property and can be installed in an existing consumer unit if there is enough space available, or in an external enclosure adjacent to it.

The combined length of the conductors in relation to the current path should not be less than 0.5 metres and must not exceed 1 metre.

For type 3 protection, which is used for sensitive devices, it should be installed close to the equipment it is protecting to further remove smaller transients.

When choosing which devices to protect and the level of protection required, it may also be useful to check with your insurance company since some policies may require the equipment to be protected with a surge protection device to be included in case of a claim.


We have been providing electrical services to residential, commercial, and industrial properties for over 40 years and are specialists in all aspects of electrical installations, maintenance, and testing.

We have experienced, fully qualified, NICEIC registered electrical engineers on hand to deliver a professional and high-quality service following the current wiring regulations.

If you have unplanned issues within your home or business, we can provide a call out service to rectify and solve any problems – ranging from circuits tripping, loss of power, broken items that need repairing, distribution board and consumer unit upgrades, to surge protection installation services, and much more.

Our team can generate a Visual Inspection Report (VIR) to identify anything visual that does not comply with the standards or looks unsafe, as well as a full Electrical Installation Condition Report (EICR) where we identify and test each circuit to make sure they are not deteriorating and are safe for use within the current standards and regulations set by the BS 7671.

We also provide PAT testing of appliances to make sure that any items such as kettles, computers, and microwaves are safe for use in the home and workplace.

Contact us here or call us on 0800 612 3001 to talk to our certified team of electricians to protect your electronic systems and equipment from power surges right away!

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