Replacing fuse box with consumer unit

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Replacing Fuse Box With Consumer Unit

If you notice issues with your home electrics, such as the electricity tripping or the fuse blowing, chances are that they are because you are running too many appliances on a fuse box that is not designed to withstand that level of power consumption.

The solution to this problem is to either replace your fuse box or better yet, use this chance to upgrade to a new consumer unit.

Consumer units are much better than fuse boxes and can provide more protection. They can also be used with a smart meter to keep a check on your energy consumption, which is extremely useful in saving electricity as well as money on your energy bills.

Read on to find out more about fuse boxes and consumer units, how consumer units are better, how much it costs and the total time it takes to replace a fuse box with a consumer unit, and much more:


A fuse box and a consumer unit are the same thing and serve the same purpose. Both are main electrical components that control as well as monitor the electricity running through your property.

They ensure that everything is working as it should, and whenever a fault is detected, they “trip” to protect the home electrics and appliances from damage.

The main difference between the two is that fuse boxes are the older and outdated version of consumer boxes. Older fuse boxes generally contain fuses with a wire inside which melts when there is an electrical overload.

Modern consumer units, on the other hand, have built-in circuit breakers which automatically switch off the unit in the event of an overload. They can be reset easily and with no damage when the issue is resolved by manually switching them on.


Consumer units are basically the better, more modern, and safer versions of fuse boxes. In most cases, fuse boxes are no longer compliant with current electrical regulations, and if your property is fitted with one, you need to have it replaced with a consumer unit.

It is very easy to tell if you have an outdated fuse box or a modern consumer unit installed on your property.

An old fuse box will have a fuse carrier with several fuses inside which you can remove and replace manually when one of them goes off in the event of a power overload.

Some fuse boxes may even have wooden racks or cast-iron switches. If that is the case, it usually means that they are very old and date back to before the 1960s.

A consumer unit, on the other hand, is made of horizontal rows of MCBs (Mini Circuit Breakers). Each MCB has a switch that will turn off in case of a power surge.

If you are unsure about whether you have a fuse box or consumer unit, and whether or not it needs to be replaced, you can consult with a specialist for professional recommendations.

Other than being unsafe and non-compliant, old fuse boxes may even become used and worn out over the years. The electrical screws may become loose or the wiring may be affected by wear and tear, which may pose safety hazards and lead to electrical fires.

Upgrading your old fuse box becomes inevitable after a while and needs to be done eventually as old ones may simply stop working due to old age.

If you have an old fuse box, it is best to have it replaced with a new consumer unit for better protection, performance, energy-saving, and compliance.

Contact Calder Electrical services right away and speak to our professionals about your upgrade options.


Before we discuss how much a fuse box replacement costs and how much time it takes to carry out the job, you need to understand what the work actually entails.

Here is a breakdown of what is included in a fuse box replacement:

  • Before the installation work begins, the main electrical power supply is switched off.
  • Next, the current fuse box is disconnected by taking off its lid and unscrewing the fuses.
  • The wires are then unhooked and the fuse box is removed from the wall.
  • After the fuse box is completely removed, the new consumer unit can be attached.
  • The front panel of the consumer unit is removed and the back is screwed to the wall.
  • The main wires are pushed back and connected to the right outlets.
  • The front panel is then screwed in and secured.
  • Once the unit is secure and in place, an initial test using a voltmeter is performed by the electrician in order to check if everything is working fine.
  • Additional circuit tests may also be performed, which are recorded on an Electrical Installation Certificate (EIC), a copy of which is given to the property owner.
  • The work is also logged with the Local Building Control and a confirmation letter is issued from the relevant registered electrical body.


A consumer unit is made up of the following components:

  • The main switch – this is the control for the power coming into your property. You can use it to turn off the mains if you have electrical work going on, and easily turn it back on when you want the power restored.
  • RCD – RCD, short for Residual Current Device, is a group of switches that protect you and your property from the risk of electrocution, such as when you cut a live wire by mistake. It also minimises the risk of fires by immediately cutting off the power supply if it detects a fault.
  • MCB – MCB, short for Miniature Circuit Breakers, are, as the name suggests, small circuit breakers that protect against power overloads and short-circuit issues. If the circuit is overloaded due to too many appliances working at the same time or because of a wiring issue, the circuit breakers will trip and cut off the electricity to your property.
  • SPD – an SPD, short for Surge Protection Device, is a device that protects your home and electronic devices from high-voltage power surges. It is installed only if the electrician feels you need the extra protection.
  • RCBO – the RCBO, short for Residual Current Operated Circuit Breaker, is used in combination with an MCB to protect you and your property from most electrical faults.
  • Timer – while most consumer units do not have timers, you can have one installed by your electrician if the need arises. The purpose of a timer is to allow you to automatically turn certain circuits on and off, which can be extremely useful while you’re away, such as on a holiday. You could also set it to turn on the lights at a specific time, such as when you get home from work.


The total cost of replacing a fuse box with a consumer unit is dependent on many factors such as:

In addition to these, you will also have to factor in the labour cost, materials, and testing. The labour cost will vary depending on whether the charges are on an hourly or daily basis, how long it takes to install the new consumer unit, and the location of the fuse box.

On average, replacing a fuse box with a consumer unit, including all the materials, labour costs, and certification, will cost between £375 and £550. This is a general figure that assumes an ideal scenario with no additional problems.

Let’s look at each factor in detail:


One of the main determining factors of the cost of a fuse box replacement is the type of consumer unit itself. There are several types of consumer units and each has a different effect on the total cost of the job:

Fully Loaded Consumer Unit

A fully loaded consumer unit combines both the input and output breakers in one fuse switch and is categorised by its two sets of RCDs and MCBs.

It costs around £60 to £120 and is an ideal solution for those who don’t require circuit separation.

Split-Load Consumer Unit

A split-load consumer unit features a main switch and an RCD. It can easily be identified by the position of the MCBs, which is located on the side of the RCD, while the RCBO is usually placed beside the main switch.

These units separate the large appliances from the rest of the house, for example, the oven, which is a heavy appliance, may go through a separate RCBO and have its own RCB and MCB, whereas the rest of the electrics will run through MCBs connected to a single RCB.

The cost for split-load consumer units ranges between £80 and £125.

Garage Consumer Unit

A garage consumer unit is a smaller version of a full consumer unit and can cost around £25 to £60. With 2 to 5 fuses to handle power needs and issues, it is made specifically for garages and other exterior buildings such as sheds and extensions.

An accompaniment to the traditional consumer unit, garage consumer units come with a range of features designed specifically to ensure that your property remains protected at all times.

RCD Dual-Split Consumer Unit

An RCD dual-split consumer unit has multiple sets of circuits that allow separately powering the electrics in a single property. For example, if your home has 2 floors, you can use an RCD dual-split consumer unit to divide the two areas and power them individually.

They cost around £40 to £130 and are very useful for times when you don’t want all the home electrics to be shut off at once.

High-Integrity Consumer Unit

High-integrity consumer units are designed to have separated circuit boards for standard and critical loads, meaning that your lighting will stay on in case there is a fault on one circuit board. The MCBs and RCBOs make sure that the other circuits aren’t impacted by the fault.

The average cost of a high-integrity consumer unit is around £50 to £150.


The size of your home is also another important factor to consider as it determines how many circuits and amperage you’ll need. The bigger your property, the more circuits and the higher amperage you’ll require, which of course, will increase the total cost.

Here is a breakdown of the estimated prices of the number of circuits for your consumer unit:

Number of circuitsAverage cost

Here is a breakdown of the estimated prices of the amp rating required for your consumer unit:

Amp ratingAverage cost
40-amp unit (2 modules and 2 to 3 ways)£270 to £300
63-amp unit (1 to 6 ways)£300 to £350
80-amp unit (7 to 10 ways)£390 to £440
100-amp unit (7 to 16 ways)£470 to £510


The health of your existing wiring plays an important part in the total fuse box replacement cost. If the electrician working on your system notices that your property’s electrics are in bad shape, they may recommend getting the place rewired.

Some key signs to look out for that determine if your house needs rewiring include flickering lights, power surges, burning and discolouration, electric shocks, and circuit breakers tripping.

Rewiring is a big project, considering all the rules, regulations, and checks that need to be followed. The cost to rewire your house will depend on its size and geographical location, among other factors.

On average, the cost to rewire a 2-bed flat may range from £2,000 to £3,900. If the job is straightforward, it should take between 3 and 4 days to complete.

The cost to rewire a 2-bed terraced house, including a kitchen and bathroom, may range from £3,000 to £4,800. The job should take between 5 and 8 days to complete.

The bigger the house, the longer it will take the electrician to carry out the rewiring job and the more you’d be expected to pay.

For more information on rewiring and what it entails, read our detailed guide on what is involved in a house rewiring.


An EICR, short for Electrical Installation Condition Report, is carried out by a qualified electrician and gives you an in-depth analysis of your property’s electrical system.

It identifies any damage, defect, or deterioration that may turn into a potential hazard, along with recording several observations in line with BS 7671 and providing recommendations for improving the installation.

The EICR classifies the condition of the installation into three codes: Code C1, Code C2, and Code C3, with C1 indicating the highest and C3 indicating the lowest level of danger.

The cost of an EICR will fall between £120 and £350 based on the size of your property.

It is recommended in the wiring regulations BS 7671 that a domestic property must be regularly inspected and tested after an electrical installation every 5 to 10 years, or if you are buying/selling the property.

For landlords, a Landlords Safety Certificate, which provides an electrical installation condition report to identify any issues and to make sure the property is safe for use and up to electrical standards and regulations, must be carried out every 5 years or whenever there is a change in occupancy.


Similar to the cost, the total time it takes to upgrade an old fuse box with a new consumer unit is dependent on a lot of things. Generally, the larger the unit, the longer it takes to install it.

The size of the unit is based on the size of your property. A 1-bedroom flat would require a 6-circuit unit and take around 4 to 5 hours to install. A 10-circuit consumer unit may require 5 to 6 hours. 3-bedroom homes tend to use larger 12-circuit consumer units and take around 6 to 7 hours to install.

You may also have to keep in mind any additional work, such as rewiring, which may take around 4 to 9 days to complete depending on the size of the house.


We, at Calder Electrical Services, have been undertaking electrical work since 1976 and have plenty of experience in the field.

We offer a wide range of services to meet the demands of our clients that include all aspects of domestic, commercial and industrial installations, inspections, maintenance, and upgrades.

We have experienced and fully qualified electrical engineers on hand to deliver a professional and high-quality service that is fully insured and certified.

Our team of professionals can survey your house and assess the existing installations to advise on the best way to increase their use and safety.

Contact us here or call us on 0800 612 3001 for more information on replacing your fuse box with a new consumer unit!

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