Changing your Consumer Unit or Fuse Board
Protection when you need it the most

Consumer Unit (Fuse Board) Upgrades

If you are reading this, it means you’ve decided it is time to replace your old consumer unit; So what do you need to know about your next steps?

Think of your Consumer Unit as the main hub of your home: it’s the ‘thinking centre’ which controls every electrical aspect of your house. Therefore, it is crucial that you entrust such an important job into the hands of a competent and registered electrician; If the job is carried out incorrectly, you not only risk your home and property being damaged or left in a dangerous condition, but worse still, you are putting the wellbeing of your family at risk.

What you MUST know before replacing your Consumer Unit

It may be time for you to upgrade your old Consumer Unit to the new and improved 17th Edition Consumer Unit if:

  • You are extending your home and need a Consumer Unit which can provide a greater load
  • You are having some other work carried out (kitchen or bathroom replacement) and need to comply with the regulations.
  • Your old Consumer Unit is dated and does not afford necessary (RCD) protection from electric shock.
  • Your wiring installation is dated but you cannot afford a rewire, changing to a 17th Edition Consumer Unit will offer some protection.

In situations where you are undertaking a large building project, it is likely that a builder, or other tradesperson, may have recommended making an upgrade. In any event, whatever your reasons might be, upgrading an old Consumer Unit to one incorporating Residual Current Devices (RCD’s), is a job which many people will now have to consider undertaking at some point.

In your search for someone to carry out your Consumer Unit upgrade, you will be faced with many people who are not qualified electricians, but who will claim to “know all about electrics”. Do not allow yourself to be fooled. Even if they offer to carry out the work for a fraction of the price, it is not just the price that counts; A competent electrician will be fully qualified, Part P compliant, fully insured to do the job, and will offer a lengthy guarantee on the job for years to come.

If the person fitting the Consumer Unit is not qualified, Part P compliant, and is not insured, it really is better to walk away. These people are not interested in your family’s safety or future well-being, they are only interested in your cash!

You should also be wary of anyone who says that you do not need a certificate, or disregards the importance of certification; Not only does your Electrical Installation Certificate (EIC) provide peace of mind for you that that your home is safe, it is also an important document which would be required to assure others of the quality of any works carried out, in the event where you should wish to sell or let your home.

An Electrical Installation Certificate is a legal document, and an electrician is required to carry out mandatory tests on the installation before they can issue a certificate.

So what is the Cost?

When you ask an electrician to quote for a new Consumer Unit, there are a number of things he/she will take into consideration, therefore costs will vary. You should be aware of these factors:

The Materials Involved

Most new Consumer Units come preloaded with Mechanical Circuit Breakers (MCBs), which may or may not be the right rating for your circuits. We, at 123 Electricians will carry out calculations considering the size of the cables, the load and the method of installation to determine the correct size for the MCB’s on each circuit. In addition, we will calculate and replace the meter tails supplying the Consumer Unit from the meter.

Checking Earthing and Bonding arrangements

Before the Consumer Unit is changed, we will check the distributor’s equipment at the origin of the installation (where your meter is) along with the Earthing and Bonding arrangements. This is to ensure that they are properly connected, safe and that they comply with the regulations. This is to ensure your safety.

The time involved for Installation

This will depend on the size of the property, the number of circuits, and the location of the old Consumer Unit. The length of time it will take to strip out the old unit, marking up cables, ensuring they are the right length and in good condition, and then installing the new Consumer Unit, will also need to be taken into consideration.

The time involved in Testing

All of the circuits in the property will have to be tested. There is a series of predefined tests that must be applied to each of the circuits, and the results of this testing form a big part of the certification you will receive.

This is perhaps the most important part of changing a Consumer Unit, however it is often the part that is not carried out correctly, or at all, by those who charge below market value for installing a new Consumer Unit.

Allowance for Fault Finding

We will test all the circuits before work commences to identify any pre-existing faults; We allow for some fault finding because experience tells us that there are often minor issues that need to be resolved. You will be given notice of any major faults, and these will be discussed as a separate job.

The regulations do not require existing circuits to be upgraded to current standards in order for them to be reconnected to a new to the Consumer Unit. However, circuits that would result in immediate or potential danger must be rectified before reconnection.

Again someone who is quoting below market value will not have factored in time for fault finding or testing and this increases the likelihood of one of a few serious risks occurring: The first is that you are likely to be presented with an inflated bill at the end which could be substantially higher than your original quote; alternatively, the ‘fitter’ will ignore the faults in order to make it work so he/she can get paid their original fee, resulting in you being left with a potentially dangerous installation.

Certification and Registration

A change of Consumer Unit is considered to be ‘major’ work, and must meet all of the relevant Standards and Regulations which electricians are required to comply with. In order to comply with this, we will issue an Electrical Installation Certificate for both the Electrical Installation and to confirm compliance with Part “P” of the Building Regulations. We will also notify the local authority that the work has been undertaken. Apart from the fact that doing this properly takes time, it also requires the electrician to be registered with an awarding body such as the NICEIC and all the associated costs that go with that, such as ongoing training and assessments, insurance and membership fees.


Taking all of the above into consideration, you can easily appreciate that there is a big difference between buying an off-the-shelf Consumer Unit, and paying to have a correctly certified, fully guaranteed Consumer Unit, safely installed by a professional electrician.

Most reputable electricians would agree that paying anything below £350 should cause alarm bells to ring, and a good indication that something is being missed: most likely the testing and certification. Being asked to pay more than around £550 for a standard Consumer Unit means that you are probably being over charged, unless there are specific mitigating circumstances.

Residual Current Devices

Under the regulations, where a Consumer Unit is being replaced, additional protection by means of Residual Current Device (RCD) must be provided for:

  • socket-outlets
  • mobile equipment for use outdoors
  • cables concealed in floors, ceilings, walls or partitions
  • low voltage circuits (230v – 240v) serving a location containing a bath or a shower or passing through the zones of those locations

The regulations also state that circuits that are to be provided with RCD protection should be divided between a sufficient number of RCDs, or otherwise designed as necessary to avoid hazards and minimise inconvenience in the event of a fault. In essence this means dividing the home over two or more RCD’s so that if a fault develops you are not left completely without power.

Why is Residual Current Device (RCD) protection so important

Many Consumer Units have Mechanical Circuit Breakers (MCB) that are typically rated between 6amps and 50amps, depending upon what they supply. This is essentially to save the wiring. If a fault develops or there is too much load put on a circuit, the current in the cable may become too high, causing the cable to heat up, melt or even catch fire. The MCB detects the rising current and cuts the circuit off at the prescribed limit therefore preventing damage, though it will not prevent the possibility of receiving an electric shock.

This is why you need an RCD, which is a device which monitors the amount of current flowing out of the live and returning back via the neutral. Under normal condition they will be equally balanced, so it follows that, if there is less current coming back than going out, it must be taking an alternative path. This is what occurs when a Human Being receives an electric shock, the electricity takes a path through the Human Body. An RCD will detect this, and will respond by causing it to trip, disconnecting the electric supply. This is incredibly important; It only takes 0.05amps to kill a Human Being. Where as an MCB would only trip when it has reached it capacity, between 6amps and 50amps, way past the lethal level, an RCD will trip at 30mA, and will save life.

This is why Residual Current Devices are so important; they protect your family and loved ones from coming to, potentially fatal, harm.

The only question left to ask is, why should you use 123 Electricians? Well, the answer is simple; We care about our reputation, and most importantly, we care about your safety.