18th Edition Consumer Unit Requirements – A Complete Guide [2024]

When changing rules and regulations create quite confusion among people. One particular regulation that has confused people is the 18th edition consumer requirements.

Since the introduction of BS 7671:2018, there have been quite several key additions to the 18th edition wiring regulations that may or may not greatly affect the fitment of consumer units.

To shed light on this matter, we’ll look at some of these changes and if they can affect you, whether you are completing an EICR or installing a new consumer unit.

18th Edition Consumer Unit Wiring Regulations

There may be a lot of confusion about the changes in the wiring regulations and the effects of consumer unit regulations.

The 18th Edition Wiring Regulations, or the BS 7671 or IET Wiring Regulations, is the British Standard for electrical installation.

It is a guideline set by IET or the Institute of Engineering and Technology regulation group that covers the installation of new and existing wirings, including any alterations and additions.

The first edition was published in 1882. However, the previous versions were replaced with a new chapter for electrical installation requirements issued on the 28th of March 2022 and may be implemented immediately.

It’s when the regulations apply to designs, verification, and rising of new installations, even the additions or changes to the existing installation regulation.

To know more about wiring, check out the different wiring types codes here!

RCD Protection

What is RCD? It stands for the Residual Current Device known for being sensitive as it switches off electricity in 10-50 milliseconds, especially if there’s an electrical fault.

Not only does it work as one of the protective devices in preventing any serious injury, but it’s also designed to protect human life as it prevents electric shock and fire due to earth faults.

According to regulation 531.3.3, various types of RCD exist; A, B, AC, and F.

The amount of equipment that we link to our electrical installations and systems may impose direct current wiring systems, components, and frequencies onto the existing circuits and lighting circuits.

However, it reduces the effectiveness of the RCD-type operation. The regulation states that only Type A RCDs can be used for general purposes.

On the other hand, Type AC RCDs can only be used for fixed equipment if the Type AC RCD load does not contain DC components.

Nevertheless, this reduces the effects of unwanted tripping that may result in a potential catastrophe.

RCD Protection for Socket Outlets

There is already a new edition or additional requirement for the 30mA socket outlets. It includes the 32A, of which this regulation only applies to sockets up to 20A.

The requirement for the RCD protection level for outlets can only be used to supply the portable outdoor equipment to remain unchanged.

For commercial or industrial activity, monitor if you have socket outlets or existing installations near doors or windows. Always ensure that the existing installations have additional protection.

The same goes for industrial businesses; you’ll likely have outlets with higher RCD protection.

However, it would be recorded as the C2 fault if it’s not yet installed. But it varies on the socket’s location.

For electronic equipment with a limited short-circuit current, automatic disconnection is not feasible.

Before inspecting EICR, we highly suggest you review the RCD or overcurrent protective devices.

RCD Protection for the Domestic Lights

Another regulation specifies an added protection from the 30mA RCD is already required for the circuits in the domestic properties, without any exception.

Note that this domestic installations regulation for other circuits is for domestic places only. As for the landlords, this new regulation applies to the properties, so you will take action to address this.

However, businesses or industrial plants must know that they are not included in this new regulation.

Escape Routes and Wiring Regulations Support

The former regulation about electrical installations of the wiring system should be supported so that they will no longer be accountable for premature collapse, especially when a fire occurs.

The wiring regulations previously required the cables and wiring systems in the escape routes to use the metal fixings. This method is done to avoid premature collapse in any fire that could affect rescue attempts.

Devices for Protection Against Transient Overvoltage

The new regulations about transient overvoltages or atmospheric origin protection should provide the consequence caused by the effects of overvoltages on existing installations.

These electrical installations may not only result in damaging electrical appliances, but also serious injuries, or even loss of life.

Another would be interrupting public services or damaging the cultural heritage. Even more, it may even affect industrial or commercial activity.

With that, the supply line also requires the installation of SPDs for businesses or public services.

Or if businesses think that it’s no longer needed, they will require the documented risk assessment as proof of why the surge protection devices have not been installed.

Electric Vehicle Charging Installations

Section 722, electric vehicle charging, this new appendix, stipulates that any earthing facility should not use one earth electrode for their charging points.

Instead, a separate earth electrode must be installed when using a PME supply.

However, there are several application methods wherein you will still be applicable when complying with the 18th edition wiring regulations.

  • Option 1: Fitting an EV charger with built-in fault protection
  • Option 2: Fitting an EV charger without fault protection but installing a PEN Fault detection device.
  • Option 1 and 2: Your property should have an open-circuit fault provided by the Distribution network operator. This device will work after 5 seconds, reducing the risk of electric shock caused by a faulty charge.

Onshore Units of Electrical Shore Connections for Inland Navigation Vessels

Section 730 requires underground cables will be provided with an additional layer of mechanical protection and be buried at enough depth to avoid being damaged, like the movement of vessels.

This section is dedicated to all onshore installations supplying inland navigation vessels for administrative and commercial purposes.

Labelling Requirements

Several regulations apply to certain circumstances; these include but aren’t limited to the following:

  • Circuits with no protective conductor
  • Two or more sources of supply
  • Live parts which can’t be isolated with a single device

Inspection & Testing Labelling

A label should indicate the unit’s last inspection and installation date.

In addition, it is also recommended that the label should also consist of the next inspection and testing date, which highly depends on the type of installation and its use.

The timeframe is usually around 3 months to 10 years. On the other hand, landlords with PRS or private rental sector regulations of 2020 must provide a new EICR every five years.

Domestic premises are often recommended to do the testing every 10 years if there are no signs of excessive use.

Arc Fault Detection Devices

Arc Fault Detection Devices today have been expensive and recommended for risk assessment of areas. With that, it became one of the regulations across a broad classification of installations.

Unlike the SPD, which only requires a single unit, the AFDDs are usually in “per circuit,” like the RCBO. And even if these devices are quite costly, they still became mass local production.

AFFDs are required when using distribution boards in a metal consumer unit in areas where a fire is likely to occur or in premises offering sleeping accommodations, working with combustible materials, and many more.

Surge Protection Devices

Surge protection devices have been around longer than we know them. They are these types of devices that protect your computer and other sensitive hardware from being damaged.

But for an individual to know whether or not to fit surge protection, they must calculate using the formula used in the 18th edition for further assessment and evaluation.

Prices have decreased significantly, thanks to the high demand for surge protection devices.

As the price of these devices continues to plummet, fitting in one of these is a no-brainer, as your house is mostly installed with sensitive electronic equipment.

Transient Overvoltage Explained

In chapter 44, regulation 443.4.1 and 443.4.2 of the 18th edition wiring regulations, this amendment protects electrical installations against transient overvoltages.

The AQ criteria, whether protection against a transient overvoltage, is no longer stipulated in BS 7671. However, it has to be provided when it can result in to:

  • results in injuries or human life
  • greatly affects a large number of co-located individuals
  • results in an interruption or damage to and of cultural heritage and public services
  • results in the interruption of industrial and commercial activity

For many other cases, a risk assessment is often conducted on whether or not protection against transient overvoltage is required.

AC Final Circuits Explained

Regulation 421.1.7 has been reworked. This regulation now states that Arc Fault Detection Devices must be installed on final circuits when the current supplied doesn’t exceed a rated current of 32A

If you plan on taking the exam, you might want to take a look at the 18th edition mock exam if you want to learn more.

Frequently Asked Questions (FAQs)

You might find some answers below if you have further questions regarding 18th-edition wiring regulations for electrical installations.

Should Plastic Consumer Units Be Replaced?

A plastic consumer unit is no longer highly recommended because it doesn’t meet safety standards.

But most are not required to change existing installations as long as it is well-equipped with updated safety features and is fully wrapped in a non-combustible material.

What Causes Earth Leakage Current?

Leakage current happens when the current finds an alternative path to other neutral and active conductors.

It happens most of the time when there’s an insulation fault in equipment or cables within consumer units during normal operating conditions in different electric equipment like consumer units.


There are plenty of rules and regulations regarding electrical installations, so it is important to comply with them when changing a consumer unit.

These are needed to comply to prevent unwanted catastrophes like fire from happening. It is the sole means of protecting everyone’s safety involving electricity and wired connections.

This article is just a brief overview of the changes made to the 18th wiring regulations. For more information, you may visit the 18th edition courses site to know more!

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