Consumer Unit Regulations Guide

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Consumer Unit Regulations Guide

There has been a lot of confusion regarding changes to the wiring regulations and how they affect consumer unit regulations

Since the introduction of the 18th edition, there have been some new additions to particular regulations which affect the fitment of consumer units.  AMD2 has also brought a number of differing requirements from the original 18th edition.

AMD2 UPDATES to consumer unit regulations are anything marked in RED

In this blog post we are going to look over these regulations, and see exactly what they mean to you, whether you are installing a new consumer unit or completing an EICR

I’ll try and keep the individual sections short and to the point, however there is quite a lot to fit in here so the whole post is quite long.

It can help to use the contents section, this will break down each part into manageable chunks so you can find exactly which consumer unit regulations apply to the install you are completing/testing.

Consumer Unit Construction

Consumer Unit Regulations Guide 2022 - AMD3 Consumer Unit Construction
Consumer Unit Regulations Guide 2024

Since AMD3 of the 17th edition was introduced in 2015, consumer units in domestic premises have been required to be constructed from a “non-combustible” material.

This generally means that all domestic installations must now have a metal consumer unit installed, unless the consumer unit is installed within a non-combustible enclosure.

Whilst there is no hard and fast requirement to upgrade older installations just because they have a plastic consumer unit, all new installations must now comply with this standard.

EICRs on older installations will come across plastic consumer units quite regularly.  These should only ever be coded as a C3 – IMPROVEMENT RECOMMENDED, there is no requirement in BS7671 to “fail” and thus upgrade these older plastic units

The particular consumer unit regulation relating to this in the 18th edition is 421.1.201

It should be noted that this regulation does not apply to commercial installations, where plastic consumer units can still be installed.

Not only that, but in domestic outbuildings, for example sheds & garages, you can still install plastic consumer units assuming that the outbuilding is not joined to the main building.

The reason these consumer unit regulations were updated is due to the amount of fires which had occurred in plastic boards. This isn’t a true causation though as the only reasons that they would catch on fire is either a fault within or else poor installation practices.

A non combustible consumer unit ensures that any fire is contained within the enclosure itself and cannot spread to the surrounding building materials.

Installing a metal consumer unit on a TT earthing arrangement system was always frowned upon prior to this due to the risk that the enclosure could become live and not disconnect the main OCPD.

This is a conumdrum that needs a whole other guide in itself, and we have done just that! Please check: Can I Fit A Metal Consumer Unit to a TT earthing arrangement system?

Division Of Circuits – RCD or RCBO?

This is a hotly contested debate amongst electricians. Dual RCD & split load boards were popular under previous versions of BS7671. Whilst these never really met the requirements for division of circuits, they were a safe compromise.

It should be recognised though, especially since RCBOs are so plentiful and relatively cheap, that an RCBO board is really the properly compliant with consumer unit regulations, specifically the parts of BS7671 related to dividing circuits to minimise inconvenience in the event of fault.

Consumer Unit Regulations Guide – Division Of Circuits

RCBOs not only minimise inconvenience to the end user, but they allow for much faster fault finding & rectification of issues as it obvious from the get-go which circuit is involved. Dual RCD boards do not allow this, each RCD can cover a multitude of circuits, thus complicating locating faults.

Maximum Leakage Current on RCD / RCBO

The 18th edition of BS7671 brought a new consideration for RCD equipped devices, a ,major change with Reg ????

This states that the maximum leakage current under normal usage must not be more than 33% of the rated tripping current of the device.

For a regular 30mA RCD this basically means that the regular leakage current must not exceed 10mA under normal circumstances.

Whilst this may sound a lot, a modern house with a lot of electrical appliances and gadgets can load up the leakage current under normal use.

In the event of a dual RCD board, where multiple circuits are shared across one single RCD device, this leakage current could easily load up to more than the 33% allowed for the single RCD unit.

RCBO boards, although still covered by the same regulation, are less likely to exceed the 33% limit as they only ever cover one single circuit.

There may still be instances (particularly in the event of IT equipment in offices) where this may be a problem, however this would require circuit design to take this into account, having limited numbers of sockets per circuit or similar.

RCD Type (AC, A or B) – AMD2 UPDATE!

RCD type has been brought into question more with the recent introduction to BS7671 18th Edition Amendment 2.

This section of the consumer unit regulations now require that type AC RCDs can now only be used for fixed equipment with no DC component.

This is now a requirement to use at least type A RCDs (and in some instances, especially for certain types of EV charger installation, type B RCDs) for socket circuit outlets and any fixed equipment which may have a DC component. This covers quite a large range of stuff now that everything has electronics on board.

In a vast majority of cases this will be the end of the type AC RCD as manufacturers look to consolidate onto the type A as a minimum.

Check our full RCD Regulations Guide for more information on this

Surge Protection Devices

Surge Protection Devices have been around for years in specialist situations at risk of damaging computer or other sensitive hardware.

They have been recommended to be fitted in instances where certain risks from surges were present before, however the 18th edition really expanded quite heavily on their use.

In order to determine whether or not to fit surge protection, one can carry out an assessment using a formula laid out in the 18th edition. This is worthy of a post on it’s own, so we won’t go into it too much here.

Consumer Unit Regulations 2024
Surge Protection Devices (SPD)

However, suffice to say that as the demand for them has increased over the introduction of the 18th edition, the cost of these devices has come down, significantly.

A T2 SPD can be had for most brand name domestic boards for £50 or less at the time of writing (Nov 2023). At this cost, together with the advent of LOTS of sensitive equipment such as Tv’s, Computers and digital equipment, fitting one is a no brainer.

Our standard practise is to fit these on all consumer unit installations now. The cost is outweighed by lifespan improvements on sensitive equipment.

Not only surges of atmospheric origin (such as lightning), SPDs can also protect against constant small switching over-voltages from appliances within the premises.

AMD2 UPDATE: The flash map from the original blue book 18th edition has been removed. This has been replaced with a simpler set of instructions relating to fitting SPDs. Basically now, unless the customer is willing to agree in writing to their omission, SPDs should be fitted upon replacement of a consumer unit or new installation.

Check our full SPD Regulations Guide for more information on this

Arc Fault Detection Devices

With AMD2 to the 18th edition being introduced only a couple of weeks from writing (Feb 2022) I’ll leave this section for update, which I’ll do as soon as AMD2 is released properly and we know how it affects consumer unit regulations.

Suffice to say, up to now, Arc Fault Detection Devices (AFDDs) have been expensive and only recommended for certain particular risk areas for arcs

That could be set to become a requirement across a broader spectrum of installations (even regular domestic) after the introduction of AMD2.

Unlike SPDs which only require a single unit per board (or at the incoming of the installation), AFDDs are “per circuit” the same as an RCBO.

Although the cost of these devices is still quite high, it is likely (as was the case with SPDs) that once they become mass produced then the cost will fall

AMD2 Update: Biggest change to the consumer unit regulations 2022 relates to the fitment of Arc Fault Detection Devices (AFDD)

To summarise, they are now a requirement for installations within certain defined risk residential properties (above 6 storeys), care homes, HMOs & a small other number of cases for socket outlets below 32A

Recommendations for their use are given for other circumstances also, however you would need to address these on a case-by-case basis.

Check our full AFDD Regulations Guide for more information on this

Consumer Unit Labelling

There are a number of consumer unit regulations which apply to the labels which need to be applied to the unit itself (or in some instances close by is acceptable, with multiple boards and switchgear cupboards)

The most obvious of these is the labels indicating the purpose of the switchgear. On a simple domestic installation this would be the labels underneath the MCBs/RCBOs. In commercial instances, this could be labelling for overcurrent protective devices on distribution boards, but could also be printed labelling on switched fuse units and similar.

Inspection & Testing Labelling

There must be a label indicating the date of the last inspection & testing completed on the installation. This also must state the recommended date of the next inspection & testing, depending on the type of installation and it’s use, this could be anything from 3 months to 10 years.

In particular for landlords with the new PRS (Private Rental Sector) regulations 2020 which require domestic private landlords to supply a new EICR every 5 years. Owner occupied domestic properties can be recommended to be tested every 10 years if they are particularly new and have no obvious reasons for excess use.

BS7671 Dual Colour Warning Label

18th AMD2 SHOCKER!! Trusty Old BS7671 Dual Colour Warning Label no longer a requirement!!

If the wiring of the installation uses the previous colour insulation at any point, IE: Red & black non-harmonised (pre 2004) colours, then a label warning the use of wiring colours to 2 versions of BS7671 must be fitted to the consumer unit.

There is still a significant amount of this cable installed over the UK and it will be good for many years to come so expect to see these labels on a very high percentage of installations.

Latest AMD2 updates have however, dropped the requirement for BS7671 dual colour warning labels, as many consumers end up removing them from the front of the consumer unit, particularly if the consumer unit is on show within a room as opposed to under the stairs or in the cellar!

RCD Testing Label

If the installation has RCDs fitted in any way, then a label warning to test them must be fitted to the consumer unit. In 18th edition (new) installations then this should be for testing every 6 months, although prior to this the label was for testing every 3 months.

If you are inspecting older installations then the older label is fine without needing swapping as, in a strange (but understandable) relaxing of any consumer unit regulations, the requirements for testing intervals have actually got longer as opposed to more frequent!

Other Labelling

A number of other labelling requirements exist for use in particular circumstances, these including, but not limited to:

  • More than one source of supply (IE: Microgeneration)
  • Circuits with no protective conductor (quite rare now, however some older installations still have no CPC on the lighting circuits)
  • Live parts which cannot be isolated by a single devices – If a single board is attached to 2 supplies (for example dual rate supplies to economy7 customers with a single dual rate board), then this must have a warning label fitted

Despite how innocuous they may seem, labelling in BS7671 is actually more in depth than you would imagine, depending on the particular installation and what the circumstances are. As such, it would be too deep to cover all of them on our consumer unit regulations guide! We’ll write a full BS7671 labelling guide soon and link back to it from here.

AMD2 Update – All requirements for warning notices as above under the other labelling header still exist within AMD2:2022

12 Responses

  1. which regulation bs7671
    mcb/rcbo for domestic conurmer unit that they shall be in assending order from the main switch or protective device or can they be any placement in the unit

    • Hello Stephen

      I’ve heard this mentioned a lot and was taught it myself, but I’ve never seen a regulation which states this? Can you point to one?

      Kind regards

    • Hi Gavin thanks for getting in touch with the question

      Whilst there is no hard and fast regulation, it’s generally accepted industry practice to leave at least 10% spare ways. There are instances where this may not be possible, for example if the space available does not permit a large enough board to be fitted. In these instances there isn’t much you can do, however where there is the room I always tend to leave a couple of spare ways for future additions

      Hope that helps?

      Kind regards

  2. Hi, we have a domestic property with the consumer unit located in the attached garage. There is another domestic property above the garage. Are we OK keeping the consumer unit where it is?

    Thank you

    • Hello Jones

      Thanks for getting in touch with the question.
      Yes that would be OK to keep in the same position, I assume that there is a fire break (probably plasterboard ceiling) in the garage to make it separate from the property above?
      This is more of a fire/building regulation than an electric one, the consumer unit itself is fine where it is.

      Kind regards
      Electrical Assistance Team

  3. I’m being told there is no requirement for a circuit schedule in domestic properties now, can you confirm, please?

    • Hi Chris, thanks for getting in touch

      With regards consumer unit labelling, in domestic properties, regulation 514.9.1 now contains an exemption for domestic properties which means that circuit schedules are no longer required to be fitted.

      Hope that helps?
      Regards – Electrical Assistance Team

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