Intended departures from BS 7671
The word ‘departure’, in the context of BS 7671, is often seen as a dirty word. Nobody likes to declare that their work doesn’t conform to BS 7671. This article looks at when declaring an intended departure may be necessary.
What is an intended departure from BS 7671?
An intended departure occurs when, for various reasons, the designer or installer deliberately chooses not to comply with certain regulations. This differs from an unintentional non-compliance with BS 7671, where the requirements are negligently not met by the designer, installer or inspector.
Regulation 120.3 of BS 7671:2018+A2:2022+A3:2024 states:
“Any intended departure from these Parts requires special consideration by the designer of the installation and shall be recorded on the appropriate electrical certification specified in Part 6. The resulting degree of safety of the installation shall be not less than that obtained by compliance with the Regulations.”
This requirement permits the designer to declare intended departures from BS 7671. The decision to declare an intended departure should not be taken lightly; it is important that the designer ensures the resulting degree of safety of the installation is not less than that obtained by compliance with BS 7671.
How can I confirm the same degree of safety?
Confirming the resulting degree of safety may be subjective and will depend on the intended departure. It is not a case of stating it is no less safe; this must be demonstrable.
In the event something goes wrong, evidence justifying the intended departure is likely to be requested by those investigating the incident. Where applicable, evidence provided by manufacturers of electrical equipment shall be obtained and appended to the electrical certification.
What if I install electrical equipment that does not conform to appropriate British or harmonized standards?
Regulation 133.1.1 of BS 7671:2018+A2:2022+A3:2024 requires every item of electrical equipment to conform to an appropriate British or harmonized standard.
Where no such standard exists, an appropriate international (IEC) standard, or appropriate standard of another country, can be cited.
Regulation 133.1.3 of BS 7671:2018+A2:2022+A3:2024 states:
“Where equipment to be used is not in accordance with Regulation 133.1.1 or is used outside the scope of its standard, the designer or other person responsible for specifying the installation shall confirm that the equipment provides at least the same degree of safety as that afforded by compliance with the Regulations. Such use shall be recorded on the appropriate electrical certification specified in Part 6.”
In some cases, electrical equipment might be manufactured outside the UK and Europe. This does not necessarily mean it is not safe. However, it is the duty of the designer to declare it is no less safe than equivalent equipment that meets the national standards.
An example of an intended departure where no British or harmonized standards exist is for cables such as YY, SY, CY, and newly innovated cables such as power cables incorporating communication cables for electric vehicles (EVs) and photovoltaic (PV) systems.
These cables comply with certain British standards in part, such as for cross-sectional area and insulation. However, no constructional standards exist for such cables, which is why they are not listed in Appendix 1 of BS 7671:2018+A2:2022+A3:2024.
If the cables are third party approved by recognized test centres, such as BASEC, the designer could use it to support a claim if it has the same degree of safety.
Regulation 133.1.2 states: “where there are no applicable standards, the item of equipment concerned shall be selected by special agreement between the person specifying the installation and the installer.”
This would be a matter of a discussion with the client and other interested parties, and documenting the agreement and appending it to the electrical certification.
It is important to note the approach taken by the harmonized documents (HD) that forms the basis for BS 7671 in implementing the underlying technical intent.
Specifically, HD 60364-5-51:2009, Regulation 511.2, sets out requirements for manufacturer declarations in cases where no applicable standards exist for a particular item of equipment (for example, newly developed products). The regulation states:
“Where there are no applicable standards for the item of equipment concerned, the manufacturer shall provide the person specifying the installation or the installer with complete documentation and the necessary test reports, in accordance with the relevant legislation.”
A similar principle should be applied within the context of BS 7671. Where no specific standard applies to a particular item of equipment, or electrical equipment does not conform to appropriate British or harmonized standards, the electrical installation designer or installer should obtain comprehensive documentation and any necessary test reports from the manufacturer, in line with applicable legislation.
A key piece of UK legislation in this regard is the Electrical Equipment (Safety) Regulations 2016, which outlines the technical documentation required to demonstrate a product’s conformity with safety requirements. This technical documentation may include, but is not limited to:
- A description of how the product is designed and manufactured
- Evidence demonstrating how the product complies with relevant safety requirements
- The addresses of the manufacturer and any relevant storage facilities
- A Declaration of Conformity, which must reference applicable designated standards, including their publication dates or relevant technical specifications.
There is also a parallel statutory requirement to conform to the Electromagnetic Compatibility Regulations 2016. The requirement is to prevent interference with radio communication and telecommunications.
By adopting this approach, designers and installers can help ensure that non-standard equipment is assessed appropriately for safety and compliance, aligning with the regulatory intent of both HD 60364 and BS 7671.
What if I install new materials and inventions?
Innovation can lead to products being developed before British or harmonized standards are published. This does not necessarily mean the products are not safe. Manufacturers of such equipment will need to comply with legislation, such as the Electrical Equipment (Safety) Regulations 2016, in order to sell the products.
This legislation requires manufacturers of electrical equipment to design and manufacture with the principal elements of safety objectives, draw up a declaration of conformity and provide conformity assessment marking, such as UKCA or CE. The manufacturer must provide a technical file demonstrating the electrical equipment is safe.
Regulation 133.5 of BS 7671:2018+A2:2022+A3:2024 states:
“Where the use of a new material or invention leads to departures from the Regulations, the resulting degree of safety of the installation shall be not less than that obtained by compliance with the Regulations. Such use shall be recorded on the appropriate electrical certification specified in Part 6.”
The designer must demonstrate that the resulting degree of safety of the installation is no less safe than obtained by conformance to BS 7671. This can be carried out by obtaining the necessary information from the manufacturer for the equipment and appending to the electrical certification. This technical documentation may include, but is not limited to:
- A description of how the product is designed and manufactured
- Evidence demonstrating how the product complies with relevant safety requirements
- The addresses of the manufacturer and any relevant storage facilities
- A Declaration of Conformity, which must reference applicable designated standards, including their publication dates or relevant technical specifications.
What if the intended departure does not relate to electrical equipment?
It could be that the designer decides to choose an alternative design not covered by BS 7671. For example, Regulation 551.7.2 requires the assembly to be rated greater than, or equal to, the combination of the rated current of the incoming overcurrent protective device and the rated output of the generation set, where one is connected to the assembly.
Formula 1
InA ≥ In + Ig(s)
where:
InA is the rated current of the assembly.
In is the rated current or current setting of the incoming circuit overcurrent protective device, either incorporated within the low voltage switchgear and controlgear assembly or upstream of it.
Ig(s) is the rated output current of the generating set or sets.
The designer may decide that because the total possible load current (ITPL) without diversity cannot exceed the rated current of the assembly (InA) in normal service, this provides a resulting degree of safety not less than Regulation 551.7.2.
The designer would need to declare this as an intended departure and ensure the design is no less safe than that obtained by compliance with BS 7671. Schematic drawings can be appended to the electrical certification and used to provide evidence that the rated current of the assembly cannot be exceeded.
How do I record an intended departure on the electrical certification?
There is a section on the electrical installation certificate (EIC) and minor electrical installation works certificate (MEIWC) for declaring any intended departures from BS 7671. There are data entry fields for declaring intended departures for the designer, installer and inspector.
The reason for the separate data entry fields is that it could be that the designer did not intend any departures, but the installer has decided to install equipment that does not conform to any British or harmonized standards. In this case, it is the responsibility of the installer to declare the installation is no less safe and the intended departure.
An example of the format of declaring an intended departure is provided below:
Details of departures from BS 7671:2018+A2:2022+A3:2024
The wiring system used to supply the electric vehicle charging point does not conform to any British or harmonized standards.
A technical file from the manufacture declaring equivalent safety and the declaration of conforming is appended to the EIC.
Figure 1 Electrical installation certificate
When a departure is not a departure
As shown in Formula 1, Regulation 551.7.2 of BS 7671:2018+A2:2022+A3:2024 requires the rated current of assembly to be greater than the rated current of the upstream protective device and the rated current of generating sets.
Some manufacturers provide a declaration that a 16 A PV circuit can be connected to a 100 A consumer unit that is protected by a 100 A overcurrent protective device, providing that the PV circuit is connected to the opposite end of the busbar to the incoming 100 A main switch.
In this case, the manufacturer has declared the rated current of the assembly is 116 A and carried out the necessary verification, such as temperature rise testing, and declared its suitability. This does not need to be declared as an intended departure.
A fault or non-compliance with BS 7671 is never an intended departure. Neither shall it be used to declare for poor design or installation.
Where certain tests are omitted during inspection and testing, this should be recorded as a limitation, not an intended departure.
Summary
It is acceptable to declare intended departures. However, it is important that the resulting degree of safety is not less than afforded by compliance with BS 7671.
Justification and evidence shall be appended to the appropriate electrical certification.
It is important that this information is appended to any electrical certification and is made available for anyone carrying out periodic inspection and testing as required by Regulation 135.1.
Where an intended departure is declared, this must be agreed with all interested parties.
Finally, it is important that the designer and installer are aware that in the event of a problem, they may be required to justify their decision in a court of law.
Acknowledgements
- BEAMA
- Darren Crannis
- Frank Bertie
- Joe Cannon
- John Peckham
- Jon Elliott
- Leon Markwell
- Mark Longley
- Peter Monfort
- Simon Ogborn