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Proposal for Amendment to BS 7671 Regulation 134.1.1

Sergio Fernandez

Regulation to be Amended

134.1.1 (Good workmanship and manufacturer's instructions)
Proposed New Wording

    Good workmanship by one or more skilled or instructed persons and proper materials shall be used in the erection of the electrical installation. The installation of electrical equipment shall take account of relevant manufacturers' instructions as long as they are no less safe than the intent of BS 7671.


Statement of Problem/Reason for Change

    Ambiguity of "Take Account of": The current wording is often interpreted as an absolute requirement to follow Manufacturer’s Instructions (MI), even when those instructions are generic, poorly translated, or based on non-UK earthing arrangements (e.g., ignoring PME risks).

    Safety Hierarchy: Currently, installers face a conflict when an MI contradicts a fundamental safety principle of BS 7671. This proposed wording clarifies that BS 7671 remains the primary safety framework for UK installations.

    Accountability of the Skilled Person: It empowers the "Skilled Person" to exercise professional judgment. If an MI suggests a method that provides a lower level of safety (e.g., regarding RCD selection or earthing), the installer is explicitly authorized to prioritize the higher standard.

Supporting Examples for the "Safety Case"

    EVSE Installations: Where MIs might suggest a lack of RCD protection that contradicts Section 722.

    Terminations: Where MIs for domestic accessories may not account for the thermal effects of high-load continuous use (e.g., EV or Heat Pump circuits).

    Foreign Equipment: Industrial machinery with MIs written for IT or TT systems being installed on a UK TN-C-S system.

As always please be polite and respectful in this purely academic debate.





Come on everybody let’s help inspire the future

  • in reply to alanblaby

    Thus the wording I am suggesting.

    The installation of electrical equipment shall take account of relevant manufacturers' instructions as long as they are no less safe than the intent of BS 7671

  • in reply to GTB

    I agree there is a place for a type AC RCD/RCBO but not in a modern day new install of a domestic dwelling.  The Mi information MAY of been correct at the time it was published in the past but it does not meet the current requirements or is it appropriate for a the current situation when Engineering Judgement is applied.  

    As an example

    A 7kW EV charger or a 10kW shower—suggests a termination method or a protective device that we know will lead to thermal runaway or fails to provide ADS under UK earthing conditions, we shouldn't be forced to 'take account' of it just because it's in a manual. My wording ensures that the Skilled Person is the final safety gate, ensuring the connection to the grid is no less safe than the Brown/Orange book intended

    Does/Could the distinction between "Product Design" and "Installation Erection" help clarify where your proposed 134.1.1 amendment stops and the BS EN standards begin?

    As engineers, we are responsible for the Safety Outcome, not just the Paperwork Trail. If we continue to treat 134.1.1 as a 'blindly follow the manual' rule, we are automating our own obsolescence. Let's empower the 'Skilled Person' to be the guardian of the Safety Intent.

    Come on everybody, let’s help inspire the future.

  • in reply to Sergio Fernandez
    Sergio Fernandez said:
    no less safe than the intent of BS 7671

    As above, this particular terminology would likely not be suitable

  • in reply to gkenyon

    How about ?

    as long as they are no less safe than the current version of BS 7671

  • in reply to Sergio Fernandez

    No, thank you.

    As far as possible, the installer should comply with BS 7671. If the instructions appear to be less safe than BS 7671, that does not mean that BS 7671 may be disregarded. However, having taken account of the instructions, the electrician should use his or her judgement as to how far the instructions should be followed.

  • The conflict between MI and safety that I see all the the is class 2 metallic light fittings that use a silly little plastic terminal box to achieve double insulation. As electricians with UK 3 plate wring we find ourselves forced to get rid of the terminal box, leaving basic insulation exposed and loose cable likely to contact exposed conductive parts if they become loose or damaged. 
    Then some MI go as far as saying this is a class 2 device that must not be connected to earth. BS7671 says that class 2 devices should not be connected to earth. Clearly the device is no longer class 2 but very many electricians don't get this and their responsibility to think through the engineering.

  • in reply to Alan B

     I have connected a cpc to many of these in the past,my view is the manufacturer either does not understand the way we do things here.many seem to think earth or cpc is some type of optional extra.

    I doubt they have heard of ADS,even using there so called double insulated box there will still be single insulated wires in a metal enclosure.

  • in reply to Alan B
    Alan B said:
    2 metallic light fittings that use a silly little plastic terminal box to achieve double insulation. As electricians with UK 3 plate wring we find ourselves forced to get rid of the terminal box, leaving basic insulation exposed and loose cable likely to contact exposed conductive parts if they become loose or damaged. 

    That feels a bit dodgy to me - the electrician would be modifying the original design of the fitting quite significantly - perhaps relying on metalwork and internal mechanical connections to carry earth fault currents it may never have been intended to carry (or no shock protection under fault conditions at all) - not to mention taking on the legal responsibilities of an manufacturer etc. If you can't choose a fitting with appropriate terminals, I'd favour adding an extra joint box or similar and running a single cable from there to the troublesome fitting. (Ones that can fit into the ceiling void through a small hole are available or recessing a small flush box behind wall fittings perhaps).

    As for the metallic fittings that come with no earth terminal and supplied wiring with exposed basic insulation, never mind no means of covering incoming wiring, and no double insulated mark....  

       - Andy. 

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