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concrete pad anchored 24vDC scissor lift and equipotential bonding

psychicwarrior

Hello good afternoon everyone. I'm after an opinion please on a requirement to bond.

A '4 ton' twin scissor lift platform installation to a concrete pad [set in the ground], for raising vehicles, has 2 seperate ground anchored metal base and framework scissors  and each contains a 24V DC motor.  These scissors are connected to a control unit which draws its supply, from the the 240V AC electrical installation.    Other than the case of the control unit (confirmed as exposed parts), the metal work of the scissors is not electrically earthed (or intended to be) I am informed due to the extra-low voltage motors.

It could be (could it) that once the bases of the scissors are anchored into the concrete pad, especially depending on the anchoring arrangement (depth etc),  that this metal work becomes extraneous part.

The detached garage is supplied from a main building with TN-C-S earthing arrangement  (the garage does not have any other extraneous parts).

Would folk agree that  there is/could be a bonding requirement for the scissor parts  and is there any issue with doing this (if it is extraneous) with the 24V DC arrangements contained ?

Thank you.

Habs

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  • 0

    A piece of lifting equipment like this is likely to be classified as 'machinery' for the purposes of the Supply of Machinery (Safety) Regulations (see guidance on the Lifting Operations and Lifting Equipment Regulations on the HSE web-site: https://www.hse.gov.uk/work-equipment-machinery/loler.htm)

    Downstream of the point of connection of the machinery to the mains supply, BS EN 60204-1 applies to machinery, and NOT BS 7671. (The electrical equipment of machines covered by BS EN 60204-1 is specifically excluded from the scope of BS 7671.)

    In certain situations, BS EN 60204-1 has very different requirements for earthing and bonding to BS 7671. If there is any doubt about installation requirements such as earthing and bonding, it would be advisable to seek guidance from the manufacturer, not least because of potential safety issues with controls and electromagnetic compatibility.

    If memory serves, the manufacturer of the machinery is required to address this kind of thing in their instructions, according to BS EN 60204-1.

    The manufacturer may also require, or recommend, that certain electrical tests are conducted in accordance with BS EN 60204-1, which may differ from those carried out in BS 7671.

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  • 0

    A piece of lifting equipment like this is likely to be classified as 'machinery' for the purposes of the Supply of Machinery (Safety) Regulations (see guidance on the Lifting Operations and Lifting Equipment Regulations on the HSE web-site: https://www.hse.gov.uk/work-equipment-machinery/loler.htm)

    Downstream of the point of connection of the machinery to the mains supply, BS EN 60204-1 applies to machinery, and NOT BS 7671. (The electrical equipment of machines covered by BS EN 60204-1 is specifically excluded from the scope of BS 7671.)

    In certain situations, BS EN 60204-1 has very different requirements for earthing and bonding to BS 7671. If there is any doubt about installation requirements such as earthing and bonding, it would be advisable to seek guidance from the manufacturer, not least because of potential safety issues with controls and electromagnetic compatibility.

    If memory serves, the manufacturer of the machinery is required to address this kind of thing in their instructions, according to BS EN 60204-1.

    The manufacturer may also require, or recommend, that certain electrical tests are conducted in accordance with BS EN 60204-1, which may differ from those carried out in BS 7671.

Children
  • 0 in reply to gkenyon

    good points.   in fact the  manufacturer (which offer an installed or self install package - this setup runs off a 13A socket they said) was contacted and they said they were not aware of any installation that has ever been bonded  as an extraneous part .    it will be interesting to see how earthy the lift part ends up once anchored into the concrete.  :-)

  • 0 in reply to psychicwarrior

    In that case, there are two options to comply with BS 7671:

    (a) Ensure the extraneous-conductive-parts are kept out of arm's reach of any exposed-conductive-parts and other conductive metalwork in the building; or

    (b) Get in contact with the manufacturer and ask them what to do because the UK national wiring code (BS 7671) requires main protective bonding to be applied in this situation to prevent electric shock due to simultaneous contact with either exposed-conductive-parts or other extraneous-conductive-parts within the installation.

    Is this a commercial installation in the UK, that you've been asked to look at a new installation for? If so, the Client also has duties under CDM to resolve this issue, say if it involves other works, or an existing installation . If it's a domestic Client, the Principal Contractor for the works in question undertakes the Client's Duties, and would have to resolve the issue.

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