Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 9 replies
  • Subscribers 38 subscribers
  • Views 1348 views
  • Users 0 members are here
Options
You may also be interested in
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

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

Parents
  • 0

    Bonding of extraneous-conductive-parts is only required if the method of protecting from electric shock is ADS (although bonding still might be a good idea if extraneous-conductive-parts might import a non-Earth potential from other installations, but that's unlikely to be the case here).

    So ignoring the 24V (presumably SELV) motors, the question then becomes are these parts you want to bond within reach of anything that's subject to ADS?

    Then there's the question of whether the concrete pads are sufficiently well connected to true Earth potential - if inside a building and above the damp proof membrane, they may well not be. A test of the part to something well connected to Earth (say the supply PE) and see if their resistance to Earth is less than say 23kΩ would be a first step there.

       - Andy.

Reply
  • 0

    Bonding of extraneous-conductive-parts is only required if the method of protecting from electric shock is ADS (although bonding still might be a good idea if extraneous-conductive-parts might import a non-Earth potential from other installations, but that's unlikely to be the case here).

    So ignoring the 24V (presumably SELV) motors, the question then becomes are these parts you want to bond within reach of anything that's subject to ADS?

    Then there's the question of whether the concrete pads are sufficiently well connected to true Earth potential - if inside a building and above the damp proof membrane, they may well not be. A test of the part to something well connected to Earth (say the supply PE) and see if their resistance to Earth is less than say 23kΩ would be a first step there.

       - Andy.

Children
No Data

Community Rules & Guidelines