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 17 replies
  • Subscribers 32 subscribers
  • Views 2514 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

Cross sectional area of a protective conductors

MS01
Can someone give me a some advice on if we have a earth electrode system made up of the structural rebar when using the adiabatic equation to size of the bonding conductor comes out at 300mm. MY questions is does each bond need to be this size or can it be made up via a series of smaller bonds that are equal or exceed the 300mm requirement? My opinion is each bond needs to be this size to deal with the fault current as the direction it will flow is unknown. What are peoples thoughts? I cannot see anything in the regs on this.

Parents
  • 0
    MS01:
    The fault current for the project is abnormally large exceeding 90kA hence the protective bonding conductor size, note the earthing is part of a global earthing system.  

    400V / 5MVA supply. The impedance of the electrode system is 1.369 ohms

     


    If it's a normal 400/230V system (so 230V to Earth) and the electrode has a resistance of 1.369 Ω then, by Ohm's Law, I don't see how more than 168A can flow through the conductors to your electrodes.


    OK it might be wise to leave a generous margin in case the electrodes have a lower resistance after some wet weather, but even so a 4mm² might be adequate.


       - Andy.


Reply
  • 0
    MS01:
    The fault current for the project is abnormally large exceeding 90kA hence the protective bonding conductor size, note the earthing is part of a global earthing system.  

    400V / 5MVA supply. The impedance of the electrode system is 1.369 ohms

     


    If it's a normal 400/230V system (so 230V to Earth) and the electrode has a resistance of 1.369 Ω then, by Ohm's Law, I don't see how more than 168A can flow through the conductors to your electrodes.


    OK it might be wise to leave a generous margin in case the electrodes have a lower resistance after some wet weather, but even so a 4mm² might be adequate.


       - Andy.


Children
No Data

Community Rules & Guidelines