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 32 replies
  • Subscribers 33 subscribers
  • Views 4643 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

Lightning electrodes

lyledunn

A relatively small parish church has 8 down conductors connected to rod electrodes. Each electrode measured separately ranged from 215 ohms to 12 ohms with the overall value being around 8 ohms. Now I am aware that the overall value should be less than 10 and that each individual electrode should be no more than 8x10. We have one at 215 and one at 135, the others meeting that requirement. It is easy for me to advise that the system does not meet code but I do not have the expertise to assess the implications of the situation. I would appreciate your opinion. 

Parents
  • 0

    If lightning strikes the rod with a high resistance to earth, then the down lead and anything attached thereto will briefly be at a very high voltage to true earth.

    Anyone touching the down lead would probably be killed.

    The high voltage will force some of the current through the walls and via the foundations to earth. This can dissipate several megawatts as heat in the walls, albeit for a tiny fraction of a second. Any moisture in brick or stone will flash into steam with explosive force, perhaps bringing down the wall.

    Wooden parts such as roof timbers may be ignited. Metal rainwater goods and metallic roofing materials will conduct dangerous voltages to other parts of the building, destroying electrical equipment and perhaps starting fires.

     

Reply
  • 0

    If lightning strikes the rod with a high resistance to earth, then the down lead and anything attached thereto will briefly be at a very high voltage to true earth.

    Anyone touching the down lead would probably be killed.

    The high voltage will force some of the current through the walls and via the foundations to earth. This can dissipate several megawatts as heat in the walls, albeit for a tiny fraction of a second. Any moisture in brick or stone will flash into steam with explosive force, perhaps bringing down the wall.

    Wooden parts such as roof timbers may be ignited. Metal rainwater goods and metallic roofing materials will conduct dangerous voltages to other parts of the building, destroying electrical equipment and perhaps starting fires.

     

Children
No Data

Community Rules & Guidelines