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 3 replies
  • Subscribers 32 subscribers
  • Views 454 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

Extend TT to out building or separate TT ?

aligarjon
Hi guys.  I Have to take a sub-main to a large external outbuilding.  It is basically a domestic garage but larger than some houses that i have wired not that size matters.


The existing house has a TT earth.  The garage is a good 30 meters away.   Can anyone see a problem with me installing a second spike at the garage and linking it to the house earth as well as a belt and braces type thing or would it be better to keep them separate ?  ( I don't anticipate there being any particular problem with getting a decent Ra at either end)



Gary
  • 0
    Hi Gary

    You can link them without problems, and two never hurt! A TT Earth system can be as large as you like, think of a farm with several buildings with steelwork into the ground and grids in the floors. It just makes it work better if anything as the Re is lower so the voltage during faults is a bit lower.


    David
  • 0
    There's unlikely to be a need for an additional electrode ... but there's no problem installing one if you have the spare money.


    It's just something additional to test later.


    Don't forget that the earth electrode would be earthing for the house as well as the garage, so if by a strange quirk of fortune you have exceedingly low earth electrode resistances in the area, the csa of the cpc to the garage might have to be sized based on the largest let-through energy for a fault to earth in the house - more of an issue of course if you are using overcurrent protective devices for ADS in a TT system, which is very rare.
  • 0
    Thanks guys.  Earth size to the house won't be a problem as customer wants a 16mm 3 core SWA  put in anyway.  



    Gary

Community Rules & Guidelines