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 11 replies
  • Subscribers 32 subscribers
  • Views 2093 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

TT CT2 SPDs and TN requirement

wallywombat
534.4.6 says that for TT systems where an SPD is upstream of the RCD, then a CT2 SPD must be used (fair enough), but also says that "the conditions of Regulation 411.4.1 shall be met". But 411.4.1 is about TN systems having a dependable connection to earth. In particular:
411.4 TN system

411.4.1 In a TN system, the integrity of the earthing of the installation depends on the reliable and effective

connection of the PEN or PE conductors to Earth. Where the earthing is provided from a public or other supply

system, compliance with the necessary conditions external to the installation is the responsibility of the distributor.

I don't get why a section about SPDs in a TT system refers to a TN requirement.
Parents
  • 0
    Perhaps in view of it's doubtful usefulness and the apparent vagueness as to it's correct installation, then maybe BS7671 should allow an exemption for use.

    I have a job coming up on a TT supplied installation whereby a new consumer unit will be fitted in addition to the existing set-up. I wish to elect to use a CPFUSEBOX item with a T2 SPD and main switch. The unit comes with a B32A mcb to protect the SPD and the subcircuits will be covered by individual RCBOs.

    The only info I can see is that their SPD is labelled T2.
Reply
  • 0
    Perhaps in view of it's doubtful usefulness and the apparent vagueness as to it's correct installation, then maybe BS7671 should allow an exemption for use.

    I have a job coming up on a TT supplied installation whereby a new consumer unit will be fitted in addition to the existing set-up. I wish to elect to use a CPFUSEBOX item with a T2 SPD and main switch. The unit comes with a B32A mcb to protect the SPD and the subcircuits will be covered by individual RCBOs.

    The only info I can see is that their SPD is labelled T2.
Children
No Data

Community Rules & Guidelines