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  1. Graham Hyde

    Graham Hyde Guest

    I am busy doing some work with a local contractor to get some up to date hands on experience.
    whilst doing a EICR today i come across a CU with SPD in. The property is a recently built 5th floor flat about to be let on a new tenancy and meets the criteria for requiring a SPD. The whole set up is all Hager products.

    Having only briefly come across these before and never been involved in installing one I am a little unsure of the method.

    i have gone and looked on Hagers site. They suggest both the 32A MCB and SPD should go in the CU after the 2 pole isolation switch but before the RCD's and other circuits.

    Hager - Surge Protection Kit Videos -

    The installation I came across has the 32A MCB immediately after the isolation but the main SPD is at the end of the CU after all the circuits.

    I have enclosed a picture, its is not too clear as the camera flash created shadows in the cupboard, but i have highlighted the relevant parts with Red arrows.

    Can somebody tell me if this is the correct or acceptable method of installation or should it be installed as per Hagers own video? Surely, the SPD needs to go before all circuits otherwise damage would potentially be done to circuits before reaching the SPD?

    Finally,Other than the green life indicator built into the SPD how do you test one? The company I am doing some experience with simply said if its green you are happy if its red change it.

    Any advice would be appreciated. As i am led to believe these things are becoming more common, especially in new installs.

    View attachment 35959
  2. polo1

    polo1 Electrician's Arms

    Business Name:
    GW Electrical & Security
    Be interested to see how it's actually wired, but my understanding too, is that SPD should be installed as close to the main switch as possible
  3. Graham Hyde

    Graham Hyde Guest

    Thanks for the reply. i forgot to upload the internal wiring picture last night. its not great quality as i took it on a phone in a dark cupboard. you can see the mcb and spd are at opposite ends of the CU. like yourself i thought both had to go next to the main switch rather than be spaced out.

    View attachment 35969
  4. Rob

    Rob Trusted Advisor

    North west
    It should be mounted as per the pictures in an ideal world.

    However at that distance, there won't be any issue. An you can't really test them, effectively like a fuse once it's blown it's done it's job an needs replacing.
  5. LeeH

    LeeH Insert witty monkey comment here. Electrician's Arms

    Do we get a lot of surges in the U.K?
  6. Rob

    Rob Trusted Advisor

    North west
    If you do a risk analysis on lightning strikes, you'd be surprised at how many installations should have them fitted.
    • Like Like x 1
  7. mydigitalhome

    mydigitalhome Regular EF Member

    Surge is not just about lightning strikes check out the Dehn manual or Wylex install brochure etc (other makes available) it provides other benefits too.
  8. spinlondon

    spinlondon Trusted Advisor

    Harlow Essex
    SPDs are wired in parallel with other circuits.
    As such where in the board they are positioned isn't really an issue.
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