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Hager Surge protector

goldenboy1818
Hi guys


Fitting a hager surge protector in a board and its all pre wired. Just wondered about something, it has a earth fly lead up to the main earth bar, but also another earth terminal on the bottom of the device.. is this needed ?? I havent fitted many as in the area where iam and small domestics we haven't needed to install them. Thanks guys
  • 0
    Can't be sure without seeing it, but many of the Hager SPDs have two earth terminals next to each other - AFAIK they're connected internally - so with short connecting leads you can just use one.


    Having the 2nd terminal is handy when you need to loop through the earth connection when otherwise the connecting leads would be too long - like the arrangement in Fig 534.9 (page 170) of BS 7671 - but the two earth terminals on the SPD taking the place of the extra "intermediate earthing terminal" (2).


      - Andy.
  • 0
    You can also use the second SPD Earth terminal to make a short connection to the nearby chassis - this provides a second path back the earth bar which, due to it being a flat sheet of steel, doesn't suffer from the same inductive effects that makes long leads from the SPD bad. (I don't pretend to understand the physics behind this - I'm just parroting the BEAMA advice).

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