Best way to seal 25mm conduit to exterior FCU

Discussion in 'Electricians' Talk' started by itisgeorge, Mar 16, 2022.

  1. itisgeorge

    itisgeorge New Member

    Hi all,

    I've installed an LED floodlight vertically above an FCU switch, and used some 25mm conduit and fittings that I already had. I've heard you never enter from the top, but I had no choice in this case.

    I planned to silicon around the joints but now realise it doesn't bond the best. My question is, without taking it apart again what's the best way to seal the FCU housing to the conduit female accessory, and also the conduit to the female accessory. See pic for context.

    PVC cement had crossed my mind, but not sure if you can apply that over an existing joint. Worth mentioning that I've drilled a drain hole in the FCU.

    Many thanks.

    IMG_4795 Large.jpeg

    P.S will also be sealing around the FCU, just waiting for some white sealant to arrive!
     
  2. Tony Goddard

    Tony Goddard Screwfix Select

    Unfortunately that will ultimately give rise to trouble. the adapter should be solvent welded onto the tube with appropriate solvent, which is done correctly will be watertight.

    The join between the box and adapter is more difficult. there is a flanged adapter available in the metal range, but alas not in plastic as far as i know.

    I have used No More Nails clear for seling things in the past, better than silicone as it doesn't tend to lift off.
     
  3. Ind spark

    Ind spark Screwfix Select

    You could try an ip washer, but you'd have to disconect for that.
     
  4. DIYDave.

    DIYDave. Screwfix Select

    Don’t these waterproof fittings have moulded ‘stand offs’ on the back of the box to allow water to pass behind them, and continue down the wall ?

    If you sili to wall, your encouraging more water to flow over the fitting …. I think !
     
  5. Bazza-spark

    Bazza-spark Screwfix Select

    Clean the end of the conduit and the adapter with solvent the glue the adapter as @Tony Goddard says. Then clean the box and adapter with solvent and use Sikaflex all weather sealant. That should last a good few years.
     
  6. Coloumb

    Coloumb Screwfix Select

    If you use solvent weld get the cable out and well away from the weld till it goes off. Solvent and pvc do not mix.
     
  7. Bazza

    Bazza Screwfix Select

    And drill a 6mm drain hole in the bottom of the switch box. You are going to need it.
     

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