Running cable through a cavity/ protection required?

Discussion in 'Electricians' Talk' started by ShabbaPlanks, Jul 29, 2006.

  1. ShabbaPlanks

    ShabbaPlanks Member

    I am redoing the electric for my pond, correctly this time around. I wish to install an MK double gang active RCD on the outside wall. This will be fed by a switched 13a FCU which will be fed from a socket on the ring which has no spurs on it.
    I hope to pass the cable straight from the FCU through the cavity wall into the back of the MK box.
    Should I drill a 20mm hole for conduit and then pass the cable through?
    Will the conduit ends need sealing?
    Should I seal the back of the MK box to the brickwork?

    I currently have a weather sealed box on the wall which feeds a pump and UV unit. Weather sealed box is fed by a 13a flex through the wall and a plug in RCD on the socket I wish to take a spur from. Once I have fixed the new MK RCD on outer wall I intent to plug the 13a flex into there. Will this be OK? Or do I need to consider something else.

    I would like to use either this http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A431887&ts=93019&id=31502 or this http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A431887&ts=93075&id=39129
    For the FCU. The reason I am looking at the neon is I wondered whether it would be possible to link the neon to the RCD so that I would know if it has tripped, If possible, would it be inside regs?
     
  2. Rabbit Rabbit

    Rabbit Rabbit New Member

    I assume that your consumer unit does NOT have RCD protection to the circuit you propose to take the supply to the external socket (you should NOT have two RCD's on same circuit unless they differ in sense current values (higher value upstream).

    If you need to fit an RCD then you probably be better of installing something like a Powerbreaker 30mA fused (13A or less) spur unit inside the house and MK Masterseal on outside wall. Rather I think you will find it a cheaper option.

    Yes drill 20mm though wall and ram 20mm conduit through wall and across cavity and beyond the outer wall to protect cable (t/e assumed). Then fit a right angle conduit bend on the outside part and take this UP and into the MK Masterseal using a coupler. Do not go through the back of the Masterseal nor the sides nor the top unless its the only option. Always feed from underside wherever possible and if you do drill out the special drain hole within the MK Masterseal unit.

    The newer Powerbreaker RCD/FCU uses illuminated indication that power is on.
     
  3. ShabbaPlanks

    ShabbaPlanks Member

    Thanks Rabbit
    I will tap through to the MK from undeneath. Yes T+E 2.5mm. The consumer has no RCD protection so I do require an RCD.
    Would like to stick with the cragtree FCU as we have replaced all the other sockets and it would be a shame to have a ***** RCD on the wall. Using e-bay for my purchases so cost is low, I wait for the bargains.

    Do you think it would be possible to switch the neon with the RCD as opposed to the FCU? This is so I can know if RCD has cut power to pond.
     
  4. X

    X New Member

    Should drill the hole at a very slight angle, so that in the event of any water geting on the conduit, it wont go onto the inside wall..

    However, this causes another problem in that the bend wont be at exactly 90 degrees to the outer wall, but can be corrected with a slight curve on the upright.
     
  5. Rabbit Rabbit

    Rabbit Rabbit New Member

    X raises a good point, always angle the hole such that any water penetration is unable to run "up hill" and hence into the conduit/cavity etc. Using plastic conduit and using a slight angle when drilling you should be able to take out any non-90 degree that X refers.

    I doubt very much that you will be able to use thne neon to indicate active power to pond. In most instances the neon is hard wired to the output of the fused spur. This output is the feed INTO the RCD and the output of the RCD goes to pond. The only real way would be to have a small indicator alongside the fused spur or drilled within the same and feed a connection using 1.0 t/e back up from the output of the RCD to this indicator.
     
  6. Clark Kent

    Clark Kent New Member

    install an MK double gang active RCD on the outside wall. This will be fed by a switched 13a FCU which will be fed from a socket on the ring which has no spurs on it.<


    :)
     
  7. ShabbaPlanks

    ShabbaPlanks Member

    Cheers X, a very good point and something I would not have done had you not pointed it out. Will it be OK to put a dob of sealant in the conduit, just in case of drafts?
    Nice one on the indicator Rabbit. I will wait till I get my hands on items to see whats possible. Might just post another topic :)
    Ext15 did I get it wrong? I have had to take on silly amounts of info in the last few days. My appologies for previous silly posts I have made in the sparks forum, a little knowledge is a dangerous thing ehh...;)
     
  8. X

    X New Member

    a little knowledge is a dangerous thing ehh..

    Aint that the truth
     
  9. Rabbit Rabbit

    Rabbit Rabbit New Member

    ......... My appologies
    for previous silly posts I have made in the sparks
    forum, a little knowledge is a dangerous thing
    ehh...;)

    No such thing as a "silly question" none of us know everything.
     
  10. sparks

    sparks New Member

    Hi RR I use those special drain holes in all adaptable boxes etc, make them with a drill,;-) water will get into anything in time but its not a problem if it can get out again.
     

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