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  1. #1
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    Water in conduit

    The recent storm flooded my trench containing 2 x 25mm Al cable in it's 3/8" yellow conduit - each more than fifty metres long.

    Unfortunately, water has gotten into the conduit, which I will attempt to blow out. I think I've got air passage (lung power!) but it's so restricted that it will need a decent pressure to be able to dry out. Don't want to have to buy a compressor I don't need so hoping to be able to rent a compressed air tank, but know how averse to renting Thais are!

    Any advice, please?

  2. #2
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    Buy an electric blower from Tesco, Big C, et al.



    Not expensive. Just don't aim it at the cat if you ever want to see him again.

    If there are no shorts eventually all the water will evaporate.

  3. #3
    Days Work Done! Norton's Avatar
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    Try Namsang for rental of air compressor.



    Tel +66 53 853-080

  4. #4
    Days Work Done! Norton's Avatar
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    Quote Originally Posted by VocalNeal View Post
    Buy an electric blower from Tesco, Big C, et al.



    Not expensive. Just don't aim it at the cat if you ever want to see him again.

    If there are no shorts eventually all the water will evaporate.
    Could work. Depends on amount of water. Best to find where the water entered and repair.

  5. #5
    Thailand Expat Pragmatic's Avatar
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    Water in underground conduit is not a problem. Plenty of info on the subject in Google. Water-filled Conduit

    Edit:-
    Conduit is a mean of protection for the conductors from physical damages, not for waterproofing. Underground conductors must be rated for wet location. No matter how hard you try to keep them dry, water will find a way through.
    http://www.garagejournal.com/forum/a...p/t-71123.html
    Last edited by Pragmatic; 26-03-2015 at 11:57 AM.

  6. #6
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    Great idea!
    Hadn't thought of one of those. I hope it will cope with a low initial flow rate without overheating.

    I've a 12V lilo pump, but that wouldn't be powerful enough.

    The water came in through one end where I've put a JB for the riser into the house but had not yet sealed the ends with silicone to prevent ingress of water - and ants, of course. Conduit has been sealed (I hope) along its length with solvent cement

  7. #7
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    The cats can take their chances!

  8. #8
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    Quote Originally Posted by VocalNeal
    Buy an electric blower from Tesco, Big C, et al.

    Just make sure you turn the electric off before you perform this operation , incase of a short circuit

  9. #9
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    Could you remove the cable from the conduit, dry it, then put it back (sealing it all straight away afterwards)?

  10. #10
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    555 sorry to be somewhat anal but 25mm is about 1 inch....two in 3/8" conduit..typo?
    555...Rather than just blowing you could suck or blow using a wet dry shop vac at one end ..with some judicious use of duct tape perhaps?

    As for the problem..if the trench has drained I would be inclined to dig a soak away or two to keep it that way. Is the aluminum cable same as made for aerial use? Heavy gauge insulation on that stuff .
    Would not worry about drying the conduit...if the water got in it will drain out methinks. Unless of course you have a short, in which case you'll need to do some digging anyway.
    I put ours from pole to house in about 10m of blue water pipe (did not have a long ladder or guts to do it aerial) ....did not glue or seal but it is on a grade.



    good luck.

  11. #11
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    No typo - there are two separate 3/8" ID plastic conduits, which I've sealed as best I can with solvent cement.
    Yes, the insulation is fairly good on the 25mm cable (denotes cross-sectional area of conductor). But I didn't select it for underground use. Will check in the morning.

  12. #12
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    By the way, yellow pipe is the standard colour for electric cable, though white is often used too. Blue (and green) pipe is for water.
    Dunno - doubt - if there are any Thai rules enforcing this. Might find out when I get a sparky from PEA to connect it all up.

  13. #13
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    Quote Originally Posted by crepitas View Post
    555 sorry to be somewhat anal but 25mm is about 1 inch....two in 3/8" conduit..typo?
    25mm cable has a diameter of about 5.6mm, plus the insulation.

  14. #14
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    For underground use the cable should be NYY spec.

  15. #15
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    Quote Originally Posted by Neverna View Post
    Quote Originally Posted by crepitas View Post
    555 sorry to be somewhat anal but 25mm is about 1 inch....two in 3/8" conduit..typo?
    25mm cable has a diameter of about 5.6mm, plus the insulation.
    Now you will have to explain that power cables are size by their area not diameter. Oops sorry i just did!

    OP did you get the water blown out yet?

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    A competent (!!!) local electrician has refused to put in a breaker and insists we should use triple-layer-protected cable instead of the 'recommended for overhead use' stuff another person I foolishly asked the advice of, who has installed same underground - without problems so far - in his resort. Proper cable is B200/m; installation, including burying, B500/m.

    We could take a risk, but I feel failure would be inevitable. Better sort it now.

    An expensive screw up!

  17. #17
    disturbance in the Turnip baldrick's Avatar
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    I am guessing you have used PVC / PVC ( individual / overall ) cable in your conduit.

    you need to understand that the conduit is for mecahnical protection , not for waterproofing.

    the PVC /PVC insulated cable should be fine submerged as long as the the water is not contaminated with some bad sh1t and the the ends are terminated with sufficient IP ( ingress protection ) .

  18. #18
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    Finally got a new cable installed: 2 x 16 mm NYY copper, PVC insulated and double sheathed.
    Pleased - and relieved - that the new house wiring seems to all be working okay. Only problem seems to be the pump; subject of another thread now...

  19. #19
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    That is good news..
    Curious to know by what mechanical means the transition between your OH and UG cable was achieved...ie how weatherproofed and terminated.
    When bringing OH cable via underground to house domestic distribution had to add a pigtail of smaller diam/area cable with bronze clamps ,covered 'em with lanolin grease,self amalgamating tape,electrical tape and then housed and sealed in a bit of fat BLUE pipe. ( although admit I did paint it yellowish...)

  20. #20
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    Quote Originally Posted by Tassini View Post
    For underground use the cable should be NYY spec.
    If you want to bury electrical lines in Thailand, this is the best choice as it is direct burial. It has a a double layer of PVC insulation and you never have water laying inside like you do with conduit. Stuff is not cheap, but you do not have to worry about it unless someone tries to dig it up!
    Press On Regardless

  21. #21
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    Armoured cable would do the trick, too.



  22. #22
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    When bringing OH cable via underground to house domestic distribution had to add a pigtail of smaller diam

    When my 25mm2 from underground NYY didn't fit in the 15/45 meter, my solution was to simply have the power company swap in the next bigger size meter of 33/99. Bigger meters accept bigger diameter cables.

  23. #23
    Days Work Done! Norton's Avatar
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    Quote Originally Posted by misterfloppy
    Only problem seems to be the pump; subject of another thread now...
    Lot's of threads on TD. Pump problems galore. Looking forward to yours.

  24. #24
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    Quote Originally Posted by misterfloppy
    2 x 25mm
    Quote Originally Posted by misterfloppy
    25mm cable
    Quote Originally Posted by Neverna
    25mm cable has a diameter of about 5.6mm
    Quote Originally Posted by misterfloppy
    2 x 16 mm
    Quote Originally Posted by canopy
    25mm2
    Right you retards

    I shall say this only once.

    You're confusing 16mm with 1.5mm
    and 25mm with 2.5mm

    1mm/1.5mm ok for low voltage LED lighting and such
    2.5mm for sockets.
    4mm/6mm for water heaters and cookers depending on the draw.

    You're welcome

  25. #25
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    Nope, I specified correctly.

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