How to waterproof a cracked conduit pipe





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  1. #1
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    Default How to waterproof a cracked conduit pipe

    So Iím running a 220v cable inside an existing conduit and found a few places it is cut open - it runs through the veggie patch and isnít very deep so it is to be expected.

    Currently thereíre cables for the alarm and intercom system running through the conduit.

    Iíd appreciate ideas from forumites on how to best protect the cables at the points where it is cracked already.

    Going forward I can reorganise the layout of the veggie patch so that there wonít be digging above the pipe.

    Thanks

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    Default Re: How to waterproof a cracked conduit pipe

    Depends what type of cable you are using inside the conduit , remember that a conduit under ground is not water tight its more for protecting the cable, as the joints in the conduit will eventually allow some water in
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  4. #3
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    Default Re: How to waterproof a cracked conduit pipe

    I am not sure whether the 220 cable is in there already or just the intercom and alarm.

    Running 220 and low voltage in the same conduit is not legal and it will cause interference etc. The 220 cable should be waterproof as long as it is a legal cable something like twin + earth , norsk or armored cable. Not cabtyre or ripcord.

    Pvc conduit responds very well to PVC Weld and in theory you should be able to glue the cracks. If you have pieces missing a coupler cut in half will do the trick.
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    Default Re: How to waterproof a cracked conduit pipe

    Never run alarm and 220 cable in one conduit. Do not run gate phone and alarm either. For some reason gate phone is more suspect to lightning.

    Only way to prevent damage is to dig deep or cover with concrete or similar.

    As said conduit is not there to keep cables dry. There are cables that get damaged by water - cheap Chinese (experience). Also even armored 220 cable can be damaged if not deep.

    If you have to make a joint on 220 V cable you have to use epoxy filled connection boxes. I assume they work also for alarm/gate phone wires.
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    Default Re: How to waterproof a cracked conduit pipe

    Quote Originally Posted by hbannink View Post
    Running 220 and low voltage in the same conduit is not legal and it will cause interference etc. The 220 cable should be waterproof as long as it is a legal cable something like twin + earth , norsk or armored cable. Not cabtyre or ripcord.
    🤨 It took me the better part of a day just to get the 220 through the conduit to the desired spot. Just finished tonight

    Back to the drawing board then.

    Thanks yíall

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    Default Re: How to waterproof a cracked conduit pipe

    Next time run the cable before glueiing the coduits together or pop round I will lend you my fish tape makes life sooooo much easier
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    Default Re: How to waterproof a cracked conduit pipe

    Cut a piece of spare conduit, longer than where the crack is, cut the piece length wise to split, slide over damaged conduit, first ensure to glue with proper PVC cement,

    PVC weld is rubbish, proba ly the reason you mention the joints will start leaking

    Rather use PVC cement made for pressure applications such as Oatey or Tangit

    Alternatively take some shavings from the conduit and mix with PVC Cement and plug the hole

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    Default Re: How to waterproof a cracked conduit pipe

    Best advice I can give is reroute conduit away from veggie garden if not, repair pipe as mentioned then drop conduit down to 500mm into a trench. Do the same with the 220v supply in a separate conduit.
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    Default Re: How to waterproof a cracked conduit pipe

    Quote Originally Posted by hbannink View Post
    Next time run the cable before glueiing the coduits together or pop round I will lend you my fish tape makes life sooooo much easier
    To my shame I had to Google fish tape I used a pilot / guide string (piece of electrical fence wire) and something like this would've helped a lot but I'm going to yank it all out now anyway.

    I'm not very handy - I get myself into trouble too often, like with this 220v too close to the low voltage wire Sometimes I think stuff like this ought to be taught in schools but I doubt I would've paid attention

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    Default Re: How to waterproof a cracked conduit pipe

    If you ever have to lay a cable/conduit shallow just put a single layer of bricks sideways over the conduit in the trench. This way one will soon find out there is something in the way before a fork/spade damages it.

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    Default Re: How to waterproof a cracked conduit pipe

    In order to prevent me opening myself up to some possible criticism here... let me just say this is for a friend...

    A guy ran an electrical cable 2.5 mm2 twin and earth from the house to the outbuildings. The cable was pulled through a high quality (recommended by a plumber) thick black high pressure water pipe.

    That was maybe 15 years ago, and then about 6 years ago he pulled CAT 5 cable in the same black pipe. No problems to date.

    A qualified electrician told me that was a bad thing to do, even before the data cable was pulled in, but he could not give any reasonable explanation.

    My thinking was that I have the electrical properties sorted in the twin and earth, and the water pipe is providing better mechanical protection than I would get from electrical PVC conduit.

    I have a similar requirement again, and if I don't get a bad report here, I will do that again. Would that be a good option for the OP?
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    Default Re: How to waterproof a cracked conduit pipe

    MarcR`s suggestion of replacing the PVC pipe with a HDPE pipe is not a bad idea, thick walled HDPE can take a lot more abuse and offers great protection. In industrial setting we use Nextube conduit that is manufactured out of HDPE.


    Running an UTP cable in parallel with a AC power cable wont present any real world issue with the network cable. UTP cable is unshielded TWISTED PAIR. These twists between pairs reduces the crosstalk between conductors, the one difference between CAT 5 and CAT 6 UPT cable is that CAT 6 has a higher number of twist per meter, allowing higher frequencies and hence higher data transfer rates . A shielded cable will work even better to eliminate electromagnetic interference from the 50 Hz power cable. But its not in line with our local regulations as UTP cable insulation is not rated for 220V . In the case where CabousBeer spits trough the power cable and network cable with his spit fork the 220V AC can flow trough the network cable and fry all his IT gear, set his house on fire, and electrocute the poor sod working on the 386 DX.

    Best practice is to make sure the cable is buried deeper than what anyone would ever spit. Make sure the cable has mechanical protection. In cases where this is not possible the cable must be protected by an Earth Leakage device. Never run power cables and signal cables in the same wireways. If they need to cross, make sure they cross at a 90deg angle. Alarm cable is not twisted pairs its usually super cheap 0.00005mm2 copper if you are lucky but the signal is either on or off, so EMI not really an issue here.

    For interest in industrial settings this is taken really seriously:

    0.08.00 INSTRUMENTATION CABLE INSTALLATION AND ROUTING

    10.01.00 All cables assigned to a particular duct/conduit shall be grouped and pulled in simultaneously using cable grips and suitable lubricants. Cables removed from one duct/conduit shall not be reused without approval of Employer.

    10.02.00 Cables shall be segregated as per IEEE Std.-422 and IEEE 524 (1992) In vertically stacked
    trays, the higher voltage cable shall be in higher position and instrumentation cable shall be in bottom tier of the tray stack. The distance between instrumentation cables and those of other system shall be as follows:

    From 11 kV/6.6 kV/3.3 kV tray system - 914 mm
    From 415V tray system - 610 mm
    From control cable tray system - 305 mm



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    Default Re: How to waterproof a cracked conduit pipe

    Quote Originally Posted by CabousBeer View Post
    To my shame I had to Google fish tape I used a pilot / guide string (piece of electrical fence wire) and something like this would've helped a lot but I'm going to yank it all out now anyway.

    I'm not very handy - I get myself into trouble too often, like with this 220v too close to the low voltage wire Sometimes I think stuff like this ought to be taught in schools but I doubt I would've paid attention
    Easy one is to bend the tip of the electric fence wire back on itself. Not knowing a fish tape is no crime, it was my trade for many years, there are a lot of simple tricks you pick up in the lines like putting Mazina in to the conduits to lubricate the wires and Never using soap as it dries and then is as good as glue.

    @ Marc, 15 -20 years ago the regulations were much higher than now, then we had to put 2 + e in a "mechanical" protection, the black pipe is about 10X the strength of the flimsy conduit that was deemed to satisfy.
    In those years conduit had to have the SABS stamp otherwise the inspectors would fail the job and cost you a lot of money to sort out. Pretty soon non SABS "white pipe" became available and was used for primarily protection for intercom cables but also for chasing in to walls where inspectors could not see, saved a packet. Nowdays the wire must be protected even if it is just under 100mm soil it is fine no more 500mm at least and then conduit unless it is armoured cable. I used to keep my trenches open for the inspectors to see otherwise they would make you open every so often so that they can see

    The reason for the separate conduits for low and high voltage besides interference is the transformer effect. A normal transformer uses a long wire wound around a metal core and a second wire also wound the metal core. Magnetic induction happens and a new current is induced in the secondary winding. A high voltage in close proximity of another line especially a 2 +e is as good as a transformer. Magnetic flux can do nasty things ie. a fluoressent tube glows when brought close enough to HT lines and other strange things like that.
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    Default Re: How to waterproof a cracked conduit pipe

    We had lighting related problems in the main house because different type wires were in same conduit or too near each other. It is really not worth to do it.

    Just now we have an issue with electric fence high voltage wires. There are three in one conduit to cross an area where no fence is in place. They have failed for what ever reason. I had a look. The conduit is not 100% straight. There seem to be some bend or change in direction. If it was one wire it would be easy to pull an other. Now it might be an issue. We will see after the lock up. Do not put too many wires. One is the best.

    Conduit has joints and there is a good change that some fines will get in when buried. After that wire replacement can get an issue.

    Black water pipe has no joints, put it deep enough and get ends on top and seal them. At least in factories rodents use conduits to move around.

    At the cottage we have old cables near the surface. Regularly armored cable is damaged by digging, tent spike or what ever.

    If you want to find and electric cable or water pipe give a fork to a gardener. They have some king of accurate method of finding them.

    Schools do not necessarily teach everything. You learn them over many years especially when you have to fix an old installation.
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    Default Re: How to waterproof a cracked conduit pipe

    Quote Originally Posted by Jouko View Post
    There seem to be some bend or change in direction. If it was one wire it would be easy to pull an other. Now it might be an issue. We will see after the lock up. Do not put too many wires. One is the best.
    Using 1 wire in a conduit is really a waste and could be done outside at a home but not in industrial sites.

    The easy way is to adhere to the K factor assigned for each size of wire and how many of each size can be in a specific size conduit. Also that the maximum bends to be a total of 2 x 90 degrees between pull boxes along the path of the conduit. These K factors are very well worked out.

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    Default Re: How to waterproof a cracked conduit pipe

    Running an UTP cable in parallel with a AC power cable wont present any real world issue with the network cable. UTP cable is unshielded TWISTED PAIR. These twists between pairs reduces the crosstalk between conductors, the one difference between CAT 5 and CAT 6 UPT cable is that CAT 6 has a higher number of twist per meter, allowing higher frequencies and hence higher data transfer rates . A shielded cable will work even better to eliminate electromagnetic interference from the 50 Hz power cable. But its not in line with our local regulations as UTP cable insulation is not rated for 220V . In the case where CabousBeer spits trough the power cable and network cable with his spit fork the 220V AC can flow trough the network cable and fry all his IT gear, set his house on fire, and electrocute the poor sod working on the 386 DX.
    So I undid most of my dayís work in about 15 minutes today - yanking the cable back out.

    HDPE is a very good idea.

    Thanks for the info re. UTP

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    Default Re: How to waterproof a cracked conduit pipe

    Quote Originally Posted by hbannink View Post
    Easy one is to bend the tip of the electric fence wire back on itself. Not knowing a fish tape is no crime, it was my trade for many years, there are a lot of simple tricks you pick up in the lines like putting Mazina in to the conduits to lubricate the wires and Never using soap as it dries and then is as good as glue.
    Never used our mazina in ages, then today SWAMBO decides to make beet root salad and now that itís finished I need it to lube my 220! 🤪

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