Sealing underground ducting at DPM

I'm having a concrete base laid for a garden studio. It will have a DPM.
Services (water, electrics, LAN etc.) will be provided via 100mm ducting.
The ducting will come up through the DPM and concrete.
How do we ensure a good damp proof seal between the ducting and the DPM.
Thanks, Roy
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On Monday 13 May 2013 03:37 Roy Brophy wrote in uk.d-i-y:

Easy - you do not fuss too much. You are reducing damp travel, not making a tank.
If the duct comes up through a tight hole in the DPM, that's good enough.
BTW - I would use 2 ducts and smaller than 100mm - Mains by itself (it should be spearated from ELV (lan, unless lan is fibre) and also from the water). Water and lan could be run together but it would be more sensible to separate. Water could just as well be buried direct in the ground as blue MDPE - it usually is. You could use a short bit of duct to take the water through the slab to make furture replacement easier, but it might as well be direct buried in plain ground between the building as the house.
63mm should do it:
http://www.ebay.co.uk/itm/63MM-X-50M-RIDGICOIL-FLEXIBLE-CABLE-DUCTING-BLACK- NEW-/180695624285#vi-content
Actually for the price, and the fact you are buying a 50m coil, you could lay in 3 lengths and have the water in one...
You could also easily re-ebay the left over - someone always wants less than 50m.
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On Mon, 13 May 2013 09:36:07 +0100, Tim Watts wrote:

Not a good idea. Someone comes along later sees three blue "water" pipes but gets a "surprise" when they discover mains in it when hacking through it. Clamping off works for water/gas but not electrickery. B-)
Slightly more "fail safe" would be to use black as that should be power and getting a bit wet is not as dangerous has hacking into a surprise live mains cable.
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On 13/05/2013 10:24, Dave Liquorice wrote:

But you could always lay "electrical hazard" tape over it (in fact you should anyway).
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On Monday 13 May 2013 10:24 Dave Liquorice wrote in uk.d-i-y:

? I didn't say to put the cable in MDPE.
I was suggesting 3 runs of duct - which could be bought as red or black (as you suggest below) if you were worried.
The electric duct out to have yellow marker tape laid above it anyway as a warning.

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Many thanks for the responses.
Very helpful.
Roy
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