Insulation Tube Type For Underground Incomming Mains

[JohanB]

Hi,

I am going to dig down an 1 phase incomming 220V mains cable from a 15/45A meter. The last 50 meter will go underground between a ordinary cement pole and the house.

I already have 2 spools x100meter of THW 16mm2 copper 750V copper wires from BCC and will run them through some sort of sleeve under ground.

Anyone have experience of what type of sleeving to use when digging down the cables.

I have to chose from the yellow PVC tubing, with glued or unglued joints, or one continous length of the black 25mm PE (Polyethylene tubing commonly used for underground water suplies).

My thoughts about this are:

1) I am a littled worried about having standing water in the tubes for ever or maybe it does not matter...

2) With unglued joints, the water, that always will leak in, also has a chance to seap out....

3) With the PE tube sleeving I can seal the open ends with silicon and protect them from direct water (raining or submerging) and hope no water will be there for ever.....

4) Glued joints yellow PVC piping with silicon sealed ends and hope no water will be there for ever...........

Does any experienced member here around have some serious conciderations about this??

/JohanB

[Crossy]

Firstly I wouldn't use THW it's really intended as a building cable intended for use indoors inside conduit or trunking, an insulated and sheathed cable such as NYY would be better for your tails.

Whatever cable you decide on you should use a tube of HDPE, usually black with a red tracer to indicate electrical service, should be readily available all over as it's used by PEA for their underground services. Make it plenty big enough for your cables so you can replace them easily should they fail.

PU foam topped with a thin layer of silicon will keep the wet and wildlife out but will be easily removed to replace the cable.

If your area is prone to flooding I would reconsider using underground services and go overhead for reliability.

[JohanB]

Thanks Crossy for the suggestions.

This was a graet tip on that point out the HDPE tube. Is that High Density PE or what stands the HD for?

Also a great idea of sealing with PU-foam and silicon on top of that.

It is quite dry land at an altitude of 300m leaning terrain, so we are at no risk of flooding at all. Only seasonal heavy rains soaks the ground as everywhere here.

All wiring will also be inside our land, so nobody else is going to suffer for a bad installation.

What danger or disadvatage can you see in using the 16mm2 THW-cable in this application? This is the common cable also used for overhead wiring in this remote countryside area of Mae Wong?

/Johan

[electau]

Single core PVC insulated PVC sheathed is another way of describing the cable you require.

[Crossy]

Single core PVC insulated PVC sheathed is another way of describing the cable you require.

Indeed My thinking is that using the Bangkok Cable designations gives us something that our local sparks will understand