Black with a red trace is normal for underground power, if you can keep it in one piece it stands a chance of remaining dry.

1 piece is the trick for sure... there is close to 500 meters is needed so it's going to be a challenge sure.

From what I can see Thai Watsadu has 50 meter rolls. If I can get my hands on 100 meter rolls chances of it staying dry are much better. =)

The NYY cable is rated for direct burial as it has a tough high density plastic sleeve on the outside. I looked into putting it into conduit when we installed our run but an electrical contractor friend in the USA recommended not doing it as the conduit virtually always fills up with water. Also note that it is sometimes very difficult to pull the cable into the conduit or tubing. I found that out in the 3 meter section of conduit that runs into the house.

+1 on that T_Dog.

I've never seen it in aluminium, and as I noted earlier, I strongly suspect that MEA/PEA don't allow aluminium underground.

@crossy... I'm asking if you know whether or not the black and red conduit comes in 100 meter lengths or more. I'm clear on the copper vs aluminum. Thanks again.

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And from what you and Tdogg seem to imply, threading 2000 meters of 25m sq cable through 500 meters of any conduit will suck.

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If you go to one of the electrical wholesalers you should be able to get long lengths of the stuff, the actual amount on a drum varies with the conduit size.

When the supply authorities use conduit, sections are welded together, if you can find a contractor with the kit to do this then you can have as much as you like in one piece, failing that you should be able to get joiners from the same place as the conduit.

Getting the cable into such a long run will need specialist kit as well.

To be honest, I would be direct burying NYY, get it deep enough to be beyond the range of gardening activities and it will be as safe as using conduit.

I need to do this sooner or later, overhead (as in you have to duck when going around) cables are decoratively festooned all over the place, we have two houses in our compound and a third is on its way. My only worry, apart from the cost, is to find a contractor that is capable of doing this.

As for welding, I had thought to leave conduit ends above ground, protected of course, that should solve the water problem. Not a solution if you have 500 meters to do of course.

I have experienced a "minor fire" due to NOT using NYY and NOT using proper HDPE conduit. For 3 front gate lights and a door bell. That yellow pvc filled with water, the copper wire (not NYY) corroded and it could have been real bad. The only part of our electric service NOT on the house electric plans, this gate lights and door bell wire was an "extra not on the original budget" item. Now we do have NYY for the lights, doorbell, and it is underground in proper HDPE black conduit. Home owners insurance covered the fire damage and destroyed electronics in the house, but if I was not home and heard the 299 baht surge protector explode into flames it could have been a different outcome. NYY and the proper black conduit is available at any "electric shop" and certainly Thai Watsadu or Global House.