Running wire under Ashphalt

exaisle

I want to run a 2.7mm wire on (or in?) hardcore before ashphlt is laid over the hardcore. Can anybody suggest a suitable conduit....it can't be metal as the wire is to be used as a guide wire for an automatic mower.

I understand that the hot ashphalt will be about 170 degrees C (which I'm assuming is too hot for the insulation on the cable) when laid so it
has to be non-metallic but heat resistant...

As an alternative I could dig a shallow trench and bury it in ordinary hosepipe...

knipex

Do not use ordinary hose pipe. too flexible.

Use plastic conduit.

You can probably get ti cheaper from electrical wholesaler, you can also get joiners, bends etc.. bury it a couple of inches under the hardcore and lay your drive on top.

keithdub

Does the lawn mower run over the asphalt? I would say plastic water mains it's small and thick. I would run 2 under the 804 incase one is damaged use a draw wire in them also.

exaisle

Yes...the cables (3 of them) run parallel to each other about a foot apart and act as a guide wire and two perimeter wires...

Do you mean Hydrodare? That might do the trick alright...the recommended maximum depth is 10cm.

I'd certainly include a second wire and a draw-wire. No point in skimping and being sorry later cutting up SMA with a con-saw....

punisher5112

You must use red electrical conduit as it's heavy duty.

Swa cable also could be used as it's got its own protect sheathing.

Victor

keithdub wrote: »

Does the lawn mower run over the asphalt? I would say plastic water mains it's small and thick. I would run 2 under the 804 incase one is damaged use a draw wire in them also.

Use an electrical duct, not a water pipe. Otherwise you risk mass consternation in the future when people find a water pipe when looking for an electrical duct and dig up half the driveway looking for the electrical duct.

exaisle

punisher5112 wrote: »

You must use red electrical conduit as it's heavy duty.

Swa cable also could be used as it's got its own protect sheathing.

I'll take a look at that heavy ducting thanks....but SWA is not suitable as the metal sheath would make its use as a guide wire redundant.

Do you know of anybody who supplies this...I'd need about 60 metres of 20mm diameter...or smaller if I could get it...

exaisle

Victor wrote: »

Use an electrical duct, not a water pipe. Otherwise you risk mass consternation in the future when people find a water pipe when looking for an electrical duct and dig up half the driveway looking for the electrical duct.

I take your point about possible confusion in the future, Victor, but there are three grooves cut in the pathway on one side and three more in kerbs on the other, so it should be obvious what's been done. Anyhow, the idea of using some kind of pipe or ducting is that it will allow me to install (a) an extra/spare wire and (b) a draw-wire so I can remove the originals and replace them, if necessary.

Del2005

exaisle wrote: »

I want to run a 2.7mm wire on (or in?) hardcore before ashphlt is laid over the hardcore. Can anybody suggest a suitable conduit....it can't be metal as the wire is to be used as a guide wire for an automatic mower.

I understand that the hot ashphalt will be about 170 degrees C (which I'm assuming is too hot for the insulation on the cable) when laid so it
has to be non-metallic but heat resistant...

As an alternative I could dig a shallow trench and bury it in ordinary hosepipe...

How does the mower work? I doubt that it's designed that you need to dig up your driveway or path if you are installing it in a garden so I don't think that you need to bury the cable under the tar. They are supposed to be convenient to use not require heavy machinery to install. The only one I've seen in action the wire is about 30cm from the concrete.

exaisle

Del2005 wrote: »

How does the mower work? I doubt that it's designed that you need to dig up your driveway or path if you are installing it in a garden so I don't think that you need to bury the cable under the tar. They are supposed to be convenient to use not require heavy machinery to install. The only one I've seen in action the wire is about 30cm from the concrete.

How the mower works

There's an area of lawn separate from the rest. The only way of accessing it is across a (soon to be) paved area. If the asphalt was already installed, I'd have no option but to cut a slit with a grinder or con-saw, install the wire and fill with tar but that would look ugly so I want to install the wires before the asphalt goes in...

punisher5112

exaisle wrote: »

I'll take a look at that heavy ducting thanks....but SWA is not suitable as the metal sheath would make its use as a guide wire redundant.

Do you know of anybody who supplies this...I'd need about 60 metres of 20mm diameter...or smaller if I could get it...

Any big builder supplies or electrical wholesalers should be able to order and deliver.

It's ESB grade stuff so not the cheapest but it's knowing it's done right and as mentioned always keep a pull wire in it in case you ever need to add any services.

Bruthal

Del2005 wrote: »

They are supposed to be convenient to use not require heavy machinery to install.

Convenient to use doesnt mean easy to install. Install once, use many times.

exaisle

Bruthal wrote: »

Convenient to use doesnt mean easy to install. Install once, use many times.

The cost of the mower includes the installation. The installers have a machine that buries the cable under the ground...the only inconvenient part is installing the cable under the asphalt.

Anyhow....apparently, the solution is quite easy according to the asphalt expert... Draw a narrow trench in the hard core and run the cable inside whatever kind of conduit you like. Cover the conduit with sand, and soak the sand with water just prior to laying the asphalt. The sand acts as insulation for the conduit long enough to allow the asphalt to cool to the point where it won't damage the conduit.
Simple really...when you know how...