Tool for digging very narrow trench - can't remember name

[d000hg]

I while ago I was looking into getting a cable laid under the private road between our house and garage. The option to dig a standard trench - say a 1 foot wide exists, and re-tarmac after.

But somewhere on the internet someone suggested a special tool which can dig a trench about a inch wide and a foot or so deep into which a cable can be dropped. I think it was a bit like a massive angle-grinder but I can't remember what it was called - can anyone help me out so I can know what to look for at tool-hire places?

It seems to me this would be ideal - quickly cut a tiny trench, drop an armoured cable, and make good, far more quickly than digging a proper trench.

I found this kind of thing for instance:

 

[foxhole]

http://trenchcut.co.uk/Trenching.html

 

[d000hg]

Wowser those are some serious machines! Not quite what I've seen though - we only need a trench about 8m long. I assume those things would be able to cut through tarmac and hard-packed stuff but I'm sure I saw something specially for laying cables under a road.

 

[d000hg]

I guess according to this I'm after a "microtrencher" http://en.wikipedia.org/wiki/Trencher_(machine)

A chain-trencher unit - a small walk-behind one - might work but all the examples show it being used on gardens, not tarmac on top of hard-packed gravel.

However all the microtrenchers I see are big ride-on jobs. For what I describe, do I need a special tool in the first place or would a serious angle-grinder type tool be adequate?
I need to get probably a foot deep as when I say "private road" it's essentially a driveway with no through-traffic.

 

[big-all]

wall chaser but worth a mention
http://www.lidl.co.uk/cps/rde/SID-6...fers-2491.htm?action=showDetail&id=10844&ar=1

 

[d000hg]

I don't think that's going to be deep enough!

 

[foxhole]

https://www.youtube.com/watch?v=qXD2x2_fIJU

 

[GaryGarden]

You need to ask this on the sparks forum, there are rules about how deep you need to go regarding the trench depth not to mention cable sizing and termination. You can't just drop a length of SWA into a channel, not if you want to sell your house in the future anyway, you must work within the regs or face an a*** ache in the future.

 

[d000hg]

Thanks for the tip. I will ask there about such things but I am still keen to find the right tool first. In fact this is partly why I am worried about being able to go deep enough.

foxhole's video seems pretty much perfect but none of the toolhire places I looked at had such things.

 

[ntb]

The regs call for a minimum 500mm trench with soft sand under and over the cable and warning tape over the top of it iirc. I think you will have to go wider and deeper if you want it signed off and compliant.