Sam wrote:

What is the best way to chase walls for cabling? I read the wiki FAQ
and it talks about making two lines with an angle grinder and then a
bolster chisel to knock out the bit between. That's what I have been

It works, but only if you like dust!

One of the proper wall chasing machines that uses two angle grinder
blades and has a housing to control the dust is better.

doing. I am using a 115mm angle grinder which is cutting about an inch
into the wall. That's as far as it will go. It's cutting about 10mm of
plaster and 15mm of breeze block. Is that deep enough or do I need to
use a chisel to go deeper?

Plenty deep enough. If you use oval conduit for the cables you only 10mm
of depth or so for the conduit.

The angle grinder is making some nice deep lines, but I am not getting
a clean cut of the gap between the lines. The breeze block is very
rough. What is the best way to get a smooth finish? Do I need to
sharpen the chisel? Could it be blunt?

You don't really need a smooth finish - as long as the trunking can sit
in the chase deep enough to get covered up later, you should be ok.


What is the best thing to drop the cable in? Wickes & Screwfix sell
some channeling, which is a bit like a gutter. The problems I see with
this a
1. plaster could get round the back and onto the cables or block the
channel
2. the wire could scrape against the rough surface of the wall

This is capping - only really any use for protecting cables prior to
plastering. Not much use for your application.

Wickes also sell the same in metal. I guess the metal offers more
protection against drilling/nailing through the cable but does it have
to be earthed? If it became live I cans see that could be very
dangerous.

The thin metal stuff offers little more protection against nailing etc
than the plastic. The main benefit is that it stays where you bend it a
little better.

I see the wiki uses proper conduit, which would avoid both of my

What this one?:

http://wiki.diyfaq.org.uk/index.php?title=Wall_chaser

problems above, but if it is 20mm in diameter, it would only be 5mm
beneath the surface. Would that be deep enough? How do you hold it in
place whilst the plaster sets around it?

If you use the oval 22mm conduit:

http://www.tlc-direct.co.uk/Products/MTOV20.html

the depth is only 11mm

You can hold it in place with a blob of bonding plaster or gripfil etc.
Even just a couple of large head clout nails.



--
Cheers,

John.

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