Can someone please advise me of the best practice for chasing ( and finishing) a slot in a plaster + brick/ breezblock wall to take power and video cables from about 2ft off the floor to behind the screen ( 6ft high). I have purchased a wall mount for the screen, and some conduit to house the cables and a stone cutter attachement for a drill.

Thanks for any advice

JohnB wrote:
Can someone please advise me of the best practice for chasing ( and
finishing) a slot in a plaster + brick/ breezblock wall to take power
and video cables from about 2ft off the floor to behind the screen (
6ft high). I have purchased a wall mount for the screen, and some
conduit to house the cables and a stone cutter attachement for a
drill.


I'm not really sure about best practice but some observations...

1) Embedding a power cable in the wall will be covered by electrical
regulations. Read up on what your'e doing in some IEEE literature, but
as a starter the most relevant regulation is that you can hide a cable
in a wall in a horizontal or vertical line from a visible electrical
fitting (usually a socket or light switch) or within 15cm of the sides
and top of the wall. Anywhere outside of this area must be covered by
armoured or buried more than 50mm deep. Please note - I THINK this is
corretc. I have no doubt someone will correct me if I've made a
mistake. I have no idea whether a permanently fixed plasma screen
counts as an electrical fixing?

2) Chasing into plaster makes an unholy god awful mess. The last time
I did it I sealed the room with blankets and gaffa tape and it still
got out. Just chasing out three columns from ceiling to light switch
made me think I'd gone blind. I could not see a thing. Doing this
work with furniture in the room is completely unfeasible in my opinion.
I suppose you could manage it with a dedicated chasing tool and some
SERIOUS extraction power vented outside. A dyson is not going to cut
it.

3) Patch it up with plaster when you've finished. The appearance will
be down to your plastering skills. You could make it look perfect or a
complete dogs arse. When you cut into the wall cut at an angle so that
that the hole is a wedge shape this will help the plaster stay in the
hole.

I'm afraid that's all the help I can be.

--
Steve

In article , JohnB wrote:
I have purchased a wall mount for the screen, and some
conduit to house the cables

and a stone cutter attachement for a drill.

Don't even think about it on an occupied house - the dust will go
everywhere and still be reappearing in a year.

What I've done to get neat chases is to drill two vertical rows of
holes about 25mm deep either side of the chase which act like
perforations: you can then knock out the chase very easily (by hand or
SDS chisel) without shaking up the wall to much or loosening great
areas of plaster.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm
[Latest version QSEDBUK 1.10 released 4 April 2005]

JohnB wrote:

Can someone please advise me of the best practice for chasing ( and
finishing) a slot in a plaster + brick/ breezblock wall to take power
and video cables from about 2ft off the floor to behind the screen (
6ft high). I have purchased a wall mount for the screen, and some
conduit to house the cables and a stone cutter attachement for a
drill.

Not sure what your stone cutter is, but it sounds like it has the
potential to create dust in a big way. (anything angle grinder like -
i.e. rotating abrasive or diamond disc, will certainly cut a chase - but
will leave the room uninhabitable).

The neatest way I have found to chase walls without too much mess (using
machine assisted means) is with a SDS drill and an ordinary chisel bit
in it[1]. Cut a couple of parallel lines about an inch apart (or
whatever size you need), then break out the middle. The special chasing
chisels you can get for SDS drills can also work well, but I found them
more likely to dislodge large areas of skim coat if your plaster is at
all dodgy.

[1] You will still get as much mess as with a bolster and hammer
obviously, and it pays to have a good SDS with a speed control so you
can take it slowly and not spray fragments all over the place!

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"Tony Bryer" wrote in message
...
In article , JohnB wrote:
I have purchased a wall mount for the screen, and some
conduit to house the cables

and a stone cutter attachement for a drill.

Don't even think about it on an occupied house - the dust will go
everywhere and still be reappearing in a year.

What I've done to get neat chases is to drill two vertical rows of
holes about 25mm deep either side of the chase which act like
perforations: you can then knock out the chase very easily (by hand or
SDS chisel) without shaking up the wall to much or loosening great
areas of plaster.


Just completed this exact task ... although I used the lot's of holes
technique to sink the box ... (use the envelope masking-taped under
intended position to catch the brick dust); I 'notched' the two edges
of the vertical channel with an 88mm? (SDS) chisel from Screwfix
it's the same width as a single bac-kbox. This seems to give
a line of least resistance so that plaster doesn't flake at the edges.
The bits between the lines was hacked away with a 20mm SDS chisel - again
from Screwfix. I did cover the floor below the work with a bin-liner
bag masking-taped to the floor - {did I mention removing the carpet?)
and had an assistant holding a work-shop vac near the chisel. There
wasn't too much migration of dust.

BTW; the vertical channel must; -
#A;- go vertically iaw Regs ...
#B;- line up with one of the knock outs on the box!
It's unlikely that the box will have a knock-out centrally
so; put the box where it'll line-up with the channel


HTH

--

Brian

Thanks all, job was done as you recommended ( drilled holes 40 mm apart and chiselled out with 40mm chisel. Hardly any mess, and the grinder disc back in the toolbox ready for only outside jobs

Thanks all, job was done as you recommended ( drilled holes 40 mm apart and chiselled out with 40mm chisel. Hardly any mess, and the grinder disc back in the toolbox ready for only outside jobs