wiring brick houses

Hi all,

I have a 100 year old solid brick house. I have had the wiring checked by a sparky mate. There are a couple of switch wires that need replacing(old cotton covered stuff). My mate is happy for me to run the new cable and he will then terminate it. he has advised me that I can only run the cable vertically.

Being rendered solid brick walls I have to cut trenches for the wire. I just got a diamond angle grinder blade to do this. I have a couple of questions. Do I have to/should I run the new cable in conduit, or just cut the trench insert the cable then plaster over the top. I'm thinking conduit would be best so the next poor sod doesn't have to cut the walls.

I also have the most detailed cornice I have ever seen, about 1 foot down the wall, and across the ceiling, with plaster rope with flowers along the bottom edge. I am not prepared to cut it, as you'd never be able to repair it. I was think of using long masonary bits to drill behind it up to the roof cavity. is this the best way, or can anyone think of another way to do this.

once again I will not be terminating the switch cables myself.

Thanks in advance
Moray

I think you would want to put the wire in conduit.

If you can get above the bricks wall and drill down below the cornice and then cut to your trench you would be OK.

Bunnings have a set of masonary drills (three) neally a metre long about 12mm to 25mm for about $35.

Hello Moray,

Yes, in conduit.

Can I also suggest that you go to Bunnings and buy one of the Ozito, GMC, Dynalink or some other el cheapo brand rotary hammer? Try and find one with a channeling bit included. These things are brilliant for running channels for conduit and you shouldn't have to pay more than $100.00.

Thanks for your quick replies.

looks like I have to go shopping at bunnings for some new stuff :D

I was going to make a pair of parallel cuts with the diamond blade, and chisel out the middle with a cold chisel. With the rotary hammer would you still need to make the cuts ?

cheers
Moray

Quote:

---

Originally Posted by Moray

I was going to make a pair of parallel cuts with the diamond blade, and chisel out the middle with a cold chisel. With the rotary hammer would you still need to make the cuts ?

---

Moray,
the parallel cuts with their sharp edges will make plastering over the hole soo much easier

ian

Quote:

---

Originally Posted by ian

Moray,
the parallel cuts with their sharp edges will make plastering over the hole soo much easier

ian

---

Yep. It's a good idea.

Solid brick or double brick? Double brick may have a cavity between the inner wall and the outer wall.

Cheers

it has double brick with a cavity on the exterior walls, however internal walls are single brick. unfortunately the switches are on the internal single brick walls.

what size conduit should i use for 1.5 twin switch wire, and a 1.5 single ( i.e. 3 wires, for a two switch light)

Hire yourself a wall chaser hooked up to a dust extractor.....then chisel out as suggested....quicker,easier,consistent depth,less dust !

Tools

Hi Moray,

If you haven't already started take Tools advice and hire a wall chaser with built in vacuum. I had a similar job to yours and tried the grinder but the amount of dust was unbelieveable and it gets everywhere. You'll end up having to clean all your decorative cornices. Also, you might not notice it after you're done but if you wipe the wall later on you'll see that a fine film of dust has settled over it.

if these switches are on walls that would let you chase horizontally to an exterior cavity wall you could do it that way to avoid the cornice, yes put it in conduit, its so much easier to fix later

Or you may be able to go down and across to a cavity wall

Doug

Our 125 year old house has cavity brick external walls and double brick internal walls. All internal walls are solid plastered and there are elaborate cornices, picture rails, vents and ceiling roses

Ten years ago I helped a sparky rewire light switches and install new power points.

We put all new powerpoints on the skirting boards on external walls. We just drilled a 25mm hole through the skirting and brick into the cavity, and then dropped a fishing line down the cavity and pulled the wires through.

The light switches are at shoulder height and we routed the vertical drop wiring into the plaster. First we tried using a router - quick but incredibly dusty. Then we used a small hammer drill - same result. Finally we cut two lines through the plaster with a stanley knife and steel rule and then hand chiselled the plaster out of the groove. The plaster was very soft and a hammer was not needed - we literally hand chiselled.

We then welded an 18mm drill bit onto 600mm of 6mm reo rod and drilled up from the top of the groove past the cornice. Really quick and easy.

We then ran the dropper wires, filled the grooves with cornice cement, hand sanded, touched up with cornice cement, resanded and painted wall.

It was a surprisingly easy job, but quite messy - fine, fine dust everywhere.

Cheers

Graeme

Avoid horizontal chases because they significantly weaken the wall, vertical chases don't. Also I wouldn't bother with conduit. You'll just need a wider chase. That white double insulated pvc wiring doesn't seem to break down and should be good for 50 years. By the time it needs replacing, if the house is still there, there'll probably be wireless light switches on the market.

Also, it might be easier to chase down and run the wires under the floor.