How to cut a channel in an already fitted porcelain tile

[Milleniumaire]

Our bathroom has recently been tiled in 300 x 600 x 10mm porcelain tiles. For the first time I've encountered the difficulty of drilling through porcelain and even when using purpose made diamond drill bits, it still takes some time to get through!

Above our basin, there is an electric cable poking out of the wall (runs down the back of the plasterboard), which was installed for use with a LED mirror. The missus has now chosen her mirror, unfortunately the cable is in the wrong place!!! 3/4 of the back of the mirror will fit flush against the wall and the last 1/4 is where there is space for the cable and the connections to the mirror. Unfortunately for me, the cable needs to be moved 10cm to the right, I'm therefore considering cutting a narrow channel in the tile so the cable can be run to the required place.

I hate the fact I will have a nasty channel cut through the tiles, but I think this is unavoidable and there will always be a mirror in place to cover it up!

What is the best way to cut this channel?

I have plenty of different tools to try with:
- Fein multimaster - I suspect this would just take too long!
- Angle grinder (small). A possibility with the correct diamond cutting discs?
- Mini circular saw. Possibly not as controllable as the angle grinder, but I do have some diamond tipped discs already.

I would appreciate your thoughts/experience.

 

[Alec_t]

Dremel with a diamond cutting disc?

 

[Milleniumaire]

Dremel with a diamond cutting disc?

I always had the impression the Dremel was more of a craft tool. Would it really have the power to get through 10mm porcelain tiles?

 

[Alec_t]

10mm might be a struggle. I've only ever cut a shallow groove (3-4mm deep) in a ceramic tile of unknown quality.

 

[SFK]

I hate cutting and drilling porcelain.

Is mirror in a position to put spacers on screws between tiles and mirror to leave just enough space for the cable?

Sfk

 

[Milleniumaire]

I hate cutting and drilling porcelain.

Is mirror in a position to put spacers on screws between tiles and mirror to leave just enough space for the cable?

Sfk

Thanks for the suggestion Sfk.

I had considered trying to hold the mirror off the wall - just the thickness of the cable, by not screwing in the screws too far. I like the idea of using spacers better and I plan to give this a try before attempting to reposition the cable.

This is the mirror.

It has an LED around the edges, which we want to light up the wall, so I'm not sure exactly how holding it off the wall will affect the halo effect, possibly not at all. I've just ordered the mirror so whatever I do I will need to drill holes for the screws and I can always try to connect it up and mount it with spacers before deciding to ruin the tiles

 

[SFK]

Pleasure.

Nice mirror.

The spacers I used for a mirror with a heater pad behind were the rubber washers from taps.

Cheap, a good thickness. Will not rust. And I decided had a bit of rubbereriness to give some movement if needed.

Sfk

 

[johnny2007]

To connect the cable to the mirror you will need to open the mirror.
Once done this, drill a hole in the correct place of the back case of the mirror and use the rubber grommet in the original hole.
You will not need to move your cable.

 

[Milleniumaire]

To connect the cable to the mirror you will need to open the mirror.
Once done this, drill a hole in the correct place of the back case of the mirror and use the rubber grommet in the original hole.
You will not need to move your cable.

Interesting! My wife had suggested we may be able to "drill a hole in the back of the mirror to run the cable" and I told her not to be stupid! Maybe I'm the one being stupid! I guess when the mirror arrives I'll be able to see what is possible.

 

[johnny2007]

Done it lots of times.
Think about it: unless you have the mirror when you wire the bathroom, you wouldn't know where the entry point in the mirror is.
You could pass the cable on the left and entry point being on the right.
So, once you get the mirror, make your own entry point in the metal casing in the place more convenient for you.

 

[Milleniumaire]

Done it lots of times.
Think about it: unless you have the mirror when you wire the bathroom, you wouldn't know where the entry point in the mirror is.
You could pass the cable on the left and entry point being on the right.
So, once you get the mirror, make your own entry point in the metal casing in the place more convenient for you.

It would make more sense to me if the mirror had been designed to have a "void" across the whole of the back, rather than just to one side. Then it wouldn't matter where the cable was run. So, I had assumed there was a reason why the mirror was designed this way, possibly due to the demister pad that sits behind the mirror.

 

[Bodgedbuild]

Is this on an external wall? If not it might be better to get to it from the back of the wall, especially if it is a stud wall in which case you could knock a hole in the plasterboard to re-position the cable and pass it through a hole drilled through the tile?

 

[Milleniumaire]

Is this on an external wall? If not it might be better to get to it from the back of the wall, especially if it is a stud wall in which case you could knock a hole in the plasterboard to re-position the cable and pass it through a hole drilled through the tile?

Unfortunately it is a solid, external wall. I fed the cable down from above (loft space) myself, between the plasterboard and breezeblock, but it didn't take a direct route due to the plaster dabs and so would be difficult to feed it again without access to a hole at at the joint of the wall and the ceiling.

 

[Bodgedbuild]

Unfortunately it is a solid, external wall. I fed the cable down from above (loft space) myself, between the plasterboard and breezeblock, but it didn't take a direct route due to the plaster dabs and so would be difficult to feed it again without access to a hole at at the joint of the wall and the ceiling.

Could you break out a tile where the back of the mirror will be and then use a multi-tool to cut away the plaster/adhesive from the back of the tile you want to cut a groove in? Then you could clean the tile up and set it back with the cable behind it.

 

[Milleniumaire]

Could you break out a tile where the back of the mirror will be and then use a multi-tool to cut away the plaster/adhesive from the back of the tile you want to cut a groove in? Then you could clean the tile up and set it back with the cable behind it.

I do have some spare tiles, so I could remove one as the existing cable position and the required position are within the same 300mm x 600mm tile.

Once removed, it would be very easy to reposition the cable and fit a new, drilled tile.

However, that's quite a lot of work, with the risk of damaging surround tiles when trying to remove it (there's always some risk regardless of how careful one is).

It's a possibility, but given the mirror will always cover the tile, I'm not sure it is worth the hassle. My current thoughts are:

1. When the mirror arrives, determine if its possible to cut through the back of the mirror (probably invalidating the 10 year warranty) and run the cable that way.
2. If 1. is not possible, attempt to fit the mirror using spacers to allow the cable to run between the back of the mirror and the tiled surface.
3. If 2. is not possible, buy a Rubi viper turbo diamond cutting disc for my angle grinder and attempt to cut a channel in the porcelain tiles along which the cable can be run.
4. If 3. fails, possibly due to the hardness of the tiles (they are really, really hard!) or the tile breaks during my attempts to cut it, remove the tile, re-route the cable and replace a new tile.

I'm hoping to get the mirror tomorrow, so should be able to fit it over the weekend.