Look before you leap has reared up and bitten me on the bum.

I've finished decorating the bedroom and the sitting room, and bought
replacement dimmers (nice brushed chrome ones) to replace the
knackered white plastic ones. Unfortunately, I didn't think to check
that the backboxes were suitable. So now I have to replace the 16mm
backboxes with 25mm ones.

Since both rooms are decorated and carpeted it's not just a question
of knocking a bloody great hole in the wall - I have to take a bit of
care. However, as long as I'm sensible I don't see any reason to
disturb the opening which should mean that whatever mess I make behind
won't matter.

However, are there any tips or tricks anyone can offer, or gotchas
that I might not have considered? I'm planning to drill some pilot
holes to approx. the correct depth and then use a hammer and chisel to
remove the rest. Is that a plan?

Thanks

Edward

On Tue, 9 Sep 2008 05:48:53 -0700 (PDT), wrote:

Look before you leap has reared up and bitten me on the bum.

I've finished decorating the bedroom and the sitting room, and bought
replacement dimmers (nice brushed chrome ones) to replace the
knackered white plastic ones. Unfortunately, I didn't think to check
that the backboxes were suitable. So now I have to replace the 16mm
backboxes with 25mm ones.

Since both rooms are decorated and carpeted it's not just a question
of knocking a bloody great hole in the wall - I have to take a bit of
care. However, as long as I'm sensible I don't see any reason to
disturb the opening which should mean that whatever mess I make behind
won't matter.

However, are there any tips or tricks anyone can offer, or gotchas
that I might not have considered? I'm planning to drill some pilot
holes to approx. the correct depth and then use a hammer and chisel to
remove the rest. Is that a plan?

Thanks

Edward

Sounds OK to me ....Obviously the first problem is getting the old box
out but you should manage that if you take your time and ease it out
gently after removing any plaster that might be in the knockouts .

I'm with you on drilling out to the required depth then chiselling out
the rest .....obviously you'll need to make sure the surrounding decor
and flooring is well protected from plaster and brick dust .At least
it's only another 9mm.

Stuart
P.S. You won't forget to isolate the supply will you ?

coughed up some electrons that declared:

Look before you leap has reared up and bitten me on the bum.

I've finished decorating the bedroom and the sitting room, and bought
replacement dimmers (nice brushed chrome ones) to replace the
knackered white plastic ones. Unfortunately, I didn't think to check
that the backboxes were suitable. So now I have to replace the 16mm
backboxes with 25mm ones.

Since both rooms are decorated and carpeted it's not just a question
of knocking a bloody great hole in the wall - I have to take a bit of
care. However, as long as I'm sensible I don't see any reason to
disturb the opening which should mean that whatever mess I make behind
won't matter.

However, are there any tips or tricks anyone can offer, or gotchas
that I might not have considered? I'm planning to drill some pilot
holes to approx. the correct depth and then use a hammer and chisel to
remove the rest. Is that a plan?

Thanks

Edward

Drill as much out as possible (lots of holes) to the right depth then gently
use a sharp masonry chisel to take out the rest would be my advice. But I
think you'll be fine as long as you don't go at it like a looney ;-
Dustsheet on the floor obviously, and any residual brick/plaster dust
generally hoovers up cleanly even off carpet. Make sure any paintwork that
may still be tacky is either not tacky or well protected.

Cheers

Tim

In article
,
wrote:
However, are there any tips or tricks anyone can offer, or gotchas
that I might not have considered? I'm planning to drill some pilot
holes to approx. the correct depth and then use a hammer and chisel to
remove the rest. Is that a plan?

I'd remove the old box by carefully folding it in on itself then cutting
with tinsnips etc to avoid damage to the surrounding plaster. Then once
it's out carefully slop some 4:1 PVA solution around the hole to try and
give some more strength to the plaster and leave to dry for a day or so
before commencing drilling. Also, use one of those universal bits and no
hammer action. Unless the bricks are so hard you have no choice.

--
*Elephants are the only mammals that can't jump *

Dave Plowman London SW
To e-mail, change noise into sound.

On Tue, 09 Sep 2008 14:45:28 +0100, Dave Plowman (News) wrote:

In article
,
wrote:
However, are there any tips or tricks anyone can offer, or gotchas
that I might not have considered? I'm planning to drill some pilot
holes to approx. the correct depth and then use a hammer and chisel to
remove the rest. Is that a plan?

You don't say what type of walls you have. I'm guessing they're not stud
cavity walls, as presumably you've had a good look at the existing box.

I'd remove the old box by carefully folding it in on itself then cutting
with tinsnips etc to avoid damage to the surrounding plaster.

I'd go with that, having replaced a couple of boxes myself, but I think
you'll be *extremely* lucky not to cause some damage to the plaster.

You may also find that the original box has a wirecut nail hammered into
the back as a fastening. That may well have rusted into the wall. No easy
way to get those out, it's (very careful) brute force and ignorance.

If you have breeze block walls it's relatively easy - if messy - to scratch
down to the required depth. If you have one, or know someone who owns one,
try a scutching hammer.

If you have brick or other similar hard walls, good luck, I'd look for
another type of dimmer. I have bitter memories from many years ago of
trying to set in a box where the internal walls were *extremely* hard
bricks. The hole in the wall was quite traumatising.......

--
Si Hoc Legere Scis Nimium Eruditionis Habes

the dot wanderer at tesco dot net

wrote:

Look before you leap has reared up and bitten me on the bum.

I've finished decorating the bedroom and the sitting room, and bought
replacement dimmers (nice brushed chrome ones) to replace the
knackered white plastic ones. Unfortunately, I didn't think to check
that the backboxes were suitable. So now I have to replace the 16mm
backboxes with 25mm ones.

Since both rooms are decorated and carpeted it's not just a question
of knocking a bloody great hole in the wall - I have to take a bit of
care. However, as long as I'm sensible I don't see any reason to
disturb the opening which should mean that whatever mess I make behind
won't matter.

However, are there any tips or tricks anyone can offer, or gotchas
that I might not have considered? I'm planning to drill some pilot
holes to approx. the correct depth and then use a hammer and chisel to
remove the rest. Is that a plan?

A lot depends on if you papered round the light switch or painted the wall.

If the former, you have a line that you can work to to prevent damage
outside of the light switch body. If the latter, then put some very low
tac tape around the switch before you remove it. Get a very thin bladed
screw driver and lean it towards the back box body so as to create a
small amount of distortion. Once you have done this on all 4 sides, take
an old screw driver and pick up on the distorted sides with the blade at
90 % to the back box side and lean it towards the centre of the back box
and collapse it towards the middle.

If, as someone said, there is a nail holding it to the wall, then you
will have to drill the head of the nail off. Start with a small HSS
twist drill (2.5 mm) and get a hole somewhere in the middle. Open this
hole up until the head drops off. The nail may be able to be removed
after you cut back for the new box. If it wont budge, cut the wall back
some more to make a cavity to bury it, then bend it over.

If you look at the back box you should be able to thread some thick
fencing wire through the holes at the bent over sides. Do this in an
equal way, so that if you pull one side, you can pull opposite at the
other side, this is so that the back box will not tilt over as it comes
out of the wall and rip off the plaster surrounding the cavity. If you
can only get to the top left on one side, go for the bottom right on the
other side. etc. The fencing wire should be twisted so that it secure to
the back box and have a loop at the other end. Make the twists are
longer than you think you will need. They can get pulled open if too
much force is put on them if they are too short.

Now find a small piece of wood and wrap it evenly with a clean cloth or
rag. You will be holding this against the wall to prevent any damage
caused by the pressure from the crow bar that you thread through the
loops, one at a time, to pull the box out of the wall. Put the bar
through the first loop, going across the box and place the end on the
block and pull. Then reverse everything and pull the box out again.
Now alternate the pulling so that you gain 1 mm at a time on both sides.

You might have to open the hole in the wall to get it to accept the new
back box.

I hope this works for you, it did for me a few years ago.

Dave

On 9 Sep, 13:48, wrote:
Look before you leap has reared up and bitten me on the bum.

I've finished decorating the bedroom and the sitting room, and bought
replacement dimmers (nice brushed chrome ones) to replace the
knackered white plastic ones. *Unfortunately, I didn't think to check
that the backboxes were suitable. *So now I have to replace the 16mm
backboxes with 25mm ones.

Since both rooms are decorated and carpeted it's not just a question
of knocking a bloody great hole in the wall - I have to take a bit of
care. *However, as long as I'm sensible I don't see any reason to
disturb the opening which should mean that whatever mess I make behind
won't matter.

However, are there any tips or tricks anyone can offer, or gotchas
that I might not have considered? *I'm planning to drill some pilot
holes to approx. the correct depth and then use a hammer and chisel to
remove the rest. *Is that a plan?

Thanks

Edward

If you have one, its an ideal job for the multimaster with the stiff
scraper blade - run that in around the edges to break the bond and
create a little room, and pull the box out. If it has a screw or nail
at the back, and it won't pull out, drill it out.

To get the extra depth, stitch drill completely around the outside (a
piece of wood the size of the box, drilled in the same pattern as a
template will help stop wander if needs be) and as much more as you
can be bothered, and then chip the rest out with a small, freshly
sharpened cold chisel.

On 9 Sep, 13:48, wrote:
Look before you leap has reared up and bitten me on the bum.

I've finished decorating the bedroom and the sitting room, and bought
replacement dimmers (nice brushed chrome ones) to replace the
knackered white plastic ones. *Unfortunately, I didn't think to check
that the backboxes were suitable. *So now I have to replace the 16mm
backboxes with 25mm ones.

Since both rooms are decorated and carpeted it's not just a question
of knocking a bloody great hole in the wall - I have to take a bit of
care. *However, as long as I'm sensible I don't see any reason to
disturb the opening which should mean that whatever mess I make behind
won't matter.

However, are there any tips or tricks anyone can offer, or gotchas
that I might not have considered? *I'm planning to drill some pilot
holes to approx. the correct depth and then use a hammer and chisel to
remove the rest. *Is that a plan?

Thanks to you all - what a great resource this is. I neglected to
mention that I've got four of these to do. What joy!

Edward

On Tue, 9 Sep 2008 05:48:53 -0700 (PDT), wrote:

Look before you leap has reared up and bitten me on the bum.

I've finished decorating the bedroom and the sitting room, and bought
replacement dimmers (nice brushed chrome ones) to replace the
knackered white plastic ones. Unfortunately, I didn't think to check
that the backboxes were suitable. So now I have to replace the 16mm
backboxes with 25mm ones.

Since both rooms are decorated and carpeted it's not just a question
of knocking a bloody great hole in the wall - I have to take a bit of
care. However, as long as I'm sensible I don't see any reason to
disturb the opening which should mean that whatever mess I make behind
won't matter.

However, are there any tips or tricks anyone can offer, or gotchas
that I might not have considered? I'm planning to drill some pilot
holes to approx. the correct depth and then use a hammer and chisel to
remove the rest. Is that a plan?

Thanks

Edward
ermm - you didn't mention if you already have cables going into the
back box, probably via the knockouts in the side/top.

All the suggestions above seem to not address the problem of getting
the back box out without damage to the cables! Bending the side of the
box inwards will just trap the cables, and it certainly won't pull
straight out of the hole with the cables in place.

Not that I have the answer, but would love to know how for when I
eventally get bitten by the same problem.
David

On Wed, 10 Sep 2008 19:38:55 +0100, davidm_uk wrote:

On Tue, 9 Sep 2008 05:48:53 -0700 (PDT), wrote:

Look before you leap has reared up and bitten me on the bum.

I've finished decorating the bedroom and the sitting room, and bought
replacement dimmers (nice brushed chrome ones) to replace the
knackered white plastic ones. Unfortunately, I didn't think to check
that the backboxes were suitable. So now I have to replace the 16mm
backboxes with 25mm ones.

Since both rooms are decorated and carpeted it's not just a question
of knocking a bloody great hole in the wall - I have to take a bit of
care. However, as long as I'm sensible I don't see any reason to
disturb the opening which should mean that whatever mess I make behind
won't matter.

However, are there any tips or tricks anyone can offer, or gotchas
that I might not have considered? I'm planning to drill some pilot
holes to approx. the correct depth and then use a hammer and chisel to
remove the rest. Is that a plan?

Thanks

Edward
ermm - you didn't mention if you already have cables going into the
back box, probably via the knockouts in the side/top.

All the suggestions above seem to not address the problem of getting
the back box out without damage to the cables! Bending the side of the
box inwards will just trap the cables, and it certainly won't pull
straight out of the hole with the cables in place.

Not that I have the answer, but would love to know how for when I
eventally get bitten by the same problem.
David

Fold the sides in a little way, without flattening them right down to the
back of the box, then it's a case of easing the bottom of the box out and
down over the cables. Almost impossible to do without at least a bit of
damage to the plaster. When I did it, I was left with two or three small
patches (upto an inch long and 1/4 to 3/8 at the widest) to make good with
filler.


--
Si Hoc Legere Scis Nimium Eruditionis Habes

the dot wanderer at tesco dot net

wrote:

However, are there any tips or tricks anyone can offer, or gotchas
that I might not have considered? I'm planning to drill some pilot

My approach would be to masking tape a dustbin liner under the cut out
in a form of hammock to catch the crud. Prise out the old box (drill
hole next to the fixings if required to allow it to be pulled free of
them if unscrewing etc is not an option). I would then stick a 40mm wide
chisel in the sds and plane down the back to depth. Only try this if
your drill has a decent speed control!

--
Cheers,

John.

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