fitting spotlights into 120 year old lath and plaster ceilin

[sarahw]

The ceiling is prety intact and I'd like to just fit recessed spotlights into the existing ceiling. Is this likely to cause problems with lath and plaster? I had to drop one ceiling, so did a test drilling a 2mm hle and it seemed to work well and didn't break away. Access is easy as above it is theloft

Advice needed please

 

[skenk]

What size holes do you need to cut? Are they for halogen downlights?

It's not easy to get good downlight cuts in lathe and plaster. I find a holesaw is only any good for getting the plaster out then you have to saw through the lathe's individually due to the disturbance the holesaw causes on the lathes and the fragility of a lathe and plaster ceiling. It's difficult to get a good hole then fit the lights and still be left with a sound surrounding ceiling.

Have never tried with easy access to above but could be worth trying to start by drilling the holes from above then when you are through the lathe use the hole from the mandrel drill as a guide and finish off from below.

Presence/absence of insulation, thermal and environmental factors should be taken into account. . . part p? etc

 

[sarahw]

Hi,

Wen I wrote I dd a test 2mm hole, I meant to type 72mm. With a hig speed drill and a holesaw and lots of patience, I got through the laths cleanly. I could drop bnding coat onto the laths from above which wold help to reinforce them when teh hole's been cut

Part P - it's a hallwy, so I believe my work is outside of the regs as long as I follow IEE standards of wiring...?

 

[Chri5]

Why not bond the laths before drilling since the issue is the amount of movement the hole saw will make against the laths.

That should reduce the potential problem with the drill breaking the laths away from the 120 year old plaster (with horse hair ?).

Minor alteration to existing circuit can be covered via a MWC and doesn't require LABC / scheme notification.

 

[holmslaw]

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[skenk]

Dont see why you can't use f-marked fittings

 

[holmslaw]

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[Chri5]

If low energy fittings are used, bright 5w led or CFT then there shouldn't be an issue with heat.

 

[ban-all-sheds]

The ceiling is prety intact and I'd like to just fit recessed spotlights into the existing ceiling. Is this likely to cause problems with lath and plaster?

No, but it will cause problems with the effective illumination of the hallway if you use small recessed lights, which you seem to be planning to do.

 

[ban-all-sheds]

If low energy fittings are used, bright 5w led or CFT then there shouldn't be an issue with heat.

If that's actually necessary to avoid a fire risk then you'd have to use luminaires which could only take low energy lamps, otherwise there'd be a risk in the future of someone fitting incandescent ones.

 

[skenk]

Dont see why you can't use f-marked fittings

Because the f mark means - suitable for mounting in or on a flammable surface that will not be damaged by a temperature of up to 80c. The key word being "surface", the back (top) and side temperatures of the fitting are not part of the classification or the temperature rise limit of 80c.

Also fire hoods and intumescent downlighters do not provide a solution either.

So it's not possible within the wiring regs to fit any type of halogen downlight fitting to, say, wooden panelling? I'm no fire expert but I highly doubt that wood is affected by a temperature of 80c.

 

[holmslaw]

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[LiamPope]

I've also read for the F mark: 'Suitable for mounting to normally combustible materials', and 'the mounting surface [of the light fitting] will not exceed 90 degrees'. Anyone know what standard the test for F marking is defined in?

I think it would be reasonable to include in the definition of a fitting's mounting surface, any part of its surface that would come into contact with that in/on which it is mounted. IMHO it would seem a strange interpretation of the above (or Holmslaw's) definitions if you were to conclude an F marked fitting was not suitable for mounting in a lath and plaster ceiling, or a sheet of mdf, etc etc, as it would rather seem such a determination is the whole point of the test for F marking. What, Holmslaw, do you think an F marked fitting can be fitted to? Only a non combustible substrate with a thin wood veneer, such that the wood is only on the front surface?

There must be countless F marked (and probably plenty of non-F marked ) light fittings installed in lath and plaster or timber all over the place. Perhaps I might ask a few manufacturers what their products' F markings really imply...

Liam

 

[holmslaw]

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[skenk]

So it's not possible within the wiring regs to fit any type of halogen downlight fitting to, say, wooden panelling?

It is not permissable to fit any type, they would have to be F type.

Clearly you have misunderstood me, you admit that F-marked can be installed in wooden panelling.

I'm no fire expert but I highly doubt that wood is affected by a temperature of 80c.

I agree it would'nt catch fire. But the point you're missing is, the F type fitting temp limit is 80c on the mounting surface. The temp limit does not apply to the rest of the fitting.

Eh?

So you can fit f-marked in wooden panelling but not in lathe and plaster ceiling, oh no wait there might be some wood shavings so thats why you can't install them . . . . . you're talkin a lot of nonsense mate.