downlighters in plaster and lathe ceilings

[homeraway]

hi

looking for advice and guidance on fitting downlighters into plaster and lathe ceilings,

how best to cut holes and ensure ceiling integrity remains do we need to support lathes that are now separated etc. and what other considerations do we need to consider,

electrician will be doing final fix at some point but want to get holes drilled in place.

downlighters will need to be firerated as this is ground floor room ceilings, leading to upper floors.

thanks

 

[ree]

elec. forum will advise you best.

Actually cutting the hole can be the most straightforward part of installing DL's in plaster lath or any ceiling. There are a number of variables to take into account.

 

[bernardgreen]

Down lighters and lath and plaster are not good together.

Cutting the hole is not straight forward as the vibration in the lath as the saw cuts it invariably loosens some of the plaster from the lath.

Heat and scorching of the lath is another thing to be very careful about. A lath can smoulder for hours before it is noticed.

If you must have downlighters then you may need to re-inforce the ceiling before cutting the hole. Cut a piece of plywood with a hole in the centre that is about a 1/2 inch larger diameter than the diameter of the hole you are going to need in the ceiling. Drill a small hole in the centre of where the lamp will be fitted as a locator. Clean the top of the lath and plaster around where the hole will be cut and then fix the ply wood to the top of the ceiling using plaster or other gap filling adhesive and allow to dry. .

 

[RF Lighting]

You do not need fire rated down lighters. How much resistance to fire do you think your wooden ceiling provides?

 

[Taylortwocities]

You do not need fire rated down lighters. How much resistance to fire do you think your wooden ceiling provides?

Correct, the ceiling space of most buildings of that age are a veritable tinder box.

I usually bash away the laths to joist centre either side and fit a square of good old plasterboard. Do not do this if the Conservation Officer is about

 

[JohnW2]

I usually bash away the laths to joist centre either side and fit a square of good old plasterboard. Do not do this if the Conservation Officer is about

Be careful, though ... last time I 'bashed away' at laths on a ceiling, I ended up with much of the ceiling (well, the plaster) on my head!

Kind Regards, John

 

[homeraway]

Bernardgreen

thanks for the info, yeah i had thought of doing something similar to what you suggest but didnt want to go over board if it wasnt need, so will see how it goes.

 

[ericmark]

422.3.1 Except for equipment for which an appropriate product standard specifies requirements, a luminaire shall
be kept at an adequate distance from Combustible materials. Unless otherwise recommended by the manufacturer, a
small spotlight or projector shall be installed at the following minimum distance from combustible materials:
(i) Rating up to 100 W 0.5 m

In the main that means no down lighters in lath and plaster as the laths can burn. In fact unless the manufacturer says the lamp can be used in combustible material or within 9 inches of combustible material they can't be fitted in most domestic ceilings as the floor boards are often wood.

There is nothing to say using 5W LED lights is permitted it states up to 100W next category is 100 ~ 300W using common sense one realises that it's very unlikely that an LED type will be a problem. My copy of regulations is 2008 may be now it has been modified to allow LED lights to be fitted but I would say likely needs to be L2 type to stop being swapped to quartz halogen.

 

[JohnW2]

Deleted - how on earth did that quote get posted?

 

[JohnW2]

Unless otherwise recommended by the manufacturer, a small spotlight or projector shall be installed at the following minimum distance from combustible materials:
(i) Rating up to 100 W 0.5 m

In the main that means no down lighters in lath and plaster as the laths can burn....

We've been through this many times before, and I feel sure that regulation (and similar MIs) is talking about materials in front of a spotlight or projector bulb (i.e. having radiant heat/light falling on it).

Kind Regards, John

 

[Taylortwocities]

Indeed, and not a problem if they have the "F-Mark".
The main issue is a practical mechanical one of getting a substantial enough mounting for the fitting itself into a crumbling plaster crust..