Ceiling spots - threading cables

[Ro]

Hi,

I am planning to fit about 6 12v ceiling spot lights in an apartment living room. There's an existing ceiling rose, that I'll be getting rid of, and as such I plan to wire the transformer to the supply to the existing light. My only concern is running the cables to the spotlights. I expect there will be joists in the way, and I don't know if there will be any space between the top of the joists and the floor of the next apartment. It's an old custom built block, about 20 years old.

I had read about people having to cut out portions of plaster board around joists to then cut a hole in a joist.

Is this difficult?

How would I patch up the hole again, so that it would not be noticible when painted?

Any suggestions would be very welcome.

Thanks,

Ro

[Biscuit]

To avoid using transformers & line voltage drop, look at the 240v lamps.

[The Natural Philosopher]

If you want to do the best job, consider ripping the whole ceiling down and wiring it, then replacing the plssterboard and skimming.

It is probably a less ardous job than threading cables around and drilling joists with righ nagled drills etc.

[Dave Plowman]

I'd say this is unlikely - the floor and ceiling will share the same joists.

[Ro]

Thanks for the suggestions.

The floor above is concrete, so it's not dependent on the ceiling joists for support. I reckon it might be possible that there would be space between it and the ceiling to thread wires (I hope!).

If I did need to make a few extra holes in the ceiling to negotiate the joists, is there a simple way to fill them without having to replaster the ceiling?

Thanks,

Ro

[Howie]

|Thanks for the suggestions. | |The floor above is concrete, so it's not dependent on the ceiling joists |for support. I reckon it might be possible that there would be space |between it and the ceiling to thread wires (I hope!). | |If I did need to make a few extra holes in the ceiling to negotiate the |joists, is there a simple way to fill them without having to replaster the |ceiling? | (don't top-post)

This is what I did...

Near the existing light cable, I made a hole big enough to get my hand through (approx 4 inches, mine was square and I only cut 3 sides to make a sort of hinge). Inside the ceiling now, I fixed the transformer to the nearest joist using the hole for access, and wired it into the existing feed. Then, inside the hole, I measured the space to the joist I wanted to hop under first. Repeat this measurement on the underside of the ceiling and, from below, cut (stanley knife) the plasterboard across the joist. Pull the wire through, under the joist, tape it the end of a coathanger, and push it along to the next joist. Now you know the distance between joists you can cut small feed trenches exactly where you want, and feed the low-voltage cable around/across the ceiling. As you progress, the holes you make for each downlighter help with the feeding process too. I ended up with a series of holes which were each the size of a small nail-file, - easy to fill with polyfilla. You can fill the hinged acess hole by pulling it down slightly higher than flush, gluing, and then 2 thin layers of polyfilla or plaster top-coat, sanding in-between, before painting.

Might be a bit of a heath-robinson solution, but it took me less than a day for 12 downlighters and nobody can see anythng but a smooth ceiling. The low voltage can easily have a 2" bit of filler over it without risking fire or damage.

Hope it helps a bit.

[The Natural Philosopher]

Yes. If you cut the holse carefully, you can refit the cuit bits with something tacky or even bonding plaster, and set em back a bit, and then skim the surface with PolySkim.

You will need to repaint tho.

[Ro]

Thanks for the suggestions. I like the idea of the small cuts at the joists, and covering with polyfilla. I had visions of having to cut huge chunks out of the ceiling to drill joists.

With a bit of luck, I'll be able to thread the wires around with hitting too many joists. It's a pretty small room, and only 6 lights.

Will keep you posted.

Ro

[Chippy]

Not so in more modern developments, where the joists are suspended from the concrete above via buffers designed to reduce the transmission of impact noise.

I've installed lighting in a couple of these flats using a steel tape measure to get a string through the 15 - 20mm gap above the joists, then using the string to draw the cable.

I also suspended the transformers, using strong rubber bands, in order to reduce any buzzing.

[The Natural Philosopher]

Ive done this more than once. Cut out small channels over the joists, notched em, and threaded wires over the plasterboard and under the nothced joists. Tack with a p-clip and bodge the holes away later.

Its nopt too bad.

[Ro]

That's interesting. I was hoping there would be a gap between the top of the joists and the floor above. One slight concern is that this is a not so new building. it looks about 10-15 years old, but is actually 23 years old.

Anyhow, with all the suggestions, I should find a method that works. I haven't actually moved in yes, and so can only speculate.

We'll see

Ro

[The Natural Philosopher]

To avoid replacing bulbs on a weekly basis, look at the LV versions.

I have been in this house now for two years since first lighhts went on.

In that time I have replaced COUNTLESS mains bulbs, but the only LV bulbs that have gone

after a couole of years of CONTINUOUS DAILY USE of at least 4 hours per day, are the half ones that came with a couple of rail units.

I got about 50 LV 50W lamps from Newey and Eyre, AND NONE HAVE GONE IN TWO YEARS. They are used in all the corridoors and bathrooms and the kitchen, so they are not just 'occasional use'..

Friends who have mains units on average seem to have one a week going in winter - about 5% failure. That implies the average weekly life is no more than 20 weeks of heavy duty.

I seem to be getting better than 200 weeks average. My bulbs cost about

2 quid each. The mains are a bit cheaper, but overall the savings are there on LV.

I had one supposedly thermally protected toroidal transformer go after a few weeks. None of the electronic transformers have gone.

[Dave Plowman]

You must have something weird with your supply. I've got probably more lighting than average much of it mains bulbs (RO 80, etc) and find they pretty well always give their design life.

[The Natural Philosopher]

Well I don't know what service life is, but nearly all of my 40W candle bulbs have been replaced in that period. Say 90% The cheapo LV ones have had 50% failing two years. The Newey ones have not failed at all. All the 60W standard bayonets have gone in the two years. So it would seem that the average life of a mains incandescent bulb is a tad less than a year under heavy use, but the better LV spots are looking more like three years, with a mean life of 2 years on cheapo LV. It MAY be that the cheapo ones are on electronic transformers, that came with them, of a higher voltage output than my normal Newey toroids. With which the non dimmed units are equipped.

>

[Dave Plowman]

Reckoned to be 1000 hours for a gls type.

Ah - say no more. Candle lamps seen to go straight out of the box, sometimes.

My RO80 types of which I've many seem to have the same sort of life as a gls, and I've not had LV types for long enough to form an opinion. But they are looking good. I'd happily replace all the RO 80 ones with LV, but of course I'd like the smaller fittings too, and that means replacing plaster, etc. I've also got several PAR 38 fittings, and some of those have 25 year old bulbs...

[Fraser]

Hi All,

I've got some 40W screw-in spots in a 4-way cluster in the kitchen, the kind with the screw diameter about half that of an "average" bulb. I think the best record for any bulb's life is six months, and it is pretty much guaranteed that at least one is out at any time. I tried switching to a dimmer thinking that lowering the light level might extend life, but no joy.

Yet, in the lounge, from the same supply (and fuse), is a 5-way cluster of

40W candle bulbs that haven't blown ever in the three years I've lived here. Usage is pretty much the same for both rooms. From the same double dimmer switch are another two candle bulbs on the wall that have average lives. I'm thinking about submitting the ceiling ones to medical science due to their longevity. Not as good as this one though: ideas on the kitchen ones? It's bankrupting me, and it's also a PITA replacing them due to their height/location. Other bulbs in the flat seem fine.

F./

[Dave Liquorice]

Do the maths on how long the cluster will have been on in those 6 months. 5 1/2hrs day = 1000hrs about normal bulb life...

Why do these fail rather than the candles? Probably excessive heat build up in the fitting. I expect they are fairly well enclosed in plastic around the back of the bulb.

Do you run them dimmed though? Another cause of bulb failure is vibration, is there any visible shaking of the filament (watch one of the light patches) when someone moves about in the rooom above, bear in mind children are very heavy footed. B-)

Don't buy your bulbs from a DIY store or supermarket. Find an electrical wholesaler and buy 10 or so at a time at roughly 50% the "shop price".

[norm]

Those screw in bulbs are the work of the devil. I'm always replacing them at my mother in laws flat. I suspect the failure rate has as much to do with the fitting as anything else. I believe that ventilation is important to reduce the effects of thermal cyling on the bit of the bulb where the glass is sealed / joins the metal bit. If the thing gets too hot repeatedly the seal goes, air gets in and kappow !

I'd be looking to replace the whole fitting and go for a different type of bulb. They're crap. And not cheap crap either.

[Dave Plowman]

The glass bit is sealed. The cap - whether ES or BC is simply glued on to that.

[Andrew Gabriel]

IKEA have started doing Compact fluorescent versions of these. They are stated as 25W equivalent, but are flood lamps rather than spot lamps (which for general lighting might be better). They start off very dim though -- full brightness in around a minute probably (don't have one here to time it). You would have to remove the dimmer of course.