wiring for downlight connection above ceiling

[catnipsta]

Hi

I am planning to install downlights in my lounge ceiling, but I am wondering what the best method is for wiring the lights together. The problem is that the various joists above the ceiling seems to be a big obstacle, since I cannot locate any gaps between the ceiling and the flooring on the above floor.

Do I have to cut a large enough holes in the ceiling so that I can drill sufficient holes in the joist to thread and fish the wires through ? Or do I have to access this space by removing the flooring from the floor above?

many thanks in advance

 

[plugwash]

generally removing/refixing floorboards is easier than doing the smae with the ceiling

and you have a much easier/safer position to drill from

ofc if you have some form of permanent (ie hard to remove without destroying) flooring upstairs then cutting up the ceiling may be preferable

 

[TexMex]

Whichever way you gain access, you should endevour to make your holes as close to the top edge of the joists as is practical. The closer they are to the bottom, the more it weekens the joists.

From the floorboards is the norm. Even if you make a right pigs ear of it, patching up floorboards and covering the resultant mess with carpet, is a lot easier than making good the ceiling. (unless you're a plasterer of course )

 

[catnipsta]

I have decided to access the space from the upper flooring since there appears to be several joists that needs drilling between the lights - and the need to cut several access holes in order to do so.

Thanks plugwash for the advice in where to make the holes.

Is it the case that my house (Barratt's homes - built late 80's (( ) has been built with no spaces to allow for "fishing & threading" the wiring? What do people do who live in modern single floor flats? Is the only solution cutting access holes into the ceiling ?

 

[dingbat]

Whichever way you gain access, you should endevour to make your holes as close to the top edge of the joists as is practical. The closer they are to the bottom, the more it weekens the joists.

Whoa boy! Yes, if you're concerned about bending moments what you say is not without some validity but with both the loading factors and material factors applied this is unlikely to be an issue. And holes at the top near span ends will reduce shear strength anyway.

What is more important to consider is that wherever holes are drilled through joists they should at sufficient depth that penetration by screws/nails from above or below is avoided. The recommendation is for holes to be drilled on the joist centreline in a zone between 0.25 and 0.4 x the span. Holes to be no greater than 0.25 x joist depth and holes in the same joist should be at least three diameters apart.

 

[dingbat]

Is it the case that my house (Barratt's homes - built late 80's (( ) has been built with no spaces to allow for "fishing & threading" the wiring? What do people do who live in modern single floor flats? Is the only solution cutting access holes into the ceiling ?

Some modern composite joists systems have 'knockouts' which can be removed as required but even then it is normal to only remove what you need. Your cables will be routed by the most economic means to provide the lighting to the original specification and there is no need whatsoever to try and guess what a future owner might want to do. And yes, in many flats the only access will be via the ceiling.

Downlighters? A pain in the backside. Make sure you plan exactly where you want them and provide suitable fire protection.

 

[securespark]

Agreed Dingbat. I am doing my very last downlighter install tomorrow. Never again!

Yipee, I'm freeeeeeeeee........!

 

[ban-all-sheds]

Downlighters? A pain in the backside. Make sure you plan exactly where you want them and provide suitable fire protection.

I like them.

I know they're a pain to fit, and I know all about the fire proofing, short lamp life, difficulty of lamp replacement, cost of lamps yadda yadda yadda, but I can't abide things that dangle from the ceiling. In the context of an ordinary house I have never, in my whole life, seen any pendant fitting that I liked.

Recessed downlighters and unobtrusive wall-mounted uplighters for me.

 

[treacleman]

But aren't those new(ish) low energy pendants so adorable? a lovely dangling white stick of light which can only be replaced by a lovely dangling white stick of light!
<switches off sarcasm mode>