Getting across ceiling joists from below - tricks of the trade.

FatAlan · May 30, 2019

In the day and age of ..how many downlights can we get into one house, I'm intrigued to know what tricks / techniques folks use to install multiple downlights into an existing ceiling in replacement of a central pendant. In particular, once having located the joists, how do you get the cables across or through the joists with minimal damage to the ceiling? Is it a case of just cutting an access hole in the ceiling across the bottom of the joist so that you can see both sides with enough space to drill a hole (building regs compliant). Does anyone cut small notches and protect with steel plates for instance?

Dustydazzler · May 30, 2019

If possible wire from above by lifting or cutting floorboards or via loft space / eave voids

I’m not a fan of ‘notching’

You can cut holes and pop the circular cut out back in

Baddegg · May 30, 2019

With you dusty, if I can’t get the floors above up them it’s cut neat round holes (sharp holesaw) and timber across and reinstate the cutouts, bit of fine filler and all’s good

Edit.....unless it’s artex then it ain’t getting done..

Squid · May 30, 2019

Do the job properly,

joking apart what access do you have from above, how many lights, in what direction are the joists layed out in etc etc?

[ElectriciansForums.net] Getting across ceiling joists from below - tricks of the trade.

Wilko · May 30, 2019

Hi Al, at risk of revealing bias here, but notches are for Plumbers. I think I could run a C&G course in upside down temporary mini golf course design and construction.

Leeroy · May 30, 2019

New builds nearly always cut holes in ceiling and drill through joists them patch back in with batten and the plasterboard that has been cut .

Notching underneath joists is not permitted .

Rpa07 · May 30, 2019

I always say “you gotta break eggs to make an omelette” - once I’ve explained this 3 or 4 times they let me holesaw loads of holes (I use 100mm so I can get my arm in there) to drill your joists.
It’s the careful planning of where the joists are so you can do as few holes as possible to route your cables.
It’s music to my ears when they state that the ceiling will be skimmed!

Dustydazzler · May 30, 2019

Baddegg said:
With you dusty, if I can’t get the floors above up them it’s cut neat round holes (sharp holesaw) and timber across and reinstate the cutouts, bit of fine filler and all’s good

Edit.....unless it’s artex then it ain’t getting done..

Artex is horrible to repair

I just done a small job a kitchen where the electrical job took about 25 mins after cutting a small hatch in the ceiling

The making good and applying a fresh splodge of artex to the new bit of boardi put in took about 3.5 hours in an attempt to make it look like the ceiling hadn’t been cut

Dave5678 · May 30, 2019

FatAlan said:
Does anyone cut small notches and protect with steel plates for instance?

I'm pretty sure the building regs say that you can only put a notch in the top side of a joist, not the bottom, in the region that is between 0.07 and 0.25 of the span. Electrical regs then require you to protect the cables against penetration. Better to route your cables in the zone where you can drill holes through the joists.

FatAlan · May 30, 2019

Cheers folks. Just checking I wasn’t missing a trick. I like the omelet scenario

Squid · May 30, 2019

Dustydazzler said:
Artex is horrible to repair

Who the hell has Artex on the ceiling I suppose the ones with woodchip on the walls......

Gary latto · May 30, 2019

One board up in opposite direct to joists and up and down each bay bit more cable but saves loads of time

Shoei · May 30, 2019

Seeing a lot of this kind of thing lately, doesn't work for me but someone must like it..

Dustydazzler · May 30, 2019

Oh my

That is hideous

Midwest · May 31, 2019

I did the whole thing, even a complete narrow section of plasterboard down, then reinstate the board. I’d always have the customer pay to have it plastered & decorated afterwards, unless it was only a couple.