replace standard bulb holder with downlights

lillyput · 3 Apr 2021

hi guys

i'm wanting to replace the standard bulb holder in my bathroom for 3 downlights, with one of the downlights in the same place as the exisitng light.

what would be the best way of wiring this, can i link the 3 cables coming to the existing light to one the downlights and then connect this middle downlight to one on either side?

my main issue is with how to connect exisitng 3 cables to the downlight, i'm looking to research this and would appreciate some advice on this.

on a side note, the hole for the existing light is slightly bigger than the one required for the downlight, what is a good way of filling up a hole that is a couple of cms too big?

finally, i have a question about loads on an electrical circuit.....how exactly do i calculate what a safe load is at a particular part of a circuit. eg i am replacing 1 light with 3 leds, how do i calculate what a safe limit is?

thanks

ericmark · 3 Apr 2021

There are lighting junction boxes

designed for this job, remember even if the lights don't need an earth, the earth must be run to the light.

Taylortwocities · 3 Apr 2021

However, you will probably find that the existing lamp holder is screwed to a joist, or a solid wooden noggin. This will prevent you putting one of your downlights exactly there. So be prepared for some replastering work to hide the hole.
As above, use one of the purpose downlight junction boxes to Marshall all of the lighting cables. Mark and photograph all of the cables or you’ll need an electrician. re

lillyput said:
how exactly do i calculate what a safe load is at a particular part of a circuit. eg i am replacing 1 light with 3 leds, how do i calculate what a safe limit is?

Don’t worry about it. The lighting circuit will have been calculated for each light on it to be 100watts. Your three downlights (LEDs?) will probably total not much more than a tenth of the design current.

PS. What is above the ceiling? A loft, another room or another property? Do you have access up there?.

lillyput · 3 Apr 2021

thanks, noted about the junction box.

the ceiling is basically cladding attached to timber frame.

is there any disadvantage of bringing all the existing cables into the first downlight and then supplying the other 2 downlights via this first downlight, as opposed to daisychaining them?

yeah i figured my lights wouldn't have much of an effect on load, but it was more for my knowledge rather than this particular job!

plugwash · 3 Apr 2021

The issue is most downlights don't have much wiring room. Some only have room for a single cable, some have room for two. I highly doubt any downlight will have room for five cables to be properly and safely terminated.

lillyput · 4 Apr 2021

yep, just checked, mine has room for 2

Taylortwocities · 4 Apr 2021

So....

Taylortwocities said:
use one of the purpose downlight junction boxes to Marshall all of the lighting cables.

You may be able to run three separate cables from the junction box to the three lights.

I see from your picture that you are supplied with a bit of insulated terminal block (choc block). This junction must be inside a suitable enclosure. One of these will do it.
https://www.screwfix.com/p/chocbox-connector-box/54936

D4N1EL · 4 Apr 2021

I always buy down lights with a loop in loop out terminal. I don’t have them in my bathroom so I don’t know if they exist with the required IP rating.

Taylortwocities · 4 Apr 2021

D4N1EL said:
I always buy down lights with a loop in loop out terminal. I don’t have them in my bathroom so I don’t know if they exist with the required IP rating.

Yes, but there are none that support all of the connections enjoyed by a standard UK ceiling rose (loop in & out plus a switch connection). So an intermediate and appropriate junction box is still needed.

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replace standard bulb holder with downlights

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