Drill size for lighting cable

[Echo the husky]

It's far easier to repair plaster damage than brick damage. Here is what 2 stupid sky installers did here. One bit of damage wasn't enough so they drilled another hole in the same fashion when sky+ was installed. There is more damage around the house where multiroom was installed, this time the corner of the brick is missing. I don't watch TV so all the cables are removed. But I will have to replace the bricks now. It's a job I don't enjoy doing.


I also try to fit conduit in the walls to protect the cables where practical, though it often isn't, and drilling a large hole for a 1mm cable is a lot of work. When I do, I use a 22MM core drill to cut the hole.

Leaving the cable sticking out the wall is fine, the tape should be used only for keeping the damp out of the end of the cable. The cable must not be connected the other end.

 

[Taylortwocities]

Leave the end of the cable dangling. I am assuming that you are not going to connect up the other end!

 

[Jupiter01]

Thanks guys, the cable will definitely not be Live.
One final question - is there a limit to the length of a lighting circuit? I have a circuit (trip switch on consumer unit) devted to exterior lighting. There will be 14 lights on this but the length of total cable could be around 35 metres.

 

[Taylortwocities]

is there a limit to the length of a lighting circuit?

It depends on the length of the cable, the thickness of the cable, the voltage and the earth fault loop impedance.

 

[Jupiter01]

This will be 1.5mm T&E. The RCBO at the consumer unit can be whatever we need it to be.

 

[Echo the husky]

is there a limit to the length of a lighting circuit?

It depends on the length of the cable, the thickness of the cable, the voltage and the earth fault loop impedance.

What about the load connected?

 

[Jupiter01]

There will be 7 led downlights, 4 up and down lighters, 2 flood lights and 3 bulkheads.

 

[ban-all-sheds]

Is a conduit necessary? How do most people pass cables through a cavity?

Often with a fair bit of cursing - it's amazing how hard it can be to find the other hole by poking cable through. Conduit, being rigid, is easier to poke about with. If you don't want to use it, then once you've got the holes drilled, push a bit through both, then tie string to the end and pull it back through. Or tape the cable to it.

Also, since I am first fixing at the moment and not connecting the exterior light, is it okay to leave the cable dangling out (exposed to the weather) with some insulation tape on the end?

When installed, will the cable enter the rear of the light, or will it always be exposed?

 

[winston1]

This will be 1.5mm T&E. The RCBO at the consumer unit can be whatever we need it to be.

Use 1.0mm, it's quite adequate, cheaper, and saves the worlds copper resources.

 

[Echo the husky]

Use 1.0mm, it's quite adequate, cheaper, and saves the worlds copper resources.

The USA seems to be wasting a lot of copper with their 120V system.

 

[Jupiter01]

so will this circuit be okay over approx 35 metres and with the lighting I've specified? Thanks

 

[Jupiter01]

the cable will enter tear of lights and not be exposed. In response to earlier question.

 

[ban-all-sheds]

so will this circuit be okay over approx 35 metres and with the lighting I've specified? Thanks

• http://www.google.co.uk/search?q=cable+installation+methods+17th+edition
  
  
• [wiki]Electrics%3AMCBtoCable[/wiki]
  
  
• http://www.tlc-direct.co.uk/Book/4.3.1.htm
  
  
• http://www.tlc-direct.co.uk/Book/4.3.11.htm
  
  
• http://www.tlc-direct.co.uk/Book/5.3.1.htm
  
  
• http://web.archive.org/web/20070327014113/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html <- Specify 2-core cable and PVC, even if that is not what you are using or it will make invalid assumptions.
  
  
• http://www.batt.co.uk/upload/files/4d5.pdf
  
  The references above which are in italics are out of date. The principles are still valid, and you can absolutely learn valid things from them, but you will need to refer to the latest edition of the Wiring Regulations to get the correct data.

 

[stillp]

so will this circuit be okay over approx 35 metres and with the lighting I've specified? Thanks

The format of the lights doesn't matter. You haven't told us the total wattage.

 

[Jupiter01]

by wattage do you mean bulb wattage? Or does this provide a good indication?