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Discuss 1mm or 1.5mm for all internal light runs ? in the Electrical Forum area at ElectriciansForums.net

LukeD

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Anyone only ever use 1mm T&E for domestic lighting (Average 3 bed etc) Or are you using 1 mm &1.4mm for drops and runs etc ? Now that 90% of stuff is LED bulbs etc . Not thinking for exterior light etc .
 
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littlespark

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Typo on the post? 1.4??

1.5 normally, but will use 1.00mm if just doing links between downlights on the same switch. That sort of thing.
 

Dave OCD

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Realistically 1mm is more than enough , 1.5mm in domestic lighting is just a waste of money and copper. Although I do like 1.5mm for surface clipped cables in garages or outbuildings, just nicer and easier to get looking spot on.
 

littlespark

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1.00 would be fine, if it wasn’t for 2 feet of insulation sitting on top of it, and it’s the main feed cable from the CU.

Why I use two sizes? I bought 1.00 in error, used it for some downlights etc, but next visit to wholesalers, I got 1.5.
Using both drums up now.
 

Pete999

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1.00 would be fine, if it wasn’t for 2 feet of insulation sitting on top of it, and it’s the main feed cable from the CU.

Why I use two sizes? I bought 1.00 in error, used it for some downlights etc, but next visit to wholesalers, I got 1.5.
Using both drums up now.
So your mistake then? can't see how you can try and convert people due to a mistake on your part.
 

littlespark

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Not trying to convert anybody… just saying what I do.

the original question was “anyone ONLY ever use 1mm?”
I was saying no, I use both.
 

SJD

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For a small property (e.g. 3-bed semi-sized) then I normally use only 1mm2.

For a larger property (e.g. 3 storey mansion with longer cable runs) I typically use 1.5mm2 for the feed, which is nowadays going from CU to switch to switch. Then 1mm2 from the switches to lighting points, which will often be a string of downlights.

Not a problem to have reels of both, in fact I make sure I've got supplies of both.
 
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longer runs on 3 or 4 storey houses use 1.5 the rest 1mm twin n earth; 1mm 3core for all switch wires to leave earth and neutral in each back box.
 
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I used to like using 1mm for the simple reason of pulling through conduit on switch drops etc on rewires.
with needing neutral in back boxes now im finding got dig the 16mm b/boxes out and put 25mm ones in especially 2 way switching and 2 or 3 gang switches.
 
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I think the norm used to be 1mm for downstairs lights and 1.5mm for upstairs to account for possible insulation which sometimes people put masses of it...

Personally I just use 1.5mm, for the simple reason that I only have to carry 2 reals, 1.5mm T+E and 1.5mm 3core and Earth rather than 4 reals.. I agree its a bit of a waste of copper but also prefer working with 1.5mm as when it goes into a screw terminal its less likely to break off... But thats just personal preference, I might change if copper prices keep going the way they are though..
 

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