Quick switch question

[down2earth]

Dear all,
Just started training to become an electrician, just done first week practical, made copious notes but not on the following: On a lighting circuit, when the feed comes into the switch first and then to the lamp, do i need to use 3 core to go from the switch to the lamp. Presumably the switched neutral and the live both go into the live bit of the lamp, if using 3 core, i guess the grey would go into the lamp neutral (with blue sheath) to complete the circuit. Apologies if this is really obvious but my brain hurts and I would appreciate some help

Thanks
Down2Earth

 

[MrTrance]

Im pretty sure you would use 1.5mm Twin & Earth, both live and neutrals become switch wires (neutral needs brown sleeving to represent it is live).

Then the neutral goes into the 'N' point on the ceiling rose, and the live goes to the loop section I think?

Can anyone confirm this?

TWIN & EARTH 1.5mm to the switch (from supply) and the same to the lamp.

 

[12345aob]

Dear all,
Just started training to become an electrician, just done first week practical, made copious notes but not on the following: On a lighting circuit, when the feed comes into the switch first and then to the lamp, do i need to use 3 core to go from the switch to the lamp. Presumably the switched neutral and the live both go into the live bit of the lamp, if using 3 core, i guess the grey would go into the lamp neutral (with blue sheath) to complete the circuit. Apologies if this is really obvious but my brain hurts and I would appreciate some help

Thanks
Down2Earth

you never switch a neutral, im not sure what your asking - I think you need some lighting diagrams and speak to the people you have worked with all week.

you would not need a 3core and earth as a bulb only needs a live and neutral(all cable must a carry an earth- usually..excluding tails,lv...)

are you taking the feeds to the roses or switches?

 

[down2earth]

the feed is coming in to the switch first, then to the lamp, whats confusing me is the lamp in question only has neutral and live (plus an earth connection), whereas the lamps we have been working on all week have the neutral, switch live and live blocks. I will try and post a picture to better explain what I'm on about.

Down2Earth

 

[Spudnik]

The lamps have a 4 way connector block, so that when a 3 plate is taken down, there is somewhere to terminate all the cables.

Live, Sw live, neutral and earth.

 

[bahco]

im a bit confused what your asking but il try and explain...

right the 2 main ways of wiring lighting

method 1 loop in & out of pendant
method 2 loop in and out of switch

method 1

from consumer unit in 1.5 t+e to first pendant, then 2 next etc etc... then from your pendant you take a 1.5 down to your switch... brown to common blue ( sleeved brown ) l1.

method 2 ( which i think your talking about )

from consumer unit to switch box, then from switch box to next box etc etc, then from switch box up to you pendant.

now because you have a permenant live neutral and earth at the switch, the 1.5 you take to the pendant goes to switch live neutral and earth.

kinda hard to explain really much easier when you can see it

hope this helps

 

[eskimo39]

Bahco's Method 1

The cable you see going to the Ls (Lightswitch) is just basic Twin & Earth, however because both sides will be live at some point you must sleeve the blue with some brown sleeving to indicate this.

For a lighting circuit you usually use 1.5mm2 or 1mm2 cable. In a lot of old installations the switch wire and feed was done in singles so you may find 2 red cables.

Method 2 is what I do now on installations. I have the Feed P/N/E inside the switch and then take a switch wire upto the lamp. Inside the switch itself I have the Feed Live (Phase) in the common, the Feed Neutral in a terminal block and the Feed CPC (Earth) in the backbox terminal with a jump lead to the switchplate if required. Now I have the Load Live in the switch L1 , the Load Neutral inside the terminal block and the load CPC with the Feed CPC. This cable is then run to the lamp in twin & earth (Live/Neutral & Earth).

I usually only use 3core when making 2way or intemediate switches or if installing an extractor fan with a permanent feed.

Hope this helps.

 

[down2earth]

I have hopefully attached a picture with the intended wiring. Live feed coming into the 'com' and the switched live going out from L1 to the lamp with the two neutrals connected in a block. Ignore the strange looking earth wires, this is just a mock up on a practice board in the garage. My question is, is this correct for a feed coming straight into a 1 way switch and then out to a lamp (in the loft in this case).
Thanks for any help

 

[Spudnik]

Spot on!

 

[old dog]

where are you training ?
college ?

 

[down2earth]

Training at New Career Skills, Chandlers Ford

 

[hughesy]

im a bit confused what your asking but il try and explain...

right the 2 main ways of wiring lighting

method 1 loop in & out of pendant
method 2 loop in and out of switch

method 1

from consumer unit in 1.5 t+e to first pendant, then 2 next etc etc... then from your pendant you take a 1.5 down to your switch... brown to common blue ( sleeved brown ) l1.

method 2 ( which i think your talking about )

from consumer unit to switch box, then from switch box to next box etc etc, then from switch box up to you pendant.

now because you have a permenant live neutral and earth at the switch, the 1.5 you take to the pendant goes to switch live neutral and earth.

kinda hard to explain really much easier when you can see it

hope this helps

Instead of sleeving the neutral why dont you use twin brown+earth and lighting circuits can also be wired in 1.omm on a 6 or 10 amp mcb.

 

[telectrix]

as your pic shows, you are permanently connecting the neuteral to the lamp and breaking the live with the switch, when wiring like this, the centre terminal block in the ceiling rose is not used. just as eskimo says. this is method 2

 

[ezzzekiel]

I have hopefully attached a picture
View attachment 153

a picture paints a thousand words - good job

 

[down2earth]

Thanks for all the replies, forgotten i posted this but all useful.

Down2earth