Light switch

All electrical lighting questions in here please. Including outside lighting and light switch / dimmer questions.

Moderator: Moderators

User avatar
mole81
Senior Member
Posts: 785
Joined: Mon Mar 07, 2011 2:18 pm
Has thanked: 33 times
Been thanked: 3 times

Light switch

Post by mole81 » Sat Oct 20, 2018 3:41 pm

Changed a simple light switch earlier, black cable was common and L1 red, previously doing this I'm sure red should be common? Or should I shut up now ha! Image

Sent from my SM-G930F using Tapatalk
User avatar
wine~o
Senior Member
Posts: 24624
Joined: Sat Jan 10, 2009 3:49 pm
Location: hants/dorset border
Has thanked: 1315 times
Been thanked: 3618 times

Re: Light switch

Post by wine~o » Sat Oct 20, 2018 4:30 pm

Convention says that the red (permanent live) goes to com. However the switch itself neither knows nor cares whether red is in com or L1.

It just sits there being a switch.
Verwood Handyman

Verwood Handyman


___________________________________________________________________

If you feel you have benefited from the Free advice given on the Forum, Please consider making a donation to UHM's Nominated charity, read all about it and donate here :

http://www.donnasdreamhouse.co.uk
User avatar
someone-else
Senior Member
Posts: 8809
Joined: Sat Sep 01, 2012 6:03 pm
Has thanked: 41 times
Been thanked: 1487 times

Re: Light switch

Post by someone-else » Sat Oct 20, 2018 5:44 pm

It really depends on how whoever wired it in the first place chose to wire it, the electricity is not going to complain about the colour of the insulation.
As wine~O suggests, ideally the red should be permanent live and the black should be switched live (With a red marker) But we don't live in an ideal world.
Fret not, a forum is a collection of opinions. Above, are mine.

Which is correct? Metre or Meter? Click the link to find out more.

Working on anything electrical? have you got a multi meter? why not? Would you hit a nail with a shoe?

If gloom had a voice, it would be me. :mrgreen:

:idea1: How to post a picture on this forum Click here
User avatar
mole81
Senior Member
Posts: 785
Joined: Mon Mar 07, 2011 2:18 pm
Has thanked: 33 times
Been thanked: 3 times

Re: Light switch

Post by mole81 » Sun Oct 21, 2018 5:55 am

Thanks for the replies, what would happen if the red actually was the permanent live and these were swapped?

Sent from my SM-G930F using Tapatalk
User avatar
someone-else
Senior Member
Posts: 8809
Joined: Sat Sep 01, 2012 6:03 pm
Has thanked: 41 times
Been thanked: 1487 times

Re: Light switch

Post by someone-else » Sun Oct 21, 2018 7:17 am

mole81 wrote:what would happen if the red actually was the permanent live and these were swapped?
As wine~O and I said
wine~o wrote: However the switch itself neither knows nor cares whether red is in com or L1.

It just sits there being a switch.
someone-else wrote: the electricity is not going to complain about the colour of the insulation.
The other thing to "wonder about" is:

Is the red permanent live? it may be that the black is permanent live, unless it is tested, or traced back to the other end, no one (apart from whoever installed it) will ever know.
But it's not a case of "well it works so it must be ok" it is a case of, it's wired correctly, it is using the correct size cable, and it works (But it does not have "coloured tags" to identify which is the live)
Last edited by someone-else on Sun Oct 21, 2018 7:21 am, edited 1 time in total.
These users thanked the author someone-else for the post:
mole81
Rating: 7.14%
Fret not, a forum is a collection of opinions. Above, are mine.

Which is correct? Metre or Meter? Click the link to find out more.

Working on anything electrical? have you got a multi meter? why not? Would you hit a nail with a shoe?

If gloom had a voice, it would be me. :mrgreen:

:idea1: How to post a picture on this forum Click here
User avatar
mole81
Senior Member
Posts: 785
Joined: Mon Mar 07, 2011 2:18 pm
Has thanked: 33 times
Been thanked: 3 times

Re: Light switch

Post by mole81 » Sun Oct 21, 2018 7:20 am

someone-else wrote:
mole81 wrote:what would happen if the red actually was the permanent live and these were swapped?
As wine~O and I said
wine~o wrote: However the switch itself neither knows nor cares whether red is in com or L1.

It just sits there being a switch.
someone-else wrote: the electricity is not going to complain about the colour of the insulation.
The other thing to "wonder about" is:

Is the red permanent live? it may be that the black is permanent live, unless it is tested, or traced back to the other end, no one (apart from whoever installed it) will ever know
So no risk of electrocution if the permanent live is in the switched live terminal?

Sent from my SM-G930F using Tapatalk
User avatar
someone-else
Senior Member
Posts: 8809
Joined: Sat Sep 01, 2012 6:03 pm
Has thanked: 41 times
Been thanked: 1487 times

Re: Light switch

Post by someone-else » Sun Oct 21, 2018 7:23 am

I am curious, why do you think there would be any danger / risk of death?
Fret not, a forum is a collection of opinions. Above, are mine.

Which is correct? Metre or Meter? Click the link to find out more.

Working on anything electrical? have you got a multi meter? why not? Would you hit a nail with a shoe?

If gloom had a voice, it would be me. :mrgreen:

:idea1: How to post a picture on this forum Click here
User avatar
mole81
Senior Member
Posts: 785
Joined: Mon Mar 07, 2011 2:18 pm
Has thanked: 33 times
Been thanked: 3 times

Re: Light switch

Post by mole81 » Sun Oct 21, 2018 7:28 am

someone-else wrote:I am curious, why do you think there would be any danger / risk of death?
Just because they are the wrong way round? I'm not an electrician I'm just capable of changing like for like! Suppose similar thinking if you mix up the terminals on a socket??

Sent from my SM-G930F using Tapatalk
User avatar
someone-else
Senior Member
Posts: 8809
Joined: Sat Sep 01, 2012 6:03 pm
Has thanked: 41 times
Been thanked: 1487 times

Re: Light switch

Post by someone-else » Sun Oct 21, 2018 7:46 am

Oh, I see. Thank you. :-)

I shall explain the error in your thinking.

A light switch just sits there (as wine~O said) it is either on or off.

A socket can have anything plugged into it, most devices will "not care" which way round the supply is, but some will, it is these that can be a danger, not to mention that with most sockets the integral switch only turn off the live, so if the item plugged into a reverse-wired socket was still plugged in, but switched off the device and its cable are still live (The switch only turned off the neutral) so if the device was opened (lets say to remove a blockage) it would be possible to get an electric shock as the supply is the wrong way round. That is why before you open any electrical item you must make sure it is isolated from the supply, and the easiest way to do that is to unplug it.

Where as the humble switch, you only press the button, so it matters not which terminal is the live or switched live.

But you also did the right thing, by asking. Better safe than dead.
These users thanked the author someone-else for the post:
mole81
Rating: 7.14%
Fret not, a forum is a collection of opinions. Above, are mine.

Which is correct? Metre or Meter? Click the link to find out more.

Working on anything electrical? have you got a multi meter? why not? Would you hit a nail with a shoe?

If gloom had a voice, it would be me. :mrgreen:

:idea1: How to post a picture on this forum Click here
User avatar
mole81
Senior Member
Posts: 785
Joined: Mon Mar 07, 2011 2:18 pm
Has thanked: 33 times
Been thanked: 3 times

Re: Light switch

Post by mole81 » Sun Oct 21, 2018 7:47 am

someone-else wrote:Oh, I see. Thank you. :-)

I shall explain the error in your thinking.

A light switch just sits there (as wine~O said) it is either on or off.

A socket can have anything plugged into it, most devices will "not care" which way round the supply is, but some will, it is these that can be a danger, not to mention that with most sockets the integral switch only turn off the live, so if the item plugged into a reverse-wired socket was still plugged in, but switched off the device and its cable are still live (The switch only turned off the neutral) so if the device was opened (lets say to remove a blockage) it would be possible to get an electric shock as the supply is the wrong way round. That is why before you open any electrical item you must make sure it is isolated from the supply, and the easiest way to do that is to unplug it.

Where as the humble switch, you only press the button, so it matters not which terminal is the live or switched live.

But you also did the right thing, by asking. Better safe than dead.
Ahhh thank you that makes perfect sense, thanks for the clear explanation!

Sent from my SM-G930F using Tapatalk
User avatar
someone-else
Senior Member
Posts: 8809
Joined: Sat Sep 01, 2012 6:03 pm
Has thanked: 41 times
Been thanked: 1487 times

Re: Light switch

Post by someone-else » Sun Oct 21, 2018 8:01 am

:thumbleft:
Fret not, a forum is a collection of opinions. Above, are mine.

Which is correct? Metre or Meter? Click the link to find out more.

Working on anything electrical? have you got a multi meter? why not? Would you hit a nail with a shoe?

If gloom had a voice, it would be me. :mrgreen:

:idea1: How to post a picture on this forum Click here
User avatar
ericmark
Senior Member
Posts: 2845
Joined: Tue May 10, 2011 2:43 am
Location: Mid Wales
Has thanked: 65 times
Been thanked: 565 times

Re: Light switch

Post by ericmark » Sun Oct 21, 2018 8:43 am

mole81 wrote:Just because they are the wrong way round? I'm not an electrician I'm just capable of changing like for like! Suppose similar thinking if you mix up the terminals on a socket??

Sent from my SM-G930F using Tapatalk
But they are not wrong way around, although with an on/off switch permanent line is normally com, with a two way switch permanent line is normally L1 or L2, it would be very unusual to use com as permanent line with a two way switch, and with an intermediate switch you don't have a com.

Also both wires are line, one is switched the other permanent, but both are line.

Note:- both the phase conductor and neutral are considered live, so to distinguish the phase conductor is called line and clearly neutral is called neutral, I know we often think of line and live being the same, but if I call line live some one is sure to tell me, as I should know better, no one is worried what you call it however, we all know what you mean.
User avatar
wine~o
Senior Member
Posts: 24624
Joined: Sat Jan 10, 2009 3:49 pm
Location: hants/dorset border
Has thanked: 1315 times
Been thanked: 3618 times

Re: Light switch

Post by wine~o » Sun Oct 21, 2018 4:06 pm

Well, between Someone-else and myself I thought we'd pretty much cleared up this thread in layman's terms.

and then...
Verwood Handyman

Verwood Handyman


___________________________________________________________________

If you feel you have benefited from the Free advice given on the Forum, Please consider making a donation to UHM's Nominated charity, read all about it and donate here :

http://www.donnasdreamhouse.co.uk
Bob225
Senior Member
Posts: 3474
Joined: Sun Jan 31, 2010 9:21 pm
Location: Kent, Land of Apples and PYO
Has thanked: 48 times
Been thanked: 616 times

Re: Light switch

Post by Bob225 » Sun Oct 21, 2018 4:57 pm

lol, To be pedantic the black should have a red sleeve or marker, or a bit of red insulting tape with teeth marks in it (as long as its not harmonised colours)
User avatar
mole81
Senior Member
Posts: 785
Joined: Mon Mar 07, 2011 2:18 pm
Has thanked: 33 times
Been thanked: 3 times

Re: Light switch

Post by mole81 » Sun Oct 21, 2018 6:39 pm

Thanks for all the replies, simpler wins for me!

Sent from my SM-G930F using Tapatalk
Post Reply

Return to “Lighting”