Wiring new ceiling light LED

grumbler

binft said:

grumbler said:

binft said:

Cornucopia said:

Those cables are ancient - the color scheme before the last one.   Google says pre-1977.  You might want to get a professional opinion on whether re-wiring would be recommended.

As always, mains voltages are dangerous, and it's bad idea to work with wiring unless you know what you are doing.

It will (probably) be the two black wires you need, unless your new fitting has metal parts and requires an Earth connection (that will be the green).

I assume where you say "normal 12v" that's a typo.   This is of course 240v mains wiring.   If your LED unit needs 12v, then you need a transformer, too.

  New led lamp is straight positive/negative connection no other cables so that's why I thought it would be a straight swap as they are indicated to be this kind of swap when you read the description on them.

Positive/negative indicates 12V - if this really is the case. Hard to believe. Can you post a photo or a link?

see below
and this is the old light connection that had the two black cables in it 

Both are 240V Live and Neutral, not positive and negative. Live is AC (alternating voltage)

ETA: I don't think that this is really important, but it's still worth finding out which one of two black wires is switched live and connect it to the brown (L) wire of the lamp. Most likely, it doesn't matter which wire is connected to which.

Section62

binft said:

Yeah my plan was to check which is pos and neg with the multimeter, then turn off electrics, wire up and turn back on to see, just never seen them as double black before usually red/black but that's probably not the norm for house wiring.

Be really careful about assuming any meaning of wiring colours - especially in a 1970's system where it is sometimes possible the lightswitch has been inserted into the neutral side.  In fact neutral switching is still a risk with any wiring which hasn't been done professionally, but with older wiring even the professionals worked with different standards to those used today.

The only thing it is safe to assume is that any wire (including the green ones) could be at a dangerous voltage, unless proven otherwise.

binft

grumbler said:

binft said:

grumbler said:

binft said:

Cornucopia said:

Those cables are ancient - the color scheme before the last one.   Google says pre-1977.  You might want to get a professional opinion on whether re-wiring would be recommended.

As always, mains voltages are dangerous, and it's bad idea to work with wiring unless you know what you are doing.

It will (probably) be the two black wires you need, unless your new fitting has metal parts and requires an Earth connection (that will be the green).

I assume where you say "normal 12v" that's a typo.   This is of course 240v mains wiring.   If your LED unit needs 12v, then you need a transformer, too.

  New led lamp is straight positive/negative connection no other cables so that's why I thought it would be a straight swap as they are indicated to be this kind of swap when you read the description on them.

Positive/negative indicates 12V - if this really is the case. Hard to believe. Can you post a photo or a link?

see below
and this is the old light connection that had the two black cables in it 

Both are 240V Live and Neutral, not positive and negative. Live is AC (alternating voltage)

ETA: I don't think that this is really important, but it's still worth finding out which one of two black wires is switched live and connect it to the brown (L) wire of the lamp. Most likely, it doesn't matter which wire is connected to which.

Are you saying only 1 of the black wires need to be connected to the Brown L of the new lamp, not both?

*edit*

actually I see what you mean, just watched some videos explaining basic ceiling light electricals and went over switched lives etc.

grumbler

binft said:

grumbler said:

binft said:

grumbler said:

binft said:

Cornucopia said:

Those cables are ancient - the color scheme before the last one.   Google says pre-1977.  You might want to get a professional opinion on whether re-wiring would be recommended.

As always, mains voltages are dangerous, and it's bad idea to work with wiring unless you know what you are doing.

It will (probably) be the two black wires you need, unless your new fitting has metal parts and requires an Earth connection (that will be the green).

I assume where you say "normal 12v" that's a typo.   This is of course 240v mains wiring.   If your LED unit needs 12v, then you need a transformer, too.

  New led lamp is straight positive/negative connection no other cables so that's why I thought it would be a straight swap as they are indicated to be this kind of swap when you read the description on them.

Positive/negative indicates 12V - if this really is the case. Hard to believe. Can you post a photo or a link?

see below
and this is the old light connection that had the two black cables in it 

Both are 240V Live and Neutral, not positive and negative. Live is AC (alternating voltage)

ETA: I don't think that this is really important, but it's still worth finding out which one of two black wires is switched live and connect it to the brown (L) wire of the lamp. Most likely, it doesn't matter which wire is connected to which.

Are you saying only 1 of the black wires need to be connected to the Brown L of the new lamp, not both?

I don't know. It was you who disconnected the old lamp and said "only the two black wires were connected to the old light and i've found two more red ones tucked up out the way, "

If the old light was connected to two black wires (and the red wire wasn't used), then so has to be the new light.

ETA: and if two black wires were connected to L and N terminals of the old light, then you'll short-circuit them if you connect both to the L terminal of the new lamp. And what were you going to connect to N in this case?

daveyjp

Never disconnect a light fitting or switch until you have taken note (and photos) of which wires went into which terminal!

Also from my recent experience of changing a kitchen light to an LED strip light those quick connectors are hopeless.  I cut it off and used a proper connecting block.

Risteard

grumbler said:

binft said:

grumbler said:

binft said:

Cornucopia said:

Those cables are ancient - the color scheme before the last one.   Google says pre-1977.  You might want to get a professional opinion on whether re-wiring would be recommended.

As always, mains voltages are dangerous, and it's bad idea to work with wiring unless you know what you are doing.

It will (probably) be the two black wires you need, unless your new fitting has metal parts and requires an Earth connection (that will be the green).

I assume where you say "normal 12v" that's a typo.   This is of course 240v mains wiring.   If your LED unit needs 12v, then you need a transformer, too.

  New led lamp is straight positive/negative connection no other cables so that's why I thought it would be a straight swap as they are indicated to be this kind of swap when you read the description on them.

Positive/negative indicates 12V - if this really is the case. Hard to believe. Can you post a photo or a link?

see below
and this is the old light connection that had the two black cables in it 

Both are 240V Live and Neutral, not positive and negative. Live is AC (alternating voltage)

ETA: I don't think that this is really important, but it's still worth finding out which one of two black wires is switched live and connect it to the brown (L) wire of the lamp. Most likely, it doesn't matter which wire is connected to which.

Actually, to be accurate, it's line (phase) and neutral. Both of these are live conductors. Neutral is every bit as much a live conductor as a phase conductor is.

grumbler

Risteard said:

grumbler said:

binft said:

grumbler said:

binft said:

Cornucopia said:

Those cables are ancient - the color scheme before the last one.   Google says pre-1977.  You might want to get a professional opinion on whether re-wiring would be recommended.

As always, mains voltages are dangerous, and it's bad idea to work with wiring unless you know what you are doing.

It will (probably) be the two black wires you need, unless your new fitting has metal parts and requires an Earth connection (that will be the green).

I assume where you say "normal 12v" that's a typo.   This is of course 240v mains wiring.   If your LED unit needs 12v, then you need a transformer, too.

  New led lamp is straight positive/negative connection no other cables so that's why I thought it would be a straight swap as they are indicated to be this kind of swap when you read the description on them.

Positive/negative indicates 12V - if this really is the case. Hard to believe. Can you post a photo or a link?

see below
and this is the old light connection that had the two black cables in it 

Both are 240V Live and Neutral, not positive and negative. Live is AC (alternating voltage)

ETA: I don't think that this is really important, but it's still worth finding out which one of two black wires is switched live and connect it to the brown (L) wire of the lamp. Most likely, it doesn't matter which wire is connected to which.

Neutral is every bit as much a live conductor as a phase conductor is.

Well, did you ever measure the voltage between Neutral and Earth? It's close to zero (if there are no faults). Between Line and Earth it's 240.

grumbler

daveyjp said:

Also from my recent experience of changing a kitchen light to an LED strip light those quick connectors are hopeless.  I cut it off and used a proper connecting block.

If you mean the connector in the new light, it seems to be a 'proper connecting block' with screws.

That said, modern 'maintenance free' connectors are 'quick' (no screws) and are deemed more reliable (for solid wires only?) than traditional.

Ectophile

grumbler said:

Risteard said:

grumbler said:

binft said:

grumbler said:

binft said:

Cornucopia said:

Those cables are ancient - the color scheme before the last one.   Google says pre-1977.  You might want to get a professional opinion on whether re-wiring would be recommended.

As always, mains voltages are dangerous, and it's bad idea to work with wiring unless you know what you are doing.

It will (probably) be the two black wires you need, unless your new fitting has metal parts and requires an Earth connection (that will be the green).

I assume where you say "normal 12v" that's a typo.   This is of course 240v mains wiring.   If your LED unit needs 12v, then you need a transformer, too.

  New led lamp is straight positive/negative connection no other cables so that's why I thought it would be a straight swap as they are indicated to be this kind of swap when you read the description on them.

Positive/negative indicates 12V - if this really is the case. Hard to believe. Can you post a photo or a link?

see below
and this is the old light connection that had the two black cables in it 

Both are 240V Live and Neutral, not positive and negative. Live is AC (alternating voltage)

ETA: I don't think that this is really important, but it's still worth finding out which one of two black wires is switched live and connect it to the brown (L) wire of the lamp. Most likely, it doesn't matter which wire is connected to which.

Neutral is every bit as much a live conductor as a phase conductor is.

Well, did you ever measure the voltage between Neutral and Earth? It's close to zero (if there are no faults). Between Line and Earth it's 240.

It's just the people writing the standards using terminology that doesn't match what ordinary people think words mean.

Both the "Live" and "Neutral" have been declared to be live conductors. Which means that the "Live" has to be called "Line" or "Phase", because the Neutral is now live.

Section62

Ectophile said:

It's just the people writing the standards using terminology that doesn't match what ordinary people think words mean.

Both the "Live" and "Neutral" have been declared to be live conductors. Which means that the "Live" has to be called "Line" or "Phase", because the Neutral is now live.

It isn't really about the standards writers, it is just another unfortunate case where a word which actually has an established technical meaning doesn't mean what people think it means when they commonly use it.  Just like people say "footpath" or "pavement" when they mean "footway", or "investments" when they mean "savings".

Sometimes it matters to use the correct terminology in conversation - for example clarifying whether that "footpath" is really a path running through a field or not - but sometimes it is better to avoid using terms which would only confuse someone who isn't likely to understand what you mean without a lot more explanation (e.g. "phase")

Accuracy gets more important when you talk about something like electricity which has the capability to kill if a misunderstanding leads to something being done which shouldn't be done. But it is also important to make sure the person you are communicating with is understanding the words you are using, rather than assuming they will because they are the technically correct ones.

Electrically, 'live' means a conductor through which a current is flowing.

It technical vs common use issue works the other way too.  People commonly use "live wire" to refer to a person who is energised or active, inadvertently (perhaps) using 'live' in its correct meaning. Assuming that is what they mean, and they aren't talking about someone coated in brown PVC and intended to conduct electricity at a potential of 230v RMS referenced to ground.