Sockets: reverse L and N - consequences?

[STD Warehouse]

Trying to understand.

 

A so called “electrician” (who knows what real training he had) came in and changed some of my sockets to Panosonic brand as the old universal ones where totally jammed and wouldn’t allow any plug to be plugs in.

 

I tested them yesterday and my tester plug said the live and neutral had been put the wrong way in. As well as some of the earths not even being connected to the sockets.

 

So I’ve decided to changed the remaining universal sockets to Panosonic branded ones. 

 

Why’s it like this?

 

Two browns going into first socket are Live, two blues are neutral.

 

Then one live brown and one blue neutral goes to second socket.

 

My socket tester shows the live and neutral have been incorrectly installed into the second socket, theve been switched. As shown in photo, live brown is going into neutral side of socket and blue neutral is going into live side of socket.

 

But socket still works, if I didn’t have a tester I would not have known apart from when opening it up to look.

 

Coming out of that socket the brown is now neutral and the blue is now live… these just go up to a light above and nowhere else, and that light is not in use. So no harm done.

 

But my question is:

 

What would happen if these two reversed cables went somewhere? Like if the blue was going back to the consumer unit but was now actually a live cable and not a neutral cable?

[DudleySquat]

Was he barefoot the entire time? 

 

That's all you need to know.

[worgeordie]

The L and N are reversed here than say the UK , other countries I don't know .

and the problem here the colour of wires does not seem to be standardized ,

seen a multitude of colours used here.....but in your case brown should be L

and blue N 

 

regards worgeordie 

[STD Warehouse]

2 minutes ago, worgeordie said:

The L and N are reversed here than say the UK , other countries I don't know .

and the problem here the colour of wires does not seem to be standardized ,

seen a multitude of colours used here.....but in your case brown should be L

and blue N 

 

regards worgeordie 

Yes thank you

 

but what happens if you reverse them and so sending a live wire back to the consumer unit, which was previously a neutral wire?

[HauptmannUK]

You can't really 'send a live back to the consumer unit'.  Whatever wire is connected to the Neutral busbar is Neutral and whichever wires are connected to Live breakers will be live. What colour they are and where they go to at the outlet is another matter.

In Thailand the outlet N is supposed to be clockwise from the Earth pin (looking into a wall mounted socket). This is US-style and OPPOSITE to UK-style, where its L that is clockwise from E. 

Anyway, Thai electricians often play fast-and-loose with L and N.

Obviously there is a danger in swapping them over because most appliances will have a single pole switch on the incoming Live.  If L and N are swapped over then the appliance internals will still be live even when the appliance is switched off because you are switching the N and not L!

Ideally have all your blue conductors connected to N busbar in the consumer unit and connected to the pin clockwise from E at your outlets. All brown conductors running from breakers to the pins anticlockwise from E at the outlets.

[STD Warehouse]

16 minutes ago, HauptmannUK said:

You can't really 'send a live back to the consumer unit'.  Whatever wire is connected to the Neutral busbar is Neutral and whichever wires are connected to Live breakers will be live. What colour they are and where they go to at the outlet is another matter.

In Thailand the outlet N is supposed to be clockwise from the Earth pin (looking into a wall mounted socket). This is US-style and OPPOSITE to UK-style, where its L that is clockwise from E. 

Anyway, Thai electricians often play fast-and-loose with L and N.

Obviously there is a danger in swapping them over because most appliances will have a single pole switch on the incoming Live.  If L and N are swapped over then the appliance internals will still be live even when the appliance is switched off because you are switching the N and not L!

Ideally have all your blue conductors connected to N busbar in the consumer unit and connected to the pin clockwise from E at your outlets. All brown conductors running from breakers to the pins anticlockwise from E at the outlets.

Thank you! Some useful explanations and advice.

[OneMoreFarang]

In most cases it won't make a difference if L and N are reversed.

My reasoning for that are plugs in other countries, like Schuko plugs in Europe, are symmetrical, there is no L or N.

From my time over there I don't remember any device with information like "the plug must connected like this or that".

The same devices are used all over the world with just different plugs. Same, same, not much different.

 

https://en.wikipedia.org/wiki/Schuko

"Schuko plugs and sockets are symmetric AC connectors. They can be mated in two ways, therefore line can be connected to either pin of the appliance plug."

 

This is not a professional electrician's answer. If you know better, then please correct me. 

[Crossy]

As above, with modern appliances it doesn't usually matter, many have 2-pin plugs that are reversible anyway.

 

BUT

 

If your appliance has a single-pole switch or an internal fuse it should be in the live line, otherwise with the switch open or the fuse popped all the internal gubbins is still live. Of course, you shouldn't be poking around in there with the plug in anyway.

 

It's just best to be correct.

 

[Muhendis]

With some equipment like an oven for example, there can be a problem with live and neutral reversed. The element switches are all on the live side so a reversed L-N would mean switching on the neutral side. 

[sometimewoodworker]

2 hours ago, HauptmannUK said:

You can't really 'send a live back to the consumer unit'.

If you are wiring as a ring circuit (a circuit that though common in the U.K. should never be used) then yes you can 

2 hours ago, HauptmannUK said:

In Thailand the outlet N is supposed to be clockwise from the Earth pin (looking into a wall mounted socket). This is US-style and OPPOSITE to UK-style, where it’s L that is clockwise from E. 

that depends on the hardware you buy. I have Thai hardware where the coding is the same as the US style, and yes yet is Thai hardware as the 3 pins are round. Also if you orient the socket in the correct way when vertical with the earth pin at the top then they are US style. The correct orientation is line at 9 earth at 12 and neutral at 3

2 hours ago, HauptmannUK said:

Obviously there is a danger in swapping them over because most appliances will have a single pole switch on the incoming Live.  If L and N are swapped over then the appliance internals will still be live even when the appliance is switched off because you are switching the N and not L!

Obviously there is no danger as the Thai flat 2 pin plugs are gender neutral 

 

They very rarely have switches and only a fool would use a single pole switch where the L and  N are easily reversed.

[sometimewoodworker]

Just now, Muhendis said:

With some equipment like an oven for example, there can be a problem with live and neutral reversed. The element switches are all on the live side so a reversed L-N would mean switching on the neutral side. 

Where the is an appliance where the line neutral need to be oriented then you should never use a 2 pin socket, only ever direct wired or 3 pin socket where the line is correct wired for the orientation of your appliances.

 

 

[herfiehandbag]

7 minutes ago, sometimewoodworker said:

Obviously there is no danger as the Thai flat 2 pin plugs are gender neutral 

So what pronouns do they use?

[Crossy]

The observant among us will notice that, like the US, Thai outlets are actually polarised even for 2-pin plugs (the neutral pin is wider).

 

Of course, the vast majority of Thai plugs have pins of equal width so they will go either way round as will the round-pin Euro plug.

 

The Haco P-001 (sadly now defunct) was an example of a polarised 2-pin plug.

[Muhendis]

3 hours ago, Crossy said:

The observant among us will notice that, like the US, Thai outlets are actually polarised even for 2-pin plugs (the neutral pin is wider).

 

Of course, the vast majority of Thai plugs have pins of equal width so they will go either way round as will the round-pin Euro plug.

 

The Haco P-001 (sadly now defunct) was an example of a polarised 2-pin plug.

Well said and

Happy New Year

[Muhendis]

3 hours ago, herfiehandbag said:

So what pronouns do they use?

It.....

Have I won a prize?

[HauptmannUK]

6 hours ago, sometimewoodworker said:

If you are wiring as a ring circuit (a circuit that though common in the U.K. should never be used) then yes you can 

that depends on the hardware you buy. I have Thai hardware where the coding is the same as the US style, and yes yet is Thai hardware as the 3 pins are round. Also if you orient the socket in the correct way when vertical with the earth pin at the top then they are US style. The correct orientation is line at 9 earth at 12 and neutral at 3

Obviously there is no danger as the Thai flat 2 pin plugs are gender neutral 

 

They very rarely have switches and only a fool would use a single pole switch where the L and  N are easily reversed.

What motivated you to write that nonsense in response to my post?

Firstly, with a ring main you are not 'sending a live back to the consumer unit'.

Secondly, you say L and N orientation 'depends on the hardware you buy'. No it doesn't. N should always be clockwise from the E pin (as per the photo you included) irrespective of receptacle type or orientation or markings.

Thirdly, there IS an obvious danger if L and N are transposed. There ARE appliances sold where there is a single pole switch on the L side.  The fact that there are plugs available with two equal width flat pins is irrelevant. The flat receptacles on Thai sockets are actually polarised by width - N is wider. But when supplying an appliance with a type O plug the manufacturer will switch on the L side. Moreover some appliances have an internal fuse on the incoming L.

And of course in lighting units you should preserve correct L and N orientation because the screw shell in ES fittings should always be Neutral - swapping L/N will make the screw shell always live, presenting a shock hazard when a bulb is changed.

[brianthainess]

The Blue wire, an industrial electrician once told me, that blue is always the cold wire, i.e. not hot/live.

          my memory could be wrong but normally it aint  

[brianthainess]

we have a 2 pin electric barbeque  that takes water, (my rcd had been switched off) I touched it and got a shock, a Thai guy there simply pulled the plug out and reversed it problem solved.

[Bday Prang]

20 minutes ago, brianthainess said:

The Blue wire, an industrial electrician once told me, that blue is always the cold wire, i.e. not hot/live.

          my memory could be wrong but normally it aint  

Regardless of your memory being right or wrong he'd get a "shock" if he ever comes to work here

[Bday Prang]

18 minutes ago, brianthainess said:

we have a 2 pin electric barbeque  that takes water, (my rcd had been switched off) I touched it and got a shock, a Thai guy there simply pulled the plug out and reversed it problem solved.

Thats scary  I'd bin it,  or at least earth it!   on my consumer unit there is a switch which says off /  on  for the elcb  but when it was switched "on" it didn't trip when i pressed the test button,  I asked crossy about it , turned out that the switch related to  a bypass for the elcb  ( not sure what purpose that served ) and should be set to "off"   good job I asked,  Nothing on the box indicated this!

[bluejets]

7 hours ago, brianthainess said:

a Thai guy there simply pulled the plug out and reversed it problem solved.

I seriously doubt that......sounds very much like an across the counter quote on pub night.

[Crossy]

39 minutes ago, bluejets said:

I seriously doubt that......sounds very much like an across the counter quote on pub night.

 

I've actually seen it a few times. If the leak is towards one end of the element, then swapping the plug moves the leaky bit nearer N. Not recommended of course, but ...

 

Also, once it's been on for a while the leak (damp in the sand-filled element) can go away.

 

Literally last week a mate called me, both his ovens tripped his RCD. "Have they been in storage for a while?". "Yes, 3 years". He has a split CU with some unprotected outlet circuits, running the ovens on the unprotected side for 30 minutes dried out the elements and all was good when back on the protected side. Happy bunny (happy wife), beer for me

 

Similar "fixes" for people running desktop PCs on 2-pin leads, depends upon the actual configuration of the mains inlet filter in the PSU.

[sometimewoodworker]

10 hours ago, HauptmannUK said:

What motivated you to write that nonsense in response to my post?

That you are making incorrect statements.

10 hours ago, HauptmannUK said:

Firstly, with a ring main you are not 'sending a live back to the consumer unit'.

Not a way that an electrician would phrase it since the circuit of course is feeding from both sides however for a non electrician specially one who doesn’t actually know electrical theory a way to describe it.

But of course you wouldn’t understand that.

10 hours ago, HauptmannUK said:

Secondly, you say L and N orientation 'depends on the hardware you buy'. No it doesn't. N should always be clockwise from the E pin (as per the photo you included) irrespective of receptacle type or orientation or markings.

Well yes it does rather matter on the hardware you buy. I showed a socket that has polarity on the flat pins. I have, and have seen, many that are unpolarised and have no markings to indicate wire orientation, so while your electriction’s mind may be deeply offended few care or pay any attention to what should be be

 

10 hours ago, HauptmannUK said:

The fact that there are plugs available with two equal width flat pins is irrelevant.

That the vast majority of flat pin plugs that I have seen, and have, is completely relevant.

If you have always used unpolarised plugs you will naturally assume that this is the “standard” and as such you will have a 50/50 chance of wiring sockets “the right way”

All you have to do is read a few of the many reports here to know the truth of that

The majority of “electricians” working in domestic wiring have no technical training or certification.

 

You have to work in the real world, not the idealistic one where things are always correct.

10 hours ago, HauptmannUK said:

of course in lighting units you should preserve correct L and N orientation because the screw shell in ES fittings should always be Neutral - swapping L/N will make the screw shell always live, presenting a shock hazard when a bulb is changed.

Of course you should but the truth is that it’s a 50/50 chance that it’s been done correctly and a very good chance that it will never matter.

[recom273]

18 hours ago, Crossy said:

The observant among us will notice that, like the US, Thai outlets are actually polarised even for 2-pin plugs (the neutral pin is wider).

 

Of course, the vast majority of Thai plugs have pins of equal width so they will go either way round as will the round-pin Euro plug.

 

The Haco P-001 (sadly now defunct) was an example of a polarised 2-pin plug.

 

Is there any replacement for the Haco plug? Something of similar quality?

 

I have a stock of spares but its running low.

[Crossy]

4 minutes ago, recom273 said:

Is there any replacement for the Haco plug? Something of similar quality?

I have a stock of spares but its running low.

 

Not that I've found yet

 

These ones by Vena are pretty good but they don't do the vertical "hang the cable down the wall" variety

 

[sometimewoodworker]

1 hour ago, Crossy said:

 

Not that I've found yet

 

These ones by Vena are pretty good but they don't do the vertical "hang the cable down the wall" variety

 

Regrettably they also have a two pin version so you can guarantee that however it’s wired there is an even chance of either pin being connected to line