frizzled Line socket - why is it always L?

[SparkyTris]

Saw one of these tother day (see photo)
I've seen a few like this over the years, and it seems to be always the L conductor that cooks up. whenever Ive seen this, it's been in "known dodgy" situations (ie, where unregulated DIY shenanigans are continuously ongoing, with operators who are comfortable with a bit of risk)

Ive wondered, whenever Ive seen these, (and not having seen the exact installation that led up to the cookery) what causes it.

clearly it's caused by overheating around the L pin/socket interface. That could come from EITHER:
> >13A flowing in the L line but NOT in the N line, in which case, the current must be flowing to earth outwith the plug/socket circuit.
a resistive connection in (or near to) the L pin/socket interface.

I cant think of any other cause.

I guess my beef is that my first thought is forced overloading of the plug/socket, but that should result in both L & N cooking up. but I don't think Ive ever seen N cooked.

whats the explanation of why (in my experience) its only every the L pin thats fried?

 

[Risteard]

Saw one of these tother day (see photo)
I've seen a few like this over the years, and it seems to be always the L conductor that cooks up. whenever Ive seen this, it's been in "known dodgy" situations (ie, where unregulated DIY shenanigans are continuously ongoing, with operators who are comfortable with a bit of risk)

Ive wondered, whenever Ive seen these, (and not having seen the exact installation that led up to the cookery) what causes it.

clearly it's caused by overheating around the L pin/socket interface. That could come from EITHER:
> >13A flowing in the L line but NOT in the N line, in which case, the current must be flowing to earth outwith the plug/socket circuit.
a resistive connection in (or near to) the L pin/socket interface.

I cant think of any other cause.

I guess my beef is that my first thought is forced overloading of the plug/socket, but that should result in both L & N cooking up. but I don't think Ive ever seen N cooked.

whats the explanation of why (in my experience) its only every the L pin thats fried?

It's not always the line, but a logical explanation would of course be a loose connection between the fuse and carrier.

 

[JohnW2]

It's not always the line, ...

Maybe not, but I don't recall having seen one which wasn't - but, as you imply, aloose connection to the neutral pin could theoretically result in thermal damage in the vicinity of that pin.

.... but a logical explanation would of course be a loose connection between the fuse and carrier.

Yes, I think that is the generally-held assumption.

 

[RandomGrinch]

With a couple of examples picked randomly from the forum...

The damage may not always be on the line side.

However, a loose connection between fuse and carrier, will still likely be to blame...

 

[JohnW2]

With a couple of examples picked randomly from the forum... The damage may not always be on the line side.

Sure, as I said, it's far from impossible that the connection to the neutral pin could be lose, leading to overheating and thermal damage, but we only fairly rarely seem to see or hear about that.

However, a loose connection between fuse and carrier, will still likely be to blame...

Again as said, that would seem to be the most likely explanation in many/most cases.

 

[RandomGrinch]

Again as said, that would seem to be the most likely explanation in many/most cases.

That was the implication from the random pictures - nearly all the images I've seen, where the socket damage appears to be around the neutral side, could be explained by poor contact resistance from a sideways mounted fuse in a moulded plug.

 

[Jurassicspark]

Also a lot of these double pole switches fail and cause a mini arc where the switch is. It has the potential to burn your finger. MK has recently recalled one of their sockets due to this issue.

Big Clive recently done a flame test on one.

 

[pete01]

Bizarrely 13 amp socket outlets don't like 13 amps for long

 

[JohnW2]

That was the implication from the random pictures - nearly all the images I've seen, where the socket damage appears to be around the neutral side, could be explained by poor contact resistance from a sideways mounted fuse in a moulded plug.

Did you mean to write "nearly all .... around the neutral side" (which is contrary to my experience)?

 

[JohnW2]

Bizarrely 13 amp socket outlets don't like 13 amps for long

Indeed - as often discussed here. Even more so with 2 x 13A with a doublesocket.

 

[pete01]

Indeed - as often discussed here. Even more so with 2 x 13A with a doublesocket.

Yes but if it says 13 amps then that's what it should do dont you think?

I did fit a twin for my washing machine and dishwasher and I've had no problem in 5 years, I do however think about it as I switch them on together

 

[EFLImpudence]

Indeed - as often discussed here. Even more so with 2 x 13A with a doublesocket.

As I have said before, I have known one plug used with a plug-in timer that has been supplying an immersion 'for ever'.

Some must simply wear out too quickly.

 

[plugwash]

Also a lot of these double pole switches fail and cause a mini arc where the switch is. It has the potential to burn your finger. MK has recently recalled one of their sockets due to this issue.

To be specific, MK recalled the "essentials"* double switched sockets, both single pole and double pole variants and versions with and without neons and USB. They did not recall the unswitched sockets, nor did they recall the single switched sockets.

And it seems the recall was only a "removal from the market" rather than a full-on consumer recall.

Clive did a video on one of the socket, and there is some interesting discussion in the comments, suggesting that the problem might have been that not only did the switch arc, but the arc then caused a flashover to neutral or earth.

 

[JohnW2]

As I have said before, I have known one plug used with a plug-in timer that has been supplying an immersion 'for ever'.
Some must simply wear out too quickly.

Yes, I agree - but that "wearing out too quickly" could well be a reflection of less-than-deal contact between fuse and holder in a particular plug, couldn't it?

 

[big-all]

could it be you have 3 points one after the other to cause possible resistance and whilst any one on its own will be absorbed by the pin and connected wire just fine
now iff they are all warming up a bit there is nothing to absorb the excess heat