Melted plugs and sockets...

[Chappers]

Hi all,

Had two occurrences of 13A socket outlets and plugs melting after being overloaded by multi-sockets, one catching fire, the other having the live pin from the plug melted nicely into the socket. Chief Big Spark and underling - me - thought the 13A fuse in the plug should have blown before temperatures got so high, or fire broke out, if overloading the problem. Had this happen as well? Is there a simple answer?

Ta.

 

[randyrat]

Mmm...problem there alright. A 13 A fuse will not necessarily blow at 13A on the nail. There is a certain amount of short duration surge allowance, however a continuous current in excess of 13A should have blown the fuse way way way before the socket melted. More investigation required...
Was the multiplug in a double adapter? If so was this fused? If not then however many 13A plugs were running off the socket is the size of the current, i.e 2 equals 26A etc.
What I'm saying is; if there were ten plugs at 13A each.....you get the picture...the socket will be overloaded, but each individual plug will still only be drawing x amount of amps...

 

[bahco]

went to a customers last week she said he dryer had stopped working....pulled the dryer out double adaptor into the socket dryer and another appliance plugged into the adaptor.... not much left of the adaptor or the live pin on the plug.... the kitchen stunk!

i said to her did you not smell burning.... she said yeah never thought anything of it though.

haha customers dont you just love them!

 

[Chappers]

In the case of the one which had melted, no, the multi-way socket bar wasn't plugged into a double adaptor (isn't it time they were got rid of or fused - terribly dangerous things), it was plugged directly into the wall single socket.

Regarding the one where a fire started, I believe (but am not certain) that no double or triple adaptor block was used. When Chief is back off his hols, I'll have to ask him if he was involved. As far as I know, someone put out the fire with a portable extinguisher, pulled the main cut-out and the apartment's been left like that ever since. When I went in recently, most of the stuff had been removed, and only a blackened fridge remained, although I understand a portable electric cooker thing (2 hobs) was one item plugged into the extension.

 

[4x4 mark]

went to a job where the consumer unit melted and it was caused by a loose neutral from the main switch into the neutral bar, it melted the whole side of the board.
check all terminations see if any were not tight causing arking etc.

 

[WarrenG]

Probably find that there was a bit of silver paper wrapped around the fuse in the plugtop because the customer couldn't understand why the fuse kept blowing in the extension lead when they plugged in the cooker, the fridge, the microwave, the tumble dryer etc,etc............lol

 

[tim10999]

I had a similar problem the dryer stopped working, on inspecting the plug it had melted. The wiring inside the plug was wrong, blue going to live and brown going to netural. The plug was not factory installed.

Would the wiring have caused the plug to melt or just cause the motor to rotate in the other direction?
I'm in Singapore and was not sure if this was done for a reason or just shoddy wiring.

Thanks

 

[malcolmsanford]

As your in Singapore the unit may have only been a 2 wire design and if that is the case then it is not relevant which cable goes where.

In the Europe a lot of the modern machines utilize electronics and in some cases these need to be polarity conscious ie having the LINE/NEUTRAL connected correctly, but if that was the case here the machine would not work from the beginning.

Generally speaking if you have a basic unit it would not really matter which way the unit was connected until you got a fault on it, and that could cause you real problems.

The chances are the cable and plug burnt out due to a faulty connection rather than reversed polarity. To be honest until recently in Far East countries, and even today in many, cable colours and polarity was never a priority for local electricians, so what you would identify as "should be" LINE/NEUTRAL because of the colours often bear no resemblance

 

[tim10999]

Thanks for the quick response. Looking back at the previous threads it could be that the plug was poorly rewired and shorted in the plug causing it to melt.

It's a new condo and there seem to be a few problems with the wiring such as you cannot turn the fan on without turning on a light.

Thanks

As your in Singapore the unit may have only been a 2 wire design and if that is the case then it is not relevant which cable goes where.

In the Europe a lot of the modern machines utilize electronics and in some cases these need to be polarity conscious ie having the LINE/NEUTRAL connected correctly, but if that was the case here the machine would not work from the beginning.

Generally speaking if you have a basic unit it would not really matter which way the unit was connected until you got a fault on it, and that could cause you real problems.

The chances are the cable and plug burnt out due to a faulty connection rather than reversed polarity. To be honest until recently in Far East countries, and even today in many, cable colours and polarity was never a priority for local electricians, so what you would identify as "should be" LINE/NEUTRAL because of the colours often bear no resemblance

 

[Guest111]

75% of all electrical related house fires are caused by double adapters,worst things ever imo not only are most of them unfused but they also place excessive strain on the contact tubes in the socket.

 

[Richard Burns]

Melting plugs is generally due to loose connections, dirt/corrosion on contacts, poor plug/socket design leading to partial connection.
This effectively gives a small are of contact equivalent to a low cross sectional area with correspondingly low current carrying capacity.
Where there is resistance to the current flow from such a cause then the conductor will heat up and more corrosion will occur exacerbating the problem.
If enough current is pulled for long enough then the plastic starts to melt even though the current may be below 13A.

 

[Inteificio]

"A 13 A fuse will not necessarily blow at 13A on the nail"

Can't remember precisely off the top of my head, but it is not supposed to blow, even on long load, from between 20-26A. The sockets are rated to take this in to account.
Google BS1362 disconnection chart for precise figures.

My money is on poor connections and arcing. That would keep the fuse in place but generate extra heat.


​

 

[Taylortwocities]

Cartridge fuses can carry slight overload currents for hours, and may never "blow"

There's a good explaination here http://www.tlc-direct.co.uk/Book/3.6.2.htm and the graphs in the following section are worth a look (for those without the BRB).
Note the extract relates to 16th edition but the principles haven't changed.

 

[Engineer54]

As your in Singapore the unit may have only been a 2 wire design and if that is the case then it is not relevant which cable goes where.

Singapore basically follows the British Reg's, and uses standard UK wall accessories and plug tops.. Well it did up until 10 years ago, which was the last time i was in Singapore... lol!!

 

[malcolmsanford]

Last time I was there, admittedly a little longer than 10yrs back Col there was a load of American Westinghouse equipment that used the old 2 wire system.