Blown Wall Plug - Advice Needed!

[melmerby]

1 hour ago, 96701 said:

Woah, woah, woah. It cost us a huge amount of money to replace our consumer unit and on top of that got all sorts of spurious trippings of the new RCDs, so yes, they do offer much greater protection, the cost being high to replace the consumer unit and various items from outside lighting to tape recorder / player from the hi-fi stack.

 

If you needed to replace so much stuff it was probably in need of replacing anyway.

And yes I have outside lights, 4 various types regularly soaked by rain and no problems

Equipment in good order does not trip RCDs.

I've been using them for donkey's years and never had a problem

.

Edited February 9, 2019 by melmerby

[Dave John]

Hmm, define a huge amount of money 96701? 

 

The way I look at is this ; What is your house and contents including all those hand built model railway items worth ? What is your families safety worth ? If you live in a block of flats as I do what is the safety of your friends and neighbours worth ? 

 

All of a sudden it might not seem such a huge amount. If you had a dangerous gas appliance would you baulk at the cost of getting it fixed ? 

 

I have been involved with fire investigations and have seen the devastation it all causes. Upgrading the electrical installation is always money well spent. 

 

 

[96701]

44 minutes ago, Dave John said:

Hmm, define a huge amount of money 96701? 

 

The way I look at is this ; What is your house and contents including all those hand built model railway items worth ? What is your families safety worth ? If you live in a block of flats as I do what is the safety of your friends and neighbours worth ? 

 

All of a sudden it might not seem such a huge amount. If you had a dangerous gas appliance would you baulk at the cost of getting it fixed ? 

 

I have been involved with fire investigations and have seen the devastation it all causes. Upgrading the electrical installation is always money well spent. 

 

 

Okay, point taken.

[kevinlms]

3 hours ago, Dave John said:

Hmm, define a huge amount of money 96701? 

 

The way I look at is this ; What is your house and contents including all those hand built model railway items worth ? What is your families safety worth ? If you live in a block of flats as I do what is the safety of your friends and neighbours worth ? 

 

All of a sudden it might not seem such a huge amount. If you had a dangerous gas appliance would you baulk at the cost of getting it fixed ? 

 

I have been involved with fire investigations and have seen the devastation it all causes. Upgrading the electrical installation is always money well spent. 

 

 

A classic example of the wrong attitude, is the Glenfell fire.

 

At least this similar fire  in Melbourne (it has identical cladding), had a decent sprinkler system and a partly working fire alarm.

 

https://www.theage.com.au/national/victoria/smoke-alarm-system-dilapidated-before-fire-ripped-through-cbd-tower-20190208-p50wkv.html

[Bristol_Rich]

Just out of curiosity if you’ve been smelling an intensely strong smell of ‘fish’ this usually the smell of the plastic getting hot in the wall socket/ plug...

[Ray Von]

Here is the offending socket, it is situated behind a floor length curtain - so could've been a lot worse!!

 

The tape is temporary.

[melmerby]

That I would suggest is the socket itself getting hot.

Whether it was the original cause or the plug might be hard to determine now.

 

E.g. poor contact on live terminal in plug (maybe the fuse holder, increasing resistance), plug pin gets very hot, - heat travels to contacts in socket, weakens the contact tension, increases resistance causing the the contact itself to get hot (or vice versa)

Either way both need replacing. 

Edited February 10, 2019 by melmerby

[Ray Von]

Cheers, the plug itself is long gone - should've taken a pic really.

 

Replaced it earlier today, and the dryer is currently tumbling away quite nicely - I am using a different socket though!

 

This has been a real eye-opener for me, I have to say.  I've always laboured under the impression that you could rely on the fuse in a plug to save the day in the event of an overload (or whatever this was...) Clearly this is not always the case!

 

Thanks to all that have responded so far.

[melmerby]

3 hours ago, Ray Von said:

 I've always laboured under the impression that you could rely on the fuse in a plug to save the day in the event of an overload (or whatever this was...) Clearly this is not always the case!
 

A poor connection isn't an overload and there is no way a fuse or MCB can give protection.

At no time would the current exceed the rating until some destruction has already taken place.

Then carbonised plastic (or other material) makes a low resistance path and something gives (hopefully before a fire has started)

[AndyID]

Ray,

 

 Even though you are running the dryer on another socket please have that bad socket replaced ASAP.

 

It's quite possible that the oxidation has effectively "broken" the ring main continuity and that can lead to other problems. It's also possible for the bad socket to dissipate heat even though there is nothing plugged into it.

 

Andy

[Suzie]

I rather feel that with the socket in that state the circuit needs to be isolated until the socket is replaced. Sticky tape is not good enough to ensure safety.

 

Cause of the failure is going to be hard to determine, but in the mean time you might like to run the tumble dryer through a plug-in RCD if you do not have one fitted since you cannot rule out a possible fault in the tumble dryer that may still be present. Fit a good quality (MK or similar) plug to minimise that possibility of the plug failing. A loose fuse is likely to result in a similar situation.

 

This is the sort of thing that happens when sockets are worn due to too much plugging in and out, and the unnecessary use of 'Socket protectors'.

[kevinlms]

9 hours ago, Ray Von said:

Cheers, the plug itself is long gone - should've taken a pic really.

 

Replaced it earlier today, and the dryer is currently tumbling away quite nicely - I am using a different socket though!

 

This has been a real eye-opener for me, I have to say.  I've always laboured under the impression that you could rely on the fuse in a plug to save the day in the event of an overload (or whatever this was...) Clearly this is not always the case!

 

Thanks to all that have responded so far.

You do realise that most of the world does NOT have fuses in the plugs. Britain is a rarity.

As you have discovered, it is not a fool proof solution. It only protects a fault within the device and not the wall plate.

[melmerby]

50 minutes ago, kevinlms said:

You do realise that most of the world does NOT have fuses in the plugs. Britain is a rarity.

 

I understand that at one time the EU was looking at a way to standardise electrical fittings and decided that the UK system was "unsafe".

As most European countries seemed to have really dodgy electrics, that was politely dismissed by the UK.

[Suzie]

There is a trend to move away from the ring main anyway which is not required when fatter wire is used, and unshuttered European sockets which don't require fused plugs are allowed (probably not for long), but I think the polarised Cenelec ones used in France would be better than the reversible Shuko type used in Germany when legacy UK items are likely to be used with fuses and switches in the live only. Perhaps the blue 16A sockets might become commonplace for high power items like tumble dryers going forward.

[Coryton]

2 hours ago, kevinlms said:

You do realise that most of the world does NOT have fuses in the plugs. Britain is a rarity.

As you have discovered, it is not a fool proof solution. It only protects a fault within the device and not the wall plate.

 

Isn't the point of having a fuse in the plug that you can match the fuse to the cable going to the device? If a socket is fused, it has to be rated for the highest power permitted from the socket, but the fuse in the plug can be appropriate to the cabling.

 

Where this used to fall down was the tendency of people to put a 13A fuse in everything, but these days with everything coming with a plug already on that's probably much less of a problem.

 

The old round pin sockets used different plugs for 5 and 15 A and I don't think the plugs were fused. I don't know if the sockets were, though.

[96701]

Fuses in plugs are definitely there to protect the cable and nothing else. If a short circuit happens within the appliance, then if the fuse blows, that is an added bonus. (Unless things have dramatically changed in the fuse rating calculation criteria since I last did it.)

 

I also seem to recall that cable size was based on current flow and voltage drop (which increases current flow in the case of constant wattage loads) and the fuses in distribution boards was based on cable size, diversification and disconnection times. If one needed better disconnection times, one went to miniature circuit breakers (MCBs). 

 

It seems that nowadays all distribution board have MCBs as a default which is no bad thing because it stops people putting aluminium foil and nails in fuseholders, but I'm still unsure about the need for RCDs on all circuits. I thought that RCDs were only needed in the event of electric shock. I'm struggling to find statistics of people who have died as a result of electric shock in their home. Just a thought.........

 

[melmerby]

9 hours ago, Coryton said:

 

The old round pin sockets used different plugs for 5 and 15 A and I don't think the plugs were fused. I don't know if the sockets were, though.

In later years they were fitted with fuses and there were also 2A round pin plugs/sockets as well. All three are to BS546 and is still current!

The fuses in the 5A and 15A were the same physical size as the 13A but the 2A used a smaller one as also used for those for electric clock sockets (remember them?)

https://cpc.farnell.com/mk/641whi/5a-fused-round-pin-plug/dp/PL01928

https://cpc.farnell.com/mk/643whi/15a-fused-round-pin-plug-5a-fused/dp/PL01929

The wiring was normally radial with originally only a fuse at the fuse box only, several on one fuse.

In fact ring mains became virtually universal after the introduction of the 13A plug/socket system. Our first house had original 13A sockets when built (1954), they had plastic face plates and ceramic innards, like their contemporary 15A cousins, but all were on radial wiring.

At one time you could get 2A, 3A, 5A, 7A, 10A and 13A (possibly also 15A?) standard fuses.

I still have several plugs with 5A fuses in (ideal for devices that consume 1kW)

Edited February 11, 2019 by melmerby

[TheQ]

You can still get all those Fuses, I have the complete set 1A, 2A, 3A, 5A, 7A, 10A, and 13A in my tool box.. I'm regularly removing 13A fuses from plugs, Especially when PAT testing for shows...

13A fuses in cheap 10A cable extensions are a favourite  removal...

Edited February 11, 2019 by TheQ

[phil-b259]

On 09/02/2019 at 23:12, raymw said:

Not very sensible, and it's a bl**dy dangerous concept. You are proving a faulty socket by means of a test lamp, and not even testing the lamp before and after it's use, and advising a self declared neophyte to mess with house wiring. The only advice you can really give, in these situations, is to call in a qualified electrician. The fact that you or I may do this sort of alteration is entirely different to advising others in a public forum on how to do it. For all we know, there may be poor earth connections and and phase/neutral inversions elsewhere on the circuit.

 

In this case, you are not proving the faulty socket - you are proving the relevant ring circuit said circuit is attached to!

 

Given the use of a shielding mechanism in UK sockets, its somewhat difficult to use a multimeter to confirm the ring is isolated before remove faceplates and as such the 'lamp test' is a reasonable way of confirming the correct disconnection has been made at the consumer unit.
 

I would point out that until recently* the only way track workers knew that a conductor rail isolation was successful was to do much the same - clip a device containing 6 lamps on to of the conductor rail, clip the flying lead onto the running rail, make sure the lights lit up, confirm they have gone out when the power is switched off. (see https://www.yumpu.com/en/document/read/27590275/live-line-tester-unipart-rail)

 

Of course it needs to be remembered that filament lamps can expire so its wise not to use one for such a lamp test - just in case the lamp blows and gives false reassurance that the circuit is dead when its not (and is one of the reasons the railway version used 6 lamps)

 

Moving back to domestic wiring, it is however crucial that the person doing this understands the concept of ring circuits and how they are implemented in the domestic dwellings (which can be fairly illogical at times - particularly where extensions or other alterations have been carried out).

 

Of course once the faceplate of the suspect socket has carefully been detached then a multimeter can usually be used to confirm the circuit is definitely dead before handling / removing wires terminated within.

 

It is also good practice to not undertake such electrical investigations alone - if the worst does happen then having a 3rd party around who can administer first aid and / or summon the emergency services will increase the chances of surviving.

 

I do agree that in an ideal world, turning off the incoming supply to the entire property is the safest way of working on electrical circuits, but providing a suitable risk assessment is carried out and testing / mitigating measures are in place, then such a significant outage can be avoided. Obviously if unsure of the ring circuit design, its much safer to switch off everything via the main supply switch - but this is not always possible (or necessary). Again I point to the railway industry where its usually quite impractical to disconnect S&T lineside location cases from the 650V incoming supply when changing individual bits of equipment (without bringing the railway to a stand)  - instead individual fuses are removed as necessary with appropriate multimeter testing carried out to ensure voltages are not present on the equipment being altered / renewed.

 

 

* Now replaced by http://pdf.directindustry.com/pdf/seaward/live-line-tester-datasheet-llt/26669-154186.html - which has the obvious flaw of not being applied to the conductor rail all the time and thus giving an instant notification if the conductor rail becomes energised!

Edited February 11, 2019 by phil-b259

[Philou]

Too right! I recall many years ago, having identified the ring circuit concerned, I pulled the fuse out of the consumer circuit (days before trip fuses - RCBs?), I put an insulated screwdriver with tell-tale neon in it to undo the feed screw behind only to find a big blue flash (must have touched part of the earth plate behind) and the end of the screwdriver blown orf! The twunt before me had wired the other end of the circuit into an adjoining 5amp  fuse.

 

Take care - it's an 'unseen' danger, electricity.

 

Cheers,

 

Philip

[chris p bacon]

The only reply to this topic should have been 'Get an Electrician'

 

Some of the advice given has merit, but as most tumble dryers are located alongside washing machines in kitchen/utility areas any works in these areas should be carried out to Part P/ by a qualified person.  

Those that disagree and think just a simple lamp will suffice would have been interested in some recent works to remove a wall we undertook. With the blockwork removed there was a single socket hanging from the ceiling, inside were 3 wires, 2 were wired to the socket and one was continuous. the 2 wires were from 2 seperate MCB's (marked for 1st floor and 2nd floor in the consumer unit) and the continuous wire was a 3rd seperate live circuit (blank in the consumer unit) . Plugging in a lamp and just turning off MCB's until it went out would have still left a live circuit to be cut.  

Turning off the MCB's one at a time showed that the socket was live all the time as it was being fed from 2 different circuits so the whole lot was turned off and tested.   The issues ( there were several) were rectified and the homeowner investigated and found that the previous owner had a Father in Law who thought he knew what he was doing....

[phil-b259]

13 minutes ago, chris p bacon said:

The only reply to this topic should have been 'Get an Electrician'

 

Some of the advice given has merit, but as most tumble dryers are located alongside washing machines in kitchen/utility areas any works in these areas should be carried out to Part P/ by a qualified person.  

Those that disagree and think just a simple lamp will suffice would have been interested in some recent works to remove a wall we undertook. With the blockwork removed there was a single socket hanging from the ceiling, inside were 3 wires, 2 were wired to the socket and one was continuous. the 2 wires were from 2 separate MCB's (marked for 1st floor and 2nd floor in the consumer unit) and the continuous wire was a 3rd seperate live circuit (blank in the consumer unit) . Plugging in a lamp and just turning off MCB's until it went out would have still left a live circuit to be cut.  

Turning off the MCB's one at a time showed that the socket was live all the time as it was being fed from 2 different circuits so the whole lot was turned off and tested.   The issues ( there were several) were rectified and the homeowner investigated and found that the previous owner had a Father in Law who thought he knew what he was doing....

 

And this demonstrates the big problem in domestic situations where wiring can easily be 'altered' by previous owners / bodgers.

 

In house wired up to the mandated electrical standards (and not subsequently altered)  then this situation would not occur - hence the need to understand the electrical ring setup as actually exists.

 

If any doubt exists that things are not 'as per diagram' so to speak then extreme caution must be exercised - and complete isolations should be the norm until the electrical layout is proved (which could be done by using a 9V battery added to each MCB in turn and checking inside each fitting).

 

Having done this (and documented it) however, it then becomes possible to adopt alternative methods.
 

Edited February 11, 2019 by phil-b259

[Joseph_Pestell]

My parents' house was fully rewired by a qualified electrician.

 

Despite that, I have still found some surprises where his labelling of the consumer unit was inaccurate.

 

I would always advocate fully testing any circuit with the mains power off before carrying out any work.

[melmerby]

34 minutes ago, phil-b259 said:

 

I

Moving back to domestic wiring, it is however crucial that the person doing this understands the concept of ring circuits and how they are implemented in the domestic dwellings (which can be fairly illogical at times - particularly where extensions or other alterations have been carried out).

Ring circuits are not compulsory, radial wiring is still permissible if it is done in the appropriate way as set out in the regs. (or it was few years ago)

Ring mains should also be done in a logical way, just tacking sockets on as some "sparkies"* do when extensions have been built is also not permissible unless done correctly

When we bought this house I found a ring main on the end of a radial spur! (supposedly done by a qualified fitter)

I also found a T&E cable in the ceiling/floor void when the end was not terminated into anything and it was live. It came off some live circuit elsewhere

 

*Plenty of so called electricians about who don't know what they are doing.

(Plenty of so called building experts of all sorts who don't know what they are doing!)

[phil-b259]

6 minutes ago, melmerby said:

Ring circuits are not compulsory, radial wiring is still permissible if it is done in the appropriate way as set out in the regs. (or it was few years ago)

Ring mains should also be done in a logical way, just tacking sockets on as some "sparkies"* do when extensions have been built is also not permissible unless done correctly

When we bought this house I found a ring main on the end of a radial spur! (supposedly done by a qualified fitter)

I also found a T&E cable in the ceiling/floor void when the end was not terminated into anything and it was live. It came off some live circuit elsewhere

 

*Plenty of so called electricians about who don't know what they are doing.

(Plenty of so called building experts of all sorts who don't know what they are doing!)

 

Which rather calls in to question the chorus of those on here insisting that 'Call a qualified Part P electrician' as the solution to all electrical woes...

 

I accept that may be the 'correct' and 'official answer - but that doesn't always turn out right.

 

As regards ring mains versus radial networks - I am aware that both can be installed, but if done correctly radial circuits should not only be easier to identify from the consumer unit, but are also an easier concept for a layman to get their head around.

Edited February 11, 2019 by phil-b259