Discuss Melted socket, plug and wiring in the Electrical Forum area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

removing plug from the appliances would almost certainly immediately invalidate the warranty on that nice new machine you bought!
its hard to say if there are other loose connections or terminations on the circuit that have high resistance, its possible it only showed at these sockets as they were under high load and combined with low cost / quality sockets failed much sooner.
It does look though as if the most significant melting happened behind on the cable which makes me think poor termination and contact resistance.
when the electrician comes out and tests the circuit, make sure the replacements fitted are of a decent make, Hager are a good choice,
out of interest is there much slack in the cable that can be pulled down to re terminate? as the wires look quite badly damaged.
Not wanting to step on another sparks toes as it were, I am based in central Bath and BS39 is quite a large area - you could be quite close or quite a bit out, but if you get nowhere with the electrician or want a second opinion then drop me a message. I can come out and have a look.
Thanks Gavin, I’ll give you a shout if needed. I’m Clutton. Don’t really have a choice but to remove the plug if you look at the picture in 1st post :-(
 
Cutting off and changing plugs does not invalidate the warranty. Just as well as that new machine needs a new plug now anyway.
Flex outlets are not a good idea, one reason is it makes them a pain to service.
You should not have FCUs feeding the sockets either as the plugs are already fused. If you want above counter isolation (which is not a requirement) it is best to use 20 amp double pole switches.

Thanks George. I didn’t ask for FCU, just what the sparky did (and I didn’t know any better). Maybe the electrician will change them if that would be better. Is having 2 fuses on the circuit a problem though?
 
removing plug from the appliances would almost certainly immediately invalidate the warranty on that nice new machine you bought!
You claim to be a electrician, yet your telling the OP to leave the plugs on as it will invalidate any warranty? I suggest you sell your tools and look for another career that doesnt involve using your brain.
 
You claim to be a electrician, yet your telling the OP to leave the plugs on as it will invalidate any warranty? I suggest you sell your tools and look for another career that doesnt involve using your brain.
My mistake if i misread the Op's first post, I was making the point that if the washing machine is brand new then check the warranty as some of them have some interesting clauses...
If the plug is damaged from the melting/sockets then obviously change it. but if you cut off the plug on some appliances and wire direct to a flex outlet then i have personal knowledge of the manufacturer/retailer refusing to honour the warranty as they cut the sealed plug off and used it in a way not as the manufacturer designed it.
Had a customer who had a dish washer that was playing up and currys / knowhow refused to honour the warranty as she had removed the sealed plug and used a flex outlet. maybe if she pursued the issue she might have won but currys were having none of it
 
What is the working enviroment like for these two outlets !
If it is in a laundry area, then typically it is hot and humid,
both of these factors work against long life of outlets.
Factor that in with the cheap Asian crap that has flooded the market
and it is not hard to see why these things happen.
Perhaps invest in some good quality, heavy duty, industrial type outlets. They will certainly cost more, but they will also last much longer.
 
If they are LAP or another poor quality make they won't be up to standard as I have seen so many times before
LAP & generic items sold by reputable wholesalers will be made to the same standards and EU regs as other manufacturers, they will therefore be up to 'standard' otherwise they would not be on sale. Quality of different manufacturers and cost of components is a different issue entirely. However I normally find that poor workmanship is to blame rather than material failure, loose cables in terminals etc etc.
 
This damage is caused by Ohmic heating (IsquaredR), the heating effect of a current passing through resistance. Wires, contacts, terminals, fuses all have some resistance. Unless the heat can be dissipated the temperature of an element of resistance will rise and rise. What happens tough is that as the temperature rises do does heat loss through convection, conduction and radiation so some temperature is reached when heat generated equals heat loss. Stuck behind your two machines there is also the problem of heat being generated by the tumble dryer and at times from the washing machine during its hotter cycles.

The Ohmic heating then depends on the square of the current and the resistance. Current first - the current drawn at any instant depends on the voltage of the supply and the impedance/resistance of the load. An increase in supply voltage will cause more current to be drawn. Where you live the supply voltage may be at the higher end off its range. It may also be that your PV solar system is raising noticeably the voltage off your home's wiring especially during the current long spell of very sunny clear blue weather. The same effect can be happening through other folk's pv systems if there are a number of them nearby to you and you are on the same phase. Resistance second - metallic components have a positive temperative coefficient which is a convoluted way of saying that the resistance of them increases with their body temperature. This one can have increasing Ohmic heating as the resistance rises. This is particularly so for the cartridge fuse. The poor fuse struggles in moulded on plugs to dissipate its heat because it is thermally insulated by the surrounding plastic and front face of the socket.

There is a final effect not yet mentioned by visible in the photo of the plug around the neutral pin and neutral side of the fuse. As the plastic of the plug heats up it begins to break down. Plastics are made of carbon. As the plastic breaks down regions of carbon 'track' between the neutral and live fuse because of the electric field between them. Eventually a conductive path forms - sometimes only on the surface but also sometimes within the plastic - so an electric current flows directl between line and neutral which inevitably creates Ohmic heating. I also suspect, but have not been able to confirm, that the silvery plug pins have higher surface contact resistance and higher body resistance the nickel brass pins. Last, before the use of insulated pins, the pin was of uniform cross section. The addition of insulated pins has meant that the pin's csa is much reduced along the section of the brown/blue plastic- so again more resistance and harder to dissipate Ohmic heat.

Regarding the socket. The cheap brands are often greatly stressed by prolonged high currents. It is instructive to dismantle a good and a cheap socket and compare the innards sometime. The socket has its part to play in dissipating heat. Heat flow by conduction depends on a temperature gradient. There is the equivalent in classic heat theory of thermal resistance Rth viz; H = (Tin-Tout)/Rth - I leave you to work out the consequences of this (applies to plug too). The standard method of inserting a straight length of stripped back 2.5mm2 L or N into the socket terminals may provide an adequate electrical connection but it is not the best way of minimising the thermal resistance of the connection. I like to 'Barrymore' a single conductor - that is bend it over on itself - before inserting in the socket terminal to maximise not only the electrical contact but also to help increase thermal conduction of any heat generated away via the live and neutral.

My perfect solution would be to replace the appliances plugs with black (higher IR radiation) pottery MK 13 Amp ones. I would plug these into metalclad MK 13 Amp single sockets without a switch. I would also relocate the sockets from behind the appliances to a cupboard at the side of them so that they are better ventilated, away from the heat generated by the appliances and can be kept an eye on.


A long post but I have too much time on my hands at the moment!
 
My mistake if i misread the Op's first post, I was making the point that if the washing machine is brand new then check the warranty as some of them have some interesting clauses...
If the plug is damaged from the melting/sockets then obviously change it. but if you cut off the plug on some appliances and wire direct to a flex outlet then i have personal knowledge of the manufacturer/retailer refusing to honour the warranty as they cut the sealed plug off and used it in a way not as the manufacturer designed it.
Had a customer who had a dish washer that was playing up and currys / knowhow refused to honour the warranty as she had removed the sealed plug and used a flex outlet. maybe if she pursued the issue she might have won but currys were having none of it


I did some extensive research sometime ago about moulded plug tops and white goods or kitchen appliances. I emailed several of the major appliance manufacturers, asking specifically if removing their plugs from their appliance leads would invalidate their warranty, and posted their replies in a thread. Only one replied back that it would. Unfortunately, not being a full time researcher, I never booked marked my thread, and my PC with their emails went u/s :rolleyes:, so I can't remember or say who that was. I did install a Bosch appliance recently, and the instructions stated that only a Bosch replacement lead & plug should be used, if the original was damaged. So I guess, reading the product manual is important, before making this decision.

Notice, I never suggest you sell your tools :)
 
LAP & generic items sold by reputable wholesalers will be made to the same standards and EU regs as other manufacturers, they will therefore be up to 'standard' otherwise they would not be on sale. Quality of different manufacturers and cost of components is a different issue entirely. However I normally find that poor workmanship is to blame rather than material failure, loose cables in terminals etc etc.
Regardless of whether they are supposedly made to the same standard I have seen LAP sockets fail out of the packet, they have a cheap feel to them and are definetly not made to the same standard as more expensive ones. Maybe fit for use, but definetly don't have the same life span
 
Cheap accessories will be made to, and pass the relevant standards, however they'll just pass whereas more expensive accessories will normally greatly surpass the relevant standards.
 
Yes, both good, although many would argue they aren't what they used to be.

Looking at the pictures of the socket backs, it's impossible to say with certainty whether the burnout was caused by poor quality socket contacts, or bad workmanship by the installer. Because they are unswitched singles, the terminals and socket contacts are joined directly together and heat flows readily between the two. Also, the burnt line conductor was pressed against, and melted into, the back moulding directly above the contact. But there are hints that the heat was generated by loose connections rather than slack contacts. Bad workmanship may well be the root cause, but there can be other factors such as excessive thermal cycling of the terminal due to the heating of poor quality, high resistance contacts.

Re. cutting off plugs, there is a UK-specific instruction that used to be standard, maybe it still is, I haven't noticed recently, advising users that if the plug didn't match their socket outlet, it should be cut off and destroyed, a suitable plug fitted and the correct fuse fitted in the DB. It's a hangover from the days when there were still some round-pin and non-standard sockets in use. There are still situations where that applies (clean-earth supplies in commercial buildings with T-earth variant BS1363 sockets etc). It would be ludicrous if removing and replacing the plug with one of the same type invalidated the guarantee, while fitting a different type did not.

Re. causes of plug heating, while all of Marconi's points are valid, in practice some of them are much more important than others and some can usually be discounted. The greatest variable, the contact resistance, trumps all the others under bad conditions.

Somewhere near the head of my list of things for the new video blog will be stuff about heating in contacts and terminals. In 1882, Musgrave Heaphy who wrote the first wiring regulations, the Phoenix Rules, was aware of how often bad connections caused fires. 136 years later we are still struggling to get to grips with this.
 
All of this suggests that putting the sockets for high-power appliances above the work surface where they can easily be seen is a sensible option.
 

Reply to Melted socket, plug and wiring in the Electrical Forum area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

YOUR Unread Posts

Electrical Forum

Welcome to the Electrical Forum at ElectriciansForums.net. The friendliest electrical forum online. General electrical questions and answers can be found in the electrical forum.
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock