Buzzing Mains Socket

SOme LAP gear is amazing value and any issues Screwfix just replace or refund

LukeD said:

SOme LAP gear is amazing value and any issues Screwfix just replace or refund

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I must say I was quite surprised fitting a LAP outside LED wall lantern the other day, well designed and made of metal and glass!

hi guys... appreciate continued support.... ?

i support electricians and plumbers in my "day time job" (maintenance op), so am familiar with some of the ins-and-outs of fault-tracing...

i keep away from "live working" on mains voltage (of course) since I dont have any training to do so. rather i fix and optimize low-voltage stuff like pc & laptops. i know my way around printers, too. (my qualifications are in software engineering)...

i am a bit of a supergeek, so I take an interest in equipment and techniques to solve problems.. i dont have pro-level wire strippers, a socket tester, or a replacement socket, but it makes sense as @pc1966 pointed out to fit a good brand.

here's some pics of my setup, for those interested...

I noticed - on the tenby socket pic, there appears to be carbon-burns on the top pin (earth terminal). experts on the forum may find this interesting....

as @FatAlan points out, the socket circuit should be isolated immediately.

in andy's (pro) vid, he simply locates the CU switch that turns off sockets, then tapes it down... since only "tenby socket" is buzzing I'll fit a cover over the pins and count my blessings I don't have three teenage kids, a wife and two dogs living with me

my CU unit is pictured.. looks like the newer type to me (this flat isn't very old, thankfully)... curiously, i cant find the model of my CU online. it appears to be:

Wylex MSPF-4587 (although I might be reading that wrong, cant see a model number...)

as you can see, "sockets circuit" is clearly marked... there appears to be six circuits in all (which I'm guessing is fairly standard in smaller, modern properties).

as @pc1966 points out my landlord may require only certified electricians to work on their properties. at this stage (sunday) i cant actually contact anyone to report this fault... I am hoping I'll be able to talk to a real person, who'll give me a real date when a real sparks can take a look at this

at this stage, I don't have the test equipment to ensure "dead working" and pro-level strippers to re-terminate the wires (that may be damaged) - i know there's various methods of doing this...

if anyone (outside the trade) gets this far, I'd highly recommend only reviewing vids by qualified electricians (there's a few on youtube that give the impression it's a three minute job) but I noticed a lack of:

circuit testing (to ensure dead working)
precautions to stop a circuit "going live"
correct termination and shielding of wires (to prevent future arcing)
no discussion of better socket brands available

regards, nb

Spot on there mate. Good to see someone listening to advice and not just bowling in, and looking for it afterwards…..

Ie “where does this cable go?”


The black may be carbon as you say, but think about the earth pin only carries current when there’s a fault.
im thinking it’s simply wear and tear…. Not the socket but a double insulated appliance with a black plastic earth pin on the plug. The black is rubbing when the plug is inserted/taken out and leaving residue on the socket. (I might be wrong there)

actually. Does the buzz happen only with one particular appliance? Maybe check the plug for a loose connection, if it’s not a moulded on type.

littlespark said:

Spot on there mate. Good to see someone listening to advice and not just bowling in,

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appreciate the recognition. it's a learning curve with mains electrics. ? talking of which....

found GSH Electrical vids, kindly mentioned by @FatAlan

GSH demos correct:

wiring re-termination (including establishing conductor-depth)
grommets
pre2004/post2004 mains wiring color codes
use of pro-level wire strippers.

for apprentices (or super-geeks like me) I'd highly recommend.. he is very thorough. interestingly, he doesnt get as many youtube views as the DIYer "tutorials" (which I find quite worrying) I guess people have to engage their brain cells with this kind of repair.

at one point, GSH finds a double socket with both types of mains wiring (this is where less knowledgeable fitters may come unstuck)... so I'll post a pic for reference

littlespark said:

im thinking it’s simply wear and tear…. Not the socket but a double insulated appliance with a black plastic earth pin on the plug.

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its a good point: i decided to check plug on the vac... it doesn't have the black plastic pin (i know what you mean)... checking inside, connections are tight, but I found my 1400 watt vac has no earth wire... not sure what to make of that? ? 1400 watts doesn't sound like low-voltage to me... [pic attached]

littlespark said:

Does the buzz happen only with one particular appliance?

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..once socket started buzzing, i've kept it powered down. (i think you guys are right, its a high voltage arc and probably a fire-hazard). i only use it for vac occasionally (since its low-mounted in hallway). but now i'm thinking if I plug anything into it there's gonna be fireworks! ?

my assessment is "wear and tear" too, so a swap out for a new one seems like a safe bet, i just hope my landlord agrees

regards nb

Vacuum cleaners are normally Class II and do not require an earth. They will display the square-within-a-square symbol on the data label. It is easy for manufacturers to make vacs Class II because the motor is buried within the machine, and advantageous not to rely on an earth because vac power cables often fail with internal breaks through repeated flexing and the earth core continuity can become suspect.

Socket buzzing only under load - bad connection or bad contact arcing. Check cables correctly inserted into terminals and tighten terminal screws. If problem persists, change socket. Simples.

nbwriter said:

appreciate the recognition. it's a learning curve with mains electrics. ? talking of which....

found GSH Electrical vids, kindly mentioned by @FatAlan

GSH demos correct:

wiring re-termination (including establishing conductor-depth)
grommets
pre2004/post2004 mains wiring color codes
use of pro-level wire strippers.

for apprentices (or super-geeks like me) I'd highly recommend.. he is very thorough. interestingly, he doesnt get as many youtube views as the DIYer "tutorials" (which I find quite worrying) I guess people have to engage their brain cells with this kind of repair.

at one point, GSH finds a double socket with both types of mains wiring (this is where less knowledgeable fitters may come unstuck)... so I'll post a pic for reference



its a good point: i decided to check plug on the vac... it doesn't have the black plastic pin (i know what you mean)... checking inside, connections are tight, but I found my 1400 watt vac has no earth wire... not sure what to make of that? ? 1400 watts doesn't sound like low-voltage to me... [pic attached]



..once socket started buzzing, i've kept it powered down. (i think you guys are right, its a high voltage arc and probably a fire-hazard). i only use it for vac occasionally (since its low-mounted in hallway). but now i'm thinking if I plug anything into it there's gonna be fireworks! ?

my assessment is "wear and tear" too, so a swap out for a new one seems like a safe bet, i just hope my landlord agrees

regards nb

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The 1400 Watts has no bearing on low voltage. 230V is classed as low voltage.

And the voltage or wattage has no bearing on whether the item will be Class I (ie earthed) or class II (ie not earthed).

In your circumstances I'd ask your landlord if you can turn power off and have a quick look, obviously noting advice earlier in this thread about safe isolation.
People with far less respect for electricity have ploughed into bigger projects!
Having loosened socket and gently pulled forwards, try and get an early sense whether the wires look to be in good condition, with good insulation, and are properly in the terminals.
See if any of the terminal screws can be nipped up.
If it instantly looks like a can of worms don't get too involved, no shame in pushing it back, leaving circuit off and getting landlord to get a sparks in.

timhoward said:

People with far less respect for electricity have ploughed into bigger projects!

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yeh without getting too specific... I've met a few ?

one fella (at managerial level) asked me to open up one of the old CRT monitors. The capacitors in these hold charges for weeks... the high voltage flyback circuit carries a load of 20,000v ... Once I learned about this, I realized the old skool TV engineers were some of the bravest persons on planet earth...

although there's ways to discharge capacitors, I am no expert at this. they do crop up everywhere, though, in old lighting circuits and dishwasher machines. (in my world, they're hidden in power supply units (for pcs) I've never fancied disassembling one (on the basis I don't really know how to ensure dead working, or correct capacitor discharging)...

I could isolate mains supply (cu shutdown main red switch), pry socket off wall (gently) and see if it's anything obvious.. (most tutorials recommend taking a picture of it "in situ"). without a basic tester, though, I'm pushing my luck.... a basic probe-type multimeter feels like a good idea in this case. ?

the "class I & II" categories (for appliances, I guess)? are new to me... thanks for mentioning. I'll have to research this to get a firm grasp of what's going on: the vac (although it wasn't expensive) hasn't failed me for years, but you can easily describe me as a "careful owner".

regards, nb

CRT monitors and TVs can hold capacitor charge for years, never mind weeks.

I’ll get my old 12” portable out the attic and give it a go ?

littlespark said:

CRT monitors and TVs can hold capacitor charge for years, never mind weeks.

I’ll get my old 12” portable out the attic and give it a go

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certainly.... (i've heard people say capacitors dissipate charge slowly when disconnected), but that feels like guess work to me. with these kind of things, you've really got to "know your onions" (as they used to say)...

the old CRTs are worth studying for those with a deeper interest in electronics... components like flyback circuits and "condensers" are highly ingenious. I kept one of my old CRTs as a "research project" ... if I can understand whats happening in that device (electronically), I can understand anything ?

regards, nb

nbwriter said:

certainly.... (i've heard people say capacitors dissipate charge slowly when disconnected), but that feels like guess work to me. with these kind of things, you've really got to "know your onions" (as they used to say)...

the old CRTs are worth studying for those with a deeper interest in electronics... components like flyback circuits and "condensers" are highly ingenious. I kept one of my old CRTs as a "research project" ... if I can understand whats happening in that device (electronically), I can understand anything ?

regards, nb

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The lectromagnetic deflection of the CRT beam is fascinating. Also, look up oscilloscopes and what they can show you about what is happening in a circuit - I think you'll find it interesting.