The Hidden Danger in your Cut Out Fuse: Don't ignore this!
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- Опубликовано: 8 июл 2023
- It resembles a scene from Clarkson's Farm, but Eddie struggles with phenolic degradation. No, it's not a contagious disease., It's a serious problem which affects older-style electricity service cut-outs. Dr Gary Hayers investigates with the help of Eddie's trusty contact voltage indicator.
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Make sure your Safe Isolation knowledge is up to date.
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Just as he said, "As you can see, it's not contactless" the test instrument lit up when he touched the double insulated meter tail, which suggests it's picking up induction and not surface voltage.
i laughed when it lit up aswell and thought the same thing lol
actually a lot of these testers go off with movement, im not sure why but even some fluke testers do it and im not sure if its atmospheric residue or a generated affect from the kinetic force of the movement. otherwise it could also be a dual function tester with contact pins at the tip for surface voltage, and prob shaft for induction
I once had a cobweb light up and at first I thought is a spider web conductive. I very quickly realised them testers are crap. Can’t beat a avi
@@ASHLambretta I love the way you electricians understand this mysterious science that the rest of us find unfathomable. It’s like you’re in some secret society.
@@BritishJax absolutely right we call them widowmakers over here in the the only thing I really trust them for is to let you know that you do have energized wires that's it
Thank you so much for putting this video up, it could save someones life one day.
I was in my cabinet today and noticed something wasn't right, I had my Fluke T150 with me and noticed the service head and carrier was causing it to beep and light up the voltage present indicator when touching the head or carrier. I ran inside and grabbed my Fluke 87V and I am seeing in over 30V on the head and carrier. I called the DNO who came out in 30 minutes and confirmed the issue. He changed the carrier to one he had on the van and the reading dropped to 1V on the carrier which proves both my carrier and head is suffering phenolic degradation, as the head itself is still reading 30V+ but not his carrier. Now the Fluke 87V has an impedance of 10Megohms so this leakage is very low current but the voltage could be a lot higher under higher impedance and certainly an indication of phenolic degradation which may progressively get worse.
The man from the DNO had not come across this issue before and was really interested, he has logged and reported it and will discuss it with his colleagues. I think someone will be back to replace the service head/cut out.
Hopefully there is more awareness of this as although I am personally familiar with things like phenolic degradation and materials becoming hygroscopic. I would never have thought about this with the service head and I dread to think what could happen to someone removing the fuse carrier, accidentally brushing past a degraded carrier/service head when reading a meter or switching off an isolator.
Pleased we’ve been able to help - thanks for sharing your experience 👍
Update…..
UKPN (UK Power Networks) turned up this morning to check out the service head. It is being booked in for a replacement.
Great to catch up Gary, see you again soon.
👊😎👍💙
Thanks for the update 🦾💕🦾
As a consumer you would *never* think that such a thing could happen. _Plastic is plastic_ and _plastic is an insulator_ means most (Myself included) might think _Once an insulator, always an insulator!_ 😳
My supply has a ~40 year old service head on it, so part of me is wondering if I really should get my voltmeter out?... ⚡
A very informative video, I remember my family home ,our electrical panel had pull out blocks for the main and range cartridge fuses which were made from bakelite. 100A 120/240V 240V dryer was fused into the opposite phases of the plug fuses at the bottom of the panel. There was a six circuit fuse box in the house, probably an 8-3 BX cable off the power lugs at the main panel. House was built around 1946-49
Back in the 90’s when digital multimeters were just becoming affordable you couldn’t get a reliable reading from them due the very high input impedance in factories where cables were running alongside other energised cables. They were as much use as the trusty neon screwdriver😂😂. ( very popular in the day) you could easily be showing 100v on a circuit then read it with an old style meter and it would be zero. Sure as hell wouldn’t worry about 10 volts. Do they still teach apprentices to use the back of the hand for to first contact after testing??
Thanks Gaz .. these short onsite clips are AMAZING for learners. Keep ‘em coming 🦾❤
Thank you for highlighting this problem. Once again another great video gentleman
I think that this is the most important thing I did learn today.
Wow, very good video. Have only ever seen this happen on a switch. So a reminder it can happen on any piece of equipment
Nice video!
I am in my first week of my DEI course, and this type of thing educates people like myself to act safely.
Thanks 💪🏽
Thanks for watching 👍🏻
Wow you learn something new each day. I had no idea this was possible with black service heads.
Thanks for the heads up guys.
👍🏻
I did not know this was possible. Sharing this to my Facebook, and making people aware. I had something like this in a Place for People property.
You didn’t know it was possible but you also had a similar problem?
You "had something like this"
What can be like this ?
We better start bonding the service heads then 😂
😂😂😂👍🏻
Before bakelite, they used to be metal.
This shows why we do IR tests on our side of the cutout equipment to see if there is any breakdown in resistance through ageing of bakelite in accessories etc. The actual voltage from the fuse carriers shouldn't be an issue for us as we aren't allowed to pull cut out fuses anyway, this just adds another reason to the list like electric shock , explosion and severe burns .
Could become an issue for anyone working near the cablehead if the phenolic breakdown causes a short between phase and neutral. This has happened before, guy I used to work with got burns on his back as the cablehead behind him flashed over while he was working next to it. Fuse had not been pulled
Great video guys, food for thought there. What’s the probe model number??
Thankyou, possibly saved my life.
What did they put in your phenolic or Bakelite to make it leak a few milliamps @ 250v ? Metal impregnated resin?
I saw the E5 group talking about this a while back. It is a very interesting phenomenon. The plastic gets cooked with time, heat, UV and then it starts to break down and corbonise. Once it starts to carbonises the current can start to flow through it, the more the current flows the more carbonises. Thus over time it accelarates making it worse.
The DNO/DSO are well aware of the issue and they are well aware of how many service heads they have that are not GRP (glass-reinforced plastic). The question that should be asked is
Why are they not being pro-active and have a upgrade program in place?
The Electricity at Work Regulations 1989 section 4a should cover it. While the DNO/DSO are there they need to fit an isolator as well.
What is a section 4 of the electrical safety regulations?
(4) Any equipment provided under these Regulations for the purpose of protecting persons at work on or near electrical equipment shall be suitable for the use for which it is provided, be maintained in a condition suitable for that use, and be properly used.
In my opinion the reporting and possible checking of a service head should be included in BS-7671AM3 (AM3 I understand is already on way)
Mate thanks for that informative explanation, they should have explained how this happens in the video!
It's more a reaction with oxygen, and the ability for the plastic to build-up carbon upon it. It starts to track. The only foolproof units are ceramic - but there's a significant cost disadvantage to them.
Insulation resistance is dropping, probably due to moisture absorption, like old cable.
Them pen testers pick up tiny bit of voltage and you’ll always pick up voltage on the sticker and tails 😂😂
Why bother with the (unreliable) unipole device when you have the dual pole voltmeter where one pole is grounded - giving accurate readings?
That's very useful to know.
Is there a maximum allowable voltage before the DNO will act?
That explains why mine now has yellow tape all over it. No surface voltage though.
Slightly concerning that the fault codes managed to be "hot", "weakened", & "damaged" before someone thought of oh yeah *"actively on fire right now".*
Do we know what sort of timescale this degradation occurs?
Never knew this was an issue. Just checked the 40-year-old black service head in the nice dry attached garage here and there's no measurable leakage.
What is the make & model of the voltage tester (pen type -contact voltage tester) ???
Cheers guys 👍
Where can I get that touch voltage meter?
What sort of installation year going back in time is it that installs will start to suffer from this?
What kind of pen tester are you using? Name of brand please
Thanks for adding actual captions for the Deaf.
So weird seeing this in Australia, we would have to have mains mechanically protected.
Nice to see 20 year old phase coloured tape still stuck on. Modern tape starts to peel off after a few hours.
Great another problem to look out for as well as transient voltages on your earth cable
Exactly what I thought... this is nightmare
yeah? A 5v reading nightmare lol
The dno fitting a double pole isolator the other week told me this that the old cabe head the black ones are starting to degrade & thay have been warned to double check the old black cable heads for voltage leak must be quiet a common fault...👍
DNO wont be replacing anything with just 5v surface voltage.
ive found 80v and that was considered worthy of thier time, anything under 12v, they ignore
Outdoor temperatures and condensation cause spurious Voltages on the older Black 3 TPN Service Heads hence the move by the DNO's to the Grey Injection Moulded variants
Shock horror, there’s a few microamps of leakage current through a 50 year old phenolic 3:49 insulator. Better not lick it then.
Stupid comments like this need a fully sarcastic clap-back.. I just can't be bothered with it though.
Assuming the input Z of that meter is 10M ohms, that's 10V / 10M = 1uA. Nowhere near enough to even feel it. I assume there's been occurrences of people actually getting a shock off these which has lead to this being reported? If they're simply grounding one end of a DVM and sticking the other on the service head, they're bound to pickup AC voltage. You would get exactly the same if you placed the probe next to any of those tails.
On 3:36 , someone has reported electric shock with more than 50V reported
Just to confirm my assumption re the input Z of that meter, it's actually quoted as 7.8M ohms on the Megger datasheet, so still VERY high and bound to pickup AC voltage readings if in close proximity to live parts.
@@FlyingPlastic356 He mentioned that 50V was reported, not a shock specifically. 50V if measured with most standard DVMs will equate to a current in the region of 5uA. That level of leakage in itself is not going to cause any issues. I'm not saying that heads don't fail in this way, I just don't think using a high Z meter is the best way to measure it.
What are you on about? What does the meter impedance have to do with the ability to shock?!
@@aidensmobile614 A lot. Although the meter may show 50V AC, that's only at a VERY low current. If you measured that same voltage using a low Z meter, you'd get a much lower voltage reading.
The DNO as so concerned about it that they're going to do nothing about it and just back heal until us, as electrician do all their inspecting for them.
Looks too much like a volt stick and for that reason I don't trust it 😂
I have pulled 100s of these with my bare hands over the years and never even felt a tickle once. Is there any stats/record of incidents on this subject?
I think I remember the DNOs were using de-sensitised volt sticks to presumably eliminate false alarms. Get out the test lamps and a neon!
@fluxington I think for what it's worth il just give them the old 40ms quick finger from now on to be on the safe side 🤣
@@davey6024 Same here, bare hands on cut out changes, don't trust this at all - and I've felt induced voltage on not live conductors.
This has been an issue for a few years now, generally this type of cablehead change is reported by the metering companies when a new smart meter is installed.
The issue can be aggravated if the equipment is located in a damp position as in an outside cabinet.
When working on this equipment ,in date , certified rubber gloves need to be worn by authorised personnel to insert and withdraw fuses.
If you are an electrician who will be doing work where a new meter will need to be fitted it is worth your while scoping out the job and reporting it smartly. The actual work of replacing may well need to be put on the DNO works program and could hold up your plannned installation works .
Interesting, that looks like the KT1700 single pole tester which operates between 50-600 volts which is odd considering the voltage measured on the DMM.
Induction as there is probably a load on
VT7’s will pick up voltage even if there’s no surface voltage, best way to check for stray current is with a Drummond test lamp
Yes totally agree with you I would do the same Exact procedure like you just said in the comment 👍
Definitely I can tell you’ve worked on cutouts and exchanged electric meters before pal 👍
Oooh free voltage. Nice.
What are those little nut shells seen in bunches on the floor, anybody ? I sometimes see them and wondered what they were and how they get there ?
Found 3 supplies with this issue at work after watching this video. Had national grid out, engineer had never seen problem before and phoned his manager, manager told him this is normal????? I was getting 30VAC on one of the fuses so doesn't sound normal to me.
Wow I never new this was such a problem.
What was the test probe he was using? And can a normal non contact voltage stick be used.? Also is his multimeter a standard model a perceive for this test ? I have just tried my non contact voltage stick on my cutout and with a bit of pressure it’s lights up .fantastic video Gaz as always 👍👍
No a non contact volt stick can't be used by definition it's not contacting anything. It's merely works on induced voltage through the magnetic field from the voltage present. Any volt meter would read the leakage voltage through the bakelite.
a non contact voltage stick will ignite just when close enough on good equipment so no good in this case
@@dennisphoenix1thank you
@@radiotowers1159thank you
@@dennisphoenix1a normal everyday multimeter would do ?
What impedance meter do you need to measure these sorts of voltages?
In this video the breakdown is so small, that it is barely visible at 10MOhm input impedance (on the megger), it even has to struggle with ranging.
It will not even show with LoZ-measurement or electrical testers.
Capacitive EF-Testing with insulating eqipment as demonstrated is nothing that I would deem reliable measurement....... ;-) ... It'll pick up everything from moisture to moon phases.
Don't get me wrong. If there are readings, it should be replaced. But 5V at 10Mohm is nothing that sparks immediate panic in me.
Its often a result of heat damage to the glue that holds everything together which then allows moisture to be absorbed so if theres any sign of overheating stay away
5 V at 10 MOhm input impedance of the DMM... Obviously the insulation is not great and it might be a good idea to replace it, but how is that an immediate danger?
Also, since when is the EF-detector trustworthy, especially if you are wearing lot's of insulated protective gear that is further messing with that capacitive measurement method?
So electrician is surveying for the DNO?
Yeah, but you can't touch the service heads 😁
nice !
Never seen a19 code 😮 and I am mocopa trained
watched all the ads through, just for you! 😂
Aren’t those rubber gloves meant to be worn underneath leather gloves?
The leather gloves would be enormous! But if I remember correctly, there was a pair of cotton gloves that were meant to be worn under the rubber ones. No-one used them because if you wanted to use a neon, you would have to remove part of the rubber glove to get skin contact. In my day it was test lamps and neon for proving.
Fine, just don’t let them insist on installing a smart meter at the same time! Opt out.
👍🏻
Why tho?
@@Trident_Euclid as far as i'm aware the issue is that they dont smooth out spikes in usage so normally end up giving a bigger bill.
i have seen someone reported being charged for using 8GW because the meter crashed
@@smeegle If that's the case then surely there's a problem with meter certification.
Because smart meters have a great big cutout contact in them which means the DNO can cut you off via wireless instead of a court order.
Also they will end up "load shedding" in the future as renewables don't work reliably enough, which means the smart meter will cut out to save the grid
Interesting, I wasn't aware of this issue. Having said that, 10 volts into a high impedance test meter doesn't sound like an issue; the real test is how many milliamps would leak through it to a human. Might be worth trying to measure the current its capable of passing to earth.
As the voltage is only 10V measured, it won't be enough to break down the natural insulation of the skin so no current will flow. Only when the voltage exceeds 30V a.c. RMS or 50V d.c. which is considered hazardous is there likely to be a risk of shock and current will flow through the skin. Assuming just a minor breakdown of the insulation, the current would likely be limited but there's no way of telling and it could be very dangerous especially when it's likely been subject to overvoltage transients on the line which would stress the insulation.
In other news, since the release of this video Marigold's sales have been sky rocketing in supermarkets near you🎉😮😅
If this is a known thing why are they not replaced as a matter of course while fitting smart meters along with isolation switches and dare I say SPDs? Could use some that massive profit or excessive standing charge to pay for it.
I take the max voltage would be 230 v ?
The single phase parameters are 230 v , plus 10 per cent, - 6 per cent. 217 v to 253 v
that's free energy that doesn't go through the meter
bakelite.....world needs more bakelite
I would say that is induced! Not a breakdown in the insulation.
O heck that's not good ..better be extra careful pulling the fuse then 😮
Thats most the panels I work on now ####d as comapny i work for still have these not even thought about the brake down of the phenolic resin
Well time for upgrades 😂😂😂
under 50v its not dangerous ???
Seams a bit over the top for 10v ac
So this plastic is an electrical conductor??
Phenol is involved in making bakerlite heat resistant plastic. Phenolic breakdown can cause electrical conductivity. When an air bubble bursts between carbon fibers, the carbon fiber braid breaks up, causing electrical resistance in composites.
Surely this is a massive issue? I mean there are millions of these things inside of people's houses - often under stairs and well within touching distance
It all depends on the actual composition of the cut out. The different manufacturers would have slightly different mixes to make the product. Also the older cut outs were thicker walled so more resistance. If the cut out isn't overloaded or running at high load for extended periods the degredation is far slower due to lower temperature. Car charging might make the issue worse with 7kw loads for long periods of time. Who knows
No, it doesn't matter. When you smell bakelite burning you would have weeks before it'll go on fire. And you can't feel 5v - if that's real.
wait, the power meter same like mine and I live in asia
Companies make products for international markets.
DNO C17, they might change it in a few years ahah
Used to be an E88.
I had a meter change on site. The guy pulled the fuses and got a electric shock from the head.
Silly bugger. Worst I've had is a dead short!
By the 19th edition im sure this will be another dno problem that has become our problem... Mobilise all your free operatives to identify issues on your network. Keeps the shareholders happy... But you'd better not pull that service fuse chaps or there will be trouble. 🙄
The service head fuses fall out all the time! Funnily enough, they only do it when I need them out.
@@paulmatthews5470 likewise. People keep banging on about seals. Never seen one in my life.
so touching the fuse with the back of your hand is no advisable then!
Who would have believed it .
Please blur out the meter numbers and MPANs as those with access could identify these premises. Cheers J
What could you then do with that knowledge?
@@12000gpReport the fault 😂
@@AntonyoKnight 😂
Most dangerous thing about electricity is showing people what to do on youtube ,i am an electrician over 40 years if someone wants to know call an electrician or go to trade school learn .
So thats why the local DNO in every region of the UK is going around and fixing the deadly pre known problem, FFS
So like 10 volts. Jesus. You could lick that and not feel a tickle. I thought 12v SELV was safe to touch?? And then you state a touch voltage of 50 volts is the danger cut off???
This shows why electricians shouldn't be touching or pulling cut out fuses. Simples.
I’m not convinced. Sumots not right with his test pen.
I do the same thing. Called DNO out and they used a none contact voltage detector followed by yeah it’s fine. Absalute joke
What would happen if say the same DNO staffer was say installing an isolator and pulled one of them service head fuses and getting a shock of however many volts is leaking from them?
Yes electrical installations don't last forever. Untrained people think a property wired in the 1960's or 1970's will be fine, not so it breaks down over time, ergo periodic testing
Thank you Eddy! Cows safe just now then. Even I cringed just then. 🫣✌🏻👍🏻🇬🇧