You think you have had a shock until you have the real shock

No one use fingers to find a switch wire at a pendant anymore ?

@@YGELLYPIKERno because I’m not a retard

@@YGELLYPIKER Good god yes sir... the one where i locked on and was only saved by falling off a fibreglass hopup when my legs let go... 5A non rcd'd BS3036 board, neutral switched by a DIYer sometime in the late triassic, I stupidly checked L-N and L-E ( not realizing N was actually live... and with the switch off, N-E test would've shown me 240rich chunky volts before i nearly darwinated)

2 in my life, once when I was a kid (i was into electronics from a young age) and the other a few years back when I didn't fully isolate and got a shock off a rogue boiler circuit. I now fully isolate and follow procedures more stringently.

The charge isn't for tightening the screw, it's for knowing _which_ screw to tighten.

The more I read about faults like this, the more I want to reach for my meter and start testing to make sure it isn't happening in my flat. Thing is that I have no qualifications, and having never _instinctively_ realised that NCD could happen it's reasonable to suggest that my knowledge/experience isn't nearly so good as I'd like to _think_ it is. ⚠ As it is, I had an installation test last month - Took about an hour IIRC. Is that really long enough for a single-phase mid-80s Eco-7 flat with 45 y/o wiring and tenant-declared modifications to circuits on the consumer side? 🤔

Thats not really going to do much if you have bonded pipework. The current will follow the path of least resistance and will always prefur a nice juicy gas pipe to a measley little spike. Especially when you consider that pipework will also be bonded in your neighbour's houses providing a 100% metallic path back to ground.

Where does it say that Imagine advising every existing installation they should have an earth spike installed just because

It’s recommended in bs7671 amd 2 for TNCS systems

​@@mastergx1Are not most gas pipes now plastic?

​@@roystevenson1375yes, they replaced mine about 10 years ago

To be fair, a 13A fuse will provide adequate protection against a hard short circuit (the extra energy deposited at the site of the fault is pretty immaterial, either way the item is probably a write off). That's why its generally recommended nowadays to use 3 amp fuses for low loads, and 13 amp elsewhere. For a lowish powered appliance like a fridge (150 watt or less?) I would thought that a 3 amp fuse would be more than enough, even allowing for inrush currents each time the compressor starts up. I'm old school and prefer to also protect against the long, slow overload type of fault so have swapped out my fuses for the most appropriate size like you did. I didn't swap the cables though, since that gives them an excuse to void any warranty.

No such thing as a 7amp fuse available for UK plugs

@@tonywatson1412 oh yes there is, as well as 1A, 2A and 10A. I have a bunch of all of them. Not the sort of thing you can get easily but the likes of RS and Farnell will sell you them no problem. Or these days Ebay is your friend. Really if you don't know what you are talking about it us better to keep your mouth shut rather than embarrassing yourself in public with your ignorance.

@@tonywatson1412 I will add all my C13 leads have been fitted with 10A fuses as technically the C13/C14 combination is only rated for 10A so using g a 13A fuse in the plug is dodgy

It get's a bit more complicated in the US with split phase 240/120 volt with neutral at the center tap. Under ideal conditions, the neutral conducts no current. But in practice, some current does flow in the neutral which is the amount of imbalance between the two lines leads, So if there is 20 amps in Line 1 and 25 amps in line 2, the neutral will have 5 amps back to the transformer. In a single 120 volt circuit, the individual neutral has the same current as the hot line going back to the panel. It is a bit more complicated system, but much safer because standard receptacle and lighting circuits are only at 120 volts. For large wattage circuits like a dryer or electric range, 240 volts is supplied through the two lone leads, L1 and L2. Keep in mind this is still single phase. Rather than an RCD for the whole panel, we use GFCIs on individual circuits. And where as the standard RCD trips at 3o ma, the HFCI trips at 5 ma. In the main panel in the home, there is a neutral bus and a separate equipment ground bus. The equipment ground bus is connected to a ground rod. A piece of incoming pipe can not be used for the equipment ground. However, what can get a bit confusing is that the neutral bus is bonded to the steel panel and only at the main panel, any sub panels can not have the neutral bus bonded. This is because of the possible difference in ground potential between the main panel and the sub panel. A few volts difference in ground potential between the panel location is not uncommon, but wired this way, it has no effect. The sub panel is fed with 4 wires. Line 1, line 2, neutral and equipment ground from the main panel equipment ground bus. We use TN-C-S, modified as stated above. In most cases, each home has its own transformer. The neutral at the utility transformer is also grounded with a ground rod. It is a bit more complicated, but there is nothing common from one residence to another, other than transformer primary supply . Separate neutrals and separate grounds. In theory, we use a bit more copper in the home. 12 AWG (~4 square mm) for 20 amp 120 volt circuits and 14 AWG (~2.5 square mm) for 15 amp circuits. Generally, for the same household device/appliance, we use double the current than at 240 volts. And we run at 60Hz vs 50Hz, which makes a difference in motor speeds, otherwise for most residential applications the difference in frequency is more of the theoretical debate rather than a practical one.

​@@professorg8383I didn't know it was common for each home to have its own transformer in the US. Isn't that rather expensive? And it means you have high voltage going all the way to each home, which must have safety implications.

@@thomasdalton1508 There is pretty wide variation in residential areas, But from a numbers perspective, the vast majority of homes exist in older, grid style urban neighborhoods. Power distribution in these areas is done by overhead distribution. Pole mounted transformers with short primary feeds and secondary feeds supplied overhead to the individual homes. Typical high voltage feeds are in the 7,000 to 10,000 volt range and are usually just a single phase, bare conductor across a given utility pole run. (very low cost) Many tens of millions of homes follow this basic old layout in city neighborhoods. pretty densely populated. These old city neighborhoods were built over time by individuals and not as large developments. It is not unusual to see homes that are 100 years different in age on the same streets. Most all these neighborhoods have been around a very long time. Many of them, predating electrical distribution! Rural is much the same in distribution but homes are much more spread out. In suburban areas that were built as developments across a short period of time, some differences can be seen. But in many. the overhead distribution is still dominant. In suburban areas, homes are spread out much more than urban neighborhoods, but not as widely dispersed as rural. Pole mounted transformers are pretty cheap in comparison to ground pad mounted transformers. Connections to a pole mounted transformer can be completely exposed and they are very easy to install. So if you look at total cost of installation, they are far more economical. In fact virtually none of these homes has high voltage coming to it. The high voltage and the transformers are out.on the utility pole runs along the public roads. However, in rural areas, you can find high voltage on poles that are on the private property, especially when the homes are a far distance from the road. Ultimately, these go to a pole near the home and have a pole mounted transformer on it for that home. The power company has an easement for their lines. I own a big chunk of land that has several smaller rural properties alongside it. I have 9 HV poles on my property which branch off the HV line on the county road. There are 5 separate additional services that come off that line, feeding mine and neighboring homes. (I have 3 services) Each service has its own transformer. None of the homes are visible from each other, That is fairly typical in rural areas where things are spread out. But even in densely populated urban areas, homes are far enough apart that shared transformers wouldn't be practical. It is really only in newer subdivisions that the overhead approach is not the norm and in those cases, property lots are pretty good sized, What you often see here is a pad mounted transformer for each property. But in these situations, transformers are usually near the road and fed with a buried HV line dropped from the overhead lines along the road. It then is common to have a couple hundred feet of buried low voltage lines to the house. In the end, it is far more costly to get rid of the overhead lines. The transformer may be at least 4 or 5 times the cost, plus the cost of the buried HV cable costing way more plus the installation to bury it. Then the cost to run the buried low voltage lines to the house is way more costly than overhead, So, we avoid HV lines on private property, (except in some spread out rural situations) And pole mounted transformers are far cheaper just for the transformer, let alone the installation costs. Shared transformers really only make sense in condo style homes and apartment complexes. I think that on the whole, European residential neighborhoods, are much more compact than in the US. We do still have some city neighborhoods where buildings are built right next to each other, sometimes even sharing walls. These are very old neighborhoods and there really aren't that many left. New York City is the most densely populated US metro area, but most of European cities are more than twice a densely populated. European population tends to be more evenly distributed. But the US has many vast areas of much lower population density.

Most of Europe doesn't have this problem because we must have a ground rod or multiple ground rods, the grounding system resistance must be in the single digit Ohms.

@@mernokallat645 Using common utility piping for earth grounding is a very ancient way to do this. Ground rods are cheap and easy. That has been the US standard for a very long time.

This has just answered a problem I had recently. A loose neutral on the main incomer of a 3phase DB was intermediately giving me 400 volts down to earth on L1 and 50 volts on L2 and L3. My initial thought was that it was a supply issue as opposed to inside the DB. Great to hear this from a proper tradesman. 👍

Malicious compliance

It's a function of time over conductor durability, I think. In pre-1980s properties a lot of the PEN conductors will have been made of durable grades of copper (i.e: Sized with long-term oxidation taken into account) but since then - And the continual expectation that as little money as possible be stretched across the widest area - PEN conductors will have gotten thinner, been made of suboptimal materials and/or replaced with poor substitutes (TN-C installs versus the much safer but slightly costlier TN-C-S). And it all comes down to that ancient and sacred art of „saving mon£y“... 💰⚡🔥😔

If you get a shock off of any front door component that wouldn't normally be connected to an electricity supply (If there's only a traditional doorbell, a smartlock is not very likely) - Especially in a property that gets very few visitors - This might indicate a drugs factory. Call the Police. 👍

Thank you, I love to hear how other countries' systems work. Using 1mm wire as the link is interesting and clever

@@TheChipmunk2008 I actually did it myself. I am electrical engineer, and here regulation enforcement is very loose. Redone whole main electrical distribution around meter. Before my work, there was just a 100A switch before the meter and there were 3 fuses rated at 50A after the meter. Interestingly, to the electric central heating went 5G6 cable that was fused AT THE CABLE WE END, not at the meter (it had tap off before main fuse after meter). If there was any damage to that cable (like screw or rodent) only the fuse protecting it was at the substation. That is why I have redone the whole thing. As for grounding, the top floor was PEN, lower had separated Neutral and Ground with grounding strip (house was upgraded over the years) That is why I decided to connect all ground to the local ground strip, and then make a small connection between ground and neutral just in case.

I also made an RCD fault defeat for internaly RCD protected EVSE. I use 20A bridge rectifier, connect positive and negative, and I am left with 2 anty parallel diodes in series, and I put it inline with PE. Boats use this trick to avoid galvanic corrosion, by allowing voltage difference of up to 1.2V, but still passing fault current. Then, on EVSE side I connect neutral and 'pe' with 40ohm resistor. With leakage currents up to 30mA, diode has voltage drop of 1.2V and external RCD is not tripped. But internal RCD inside EVSE would trip and not cause a blackout inside the house. And if there is big fault current, Diode by default fails short.

That is interesting@@Mladjasmilic, as you probably know from following Efixx, our main fuses are before the meter and not (officially) allowed to be touched by anyone but the power company.

@@Mladjasmilic Yes,. re: the galvanic isolator, well known to me on boats. I wouldn't have thought of this.!

Also, a capacitive shock can cause secondary injuries, ask any 80s TV engineer who got hit with the EHT and tore their hand open yanking their hand back out of the chassis....

1. They aren't bleed resistors. They are discharge resistors because they *discharge* the stored charge. 2. "Few 1000 volts." Do you mean a few kilovolts? We're supposed to be electricians, let's use the right terminology.

@@deang5622 bleed resistors was the term a few years ago... the second term might be language dependant This is kind of like them saying the ring main is a ring final'... nope, at introduction it was named 'a ring main'. A ring final circuit is a modern equivalent, and is valid, but ring main is still also valid. The one point where this has changed is earth vs cpc... (and i disagree with this change)... i think a NON earthed cpc should NOT be allowed to be g/y

Oh i've had plenty of zaps off a capacitor over the years - i'm more electronics than electrical so it's a hazard i'm often exposed to. The worst i've had was a particular big bulk cap charged to 400v DC, burnt 2 small holes in my thumb - hand smoking and a lovely smell of crispy human.

@@blower1 bet you went off sausages for a few weeks (mine was an incident with a still glowing hot camping stove and being distracted)

Probably alot of old cables and the use of 1phase supply that causes the problem. I mean, when they start making a device that breaks the PE in a EV installation in case you get a PEN fault, something is really wrong.. You should never break the PE, unless you live in the UK apparently 😅

TNC in the network but split within the installation to become TN-C-S (pretty common arrangement around the world)? That's really what the UK is doing just that they split the PEN outside of their installation on the supplier side. I'd be surprised if it was TNC all the way through.

TNCS systems in the UK do not use an earth rod. The earthing and return path back to the source is provided by the neutral line of the incoming DNO supply.

okay i see that but why not put in an earth rod in the installation cost or is it something in the rules and if you are up grading from a tt system and old rod is still in good condition when testing why do you not use it as a back up thanks for getting back to me @@deang5622

@@deang5622 From what I've seen you do have a defacto electrode through plumbing bonds and earthed items such as water heaters but not guaranteed of course since given plastic pipes appearing. At least you are moving in the right direction with the recommendation of a dedicated electrode but it's still not mandatory.

haha!

Search John ward pen fault. Very informative video

I can see that coming in future editions of BS7671 if the DNO's don't buck up their ideas

SPOT ON ,WHEN I HAVE watched welders weld on subs to main line gas mains and 6inch diameter ,fitting ovens with 1 inch supplies , they did the welding over a bank holiday ,when the factory was empty of people .

Trying to get my head around this. Why do you say TN-C-S OK on new build with all plastic services? Won't it just end up with all grounded metalwork in the house at 240V? And no RCD protection if you get a shock from that metalwork. Is it just relying on the fact that there's no good ground to get a shock to? It's interesting to see this is being considered an issue now. My house (20 years old with plastic services) is TN-C-S and I've never really liked the idea in the 20 years I've lived here, but I hadn't heard any professionals worrying about it until now.

@@AJB1 all at 240v relative to true earth, still totally ridiculous, but nobody gets electrocuted. TN-C-S tries to make the actual earth potential the bad guy

WHICH IT IS NOT, TNCS is CRAP

@@AJB1 If the new building has steel framing it has to be bonded to the earthing system. Slab foundations under wet areas, bathroom, laundry if present etc can give low enough impedance to be a hazard too so in many countries you'll find it is a requirement to bond the rebar too. Sure the plastic pipework is not conductive so eliminates that potential hazard but there's still plenty of other opportunities to get yourself across the earthing system and the physical ground in modern construction. The key thing is to maintain neutral integrity and with the apparent state of your electricity network causing faults in the network itself that just isn't happening. Monitoring with automatic disconnection of all wires may be the only practical way forward over there unless a bucket of money is emptied into fixing the network pre-emptively. It will be interesting to see how it's handled.

@@retrozmachine1189 thanks! Yes, that all makes sense. I was just wondering why @TheChipmunk2008 had said "For anything but new build with NO metallic services other than electricity, TN-S or TT should be REQUIRED", and wasn't sure why he didn't think it should be required for plastic services. Is that the shock risk being lower with grounded metal services, or the fire risk not being there as things won't carry on working but pushing current through the services? Or just that you'll notice the fault as everything will stop working?

Need maintenance, and if we start driving them in regularly we’re going to have a lot of incidents and bodged installs

@@edc1569 if it's a real issue then it needs addressing . I am sure a heavier external pen fault devise could be designed and installed such as they use with older EV chargers.

@@edc1569 I think you are worried over nothing there. Most of the rest of the world implements some form of electrode with TN-C-S systems. In Australia it is standard practice by regulations to have the rod sticking out of the ground (in a location where it is not a hazard and not likely to be damaged of course) with the earth wire clamped onto it also exposed to the elements and given a coat of zinc paint where the wire is clamped. Been this way since mid '70s. Also standard practice for electricians to check the performance of the earth stake to earth bar resistance as part of their work verification procedures, takes only a couple of minutes given they already have everything taken apart anyway.

But the electrode in Australia is so short and the wire is only 6mm² which is shocking to me. My house in Malaysia has a total of 9m long rods drilled into the soil (3× 3m rod) and the bare wire is 25mm² with pvc pipe for mechanical protection, pretty much standard here except for poor families.

@@IAmThe_RA The minimum domestic installation rod here is 12mm dia copper clad steel driven no less than 1.2m into the ground. There'd be a story behind your installation requiring an arrangement that comprehensive.

Only 9 weeks. Come back when its 9 months

Unless you have extremely low impedance on the earth rod, that doesn't solve the problem. It may reduce it, but it doesn't solve it. How much an earth rod will help with current flowing through gas mains depends on the relative impedances of the earth rod and the gas main - unless the earth rod has much lower impedance, there will still be a lot of current flowing through the gas main. If you don't have earthing through a gas or water main and are more concerned about all the exposed metal in your home becoming live, an earth rod will only reduce the voltage that everything is live at and possibly not by very much. A 230V supply with a load of 20A and an earth rod with a 200 ohm impedance (which is what people usually aim for), the earth rod will only reduce the voltage from 230V to 217V. To get down to a relatively safe 50V, you would need an impedance of about 3 ohms. You aren't going to get that by sticking a metal rod in the ground. In some countries, it is routine to bury a bare copper wire going all the way around the perimeter of the building, attached to multiple earthing rods. That's the kind of thing you need to do if you want your own earthing to protect you in the event of a PEN fault.

@fore Seek help.