Yesterday I passed SFS6002 electrical safety course and got SFS 6002 käytännössä book. SFS 6002 electrical safety training is for all electrical work in Finland engaged in compulsory education, which must be renewed every five years. Now I know somewhat more than before on electrical safety related to electrical installations.
SFS6002 is a Finnish standard how electrical work should be performed safely. It is based on European general standard EN 50110-1 (Operation of electrical installations – Part 1: General requirements) plus Finnish national additions to it.
If you want to get your hands on the original European EN 50110-1 standard, you need to buy it. There are also free information on standard available: British edition of the standard BS EN 50110-1:2004 can be found on-line.
771 Comments
Tomi Engdahl says:
IEC Protection Classes for Power Supplies
Power supplies fall into one of three protection classes based on the need, or not, for a protective earth connection:
Class I – where user protection from electric shock is achieved through a combination of insulation and a protective ground.
Class II – where user protection from electric shock is achieved through two levels of insulation (either double or reinforced)
Class III – where the input is connected to a safety extra low voltage (SELV) circuit meaning no further protection is required.
Tomi Engdahl says:
IEC 62368-1
An Introduction to the New Safety Standard for ICT and AV Equipmen
https://www.cui.com/catalog/resource/iec-62368-1-an-introduction-to-the-new-safety-standard-for-ict-and-av-equipment.pdf
As a single harmonized safety standard, IEC 62368-1 has been the work-in-progress of IEC
Technical Committee TC108 since 2002. It is worth noting that TC108 is also responsible for
IEC 60950-1 and IEC 60065, and has implemented changes in the latest editions of both to
ease the transition to the new standard.
Currently, then, the 62368-1, 60950-1 and 60065 standards are active in both North
America and Europe. Although the situation may sound complicated, the standards have
been allowed to coexist to help the industry transition to the new standard as smoothly
and cost-effectively as possible.
REASONS FOR THE CHANGE TO 62368-1
As a unified replacement for 60950-1 (for ICT equipment) and 60065 (for AV equipment),
62368-1 represents more than just a merger of the two standards. The move is the latest
evolution of Hazard Based Safety Engineering which has become the new approach as
new types of affordable products have emerged for use in small and home offices, and for
home entertainment.
With continued development of new technologies and new markets, the distinctions
between AV and ICT equipment have become increasingly blurred – multimedia products
provide just one example. A single harmonized standard aims to give a clearer framework
to evaluate the safety of these products
In addition, 62368-1 plans to give product designers more flexibility, in product design and
evaluation and to keep pace with technology without requiring frequent (expensive and
time-consuming) revisions.
SCOPE OF THE NEW 62368-1 STANDARD
62368-1 applies to all equipment currently subject to 60950-1 and 60065 safety standards,
and further products are to be brought within its scope.
Clause 1 describes the scope of the standard, while Annex A contains a list of product
types covered. Currently, these include:
●
Computing and networking products such as servers, PCs, routers, notebook/laptop
computers, tablets and their power supplies
●
Consumer electronics such as amplifiers, home theater systems, digital cameras and
personal music players
●
Displays and display units including monitors, TVs and digital projectors
●
Telecommunication products such as network infrastructure equipment, cordless and
cell phones, and similar communication devices, including battery-powered devices
●
Office appliances like copiers and document shredders
●
Various other types of audio/video, information and communication technology
equipment used in homes, schools, data processing centers, and commercial and
professional environments
HOW THE SCOPE OF 62368-1 AFFECTS POWER
SUPPLIES
62368-1 applies not only at the product level but also – where relevant – to components
and subsystems. This is the same situation that prevailed under 60950-1 and 60065, so
companies that source third-party subsystems such as power supplies should inquire with
the manufacturer to establish if the product is currently or has plans to be certified to
62368-1.
An important – although, it must be noted, temporary – provision is the sub-clause 4.1.1,
which enables companies to continue using their inventory of 60950-1 or 60065 parts in
products certified to 62368-1. The clause states:
“Components & subassemblies that comply with IEC 60950-1 or IEC 60065 are
acceptable as part of equipment covered by this standard without further evaluation
other than to give consideration to the appropriate use of the component or
subassembly in the end-product.”
Readers familiar with the requirements of 60950-1 and 60065 may have spotted the
potential for some problems because the legacy standards classify energy sources and
circuits differently. One example is that a 60950-1 certified switched-mode power supply
typically has output circuits classified as safety extra-low voltage (SELV), whereas IEC
62368-1 refers to ES1 energy sources, which considers both voltage and current. As a
result, SELV is no longer defined.
Although this is true, TC108 has taken a pragmatic approach to the issue, and has
recognized that a SELV circuit is intended to be safe to touch by a user or operator, in the
same way that an ES1 source is safe to touch by an ordinary person
The logic underlying HBSE can be summarized as follows:
●
Identify the energy sources used
●
Measure the energy levels they produce
●
Determine whether the energy from the sources is hazardous
●
Classify it accordingly
●
Identify how energy can be transferred to a body part
●
Determine appropriate safeguard schemes:
○
To protect defined persons against pain and injury from the classified energy
sources, as well as
○
To reduce the likelihood of injury or property damage due to an electrically caused
fire originating within the equipment
●
Measure the effectiveness of those safeguards
In addition to considering bodily injury, 62368-1 also applies the HBSE three-block model to
analyze the potential for electrically caused fire resulting in damage to persons or property.
Moreover, 62368-1 references all energy sources applicable to ICT/AV electrical equipment.
These encompass electrical energy, thermal energy such as hot accessible parts, chemical
energy encompassing electrolytic reactions or poisons, kinetic energy such as moving
parts, and radiated energy including optical or acoustic energy.
No employed safeguard could be an option against class 1 energy sources, and the level of
energy remains below specified class 1 limits under normal operating conditions, abnormal
conditions, or in the presence of a single fault.
As far as class 2 energy sources are concerned, energy levels exceed class 1 limits but
remain below class 2 limits during normal, abnormal or single-fault conditions. The energy
present may be sufficient to cause pain but is not likely to cause injury. For fire analysis, the
energy could be enough to cause ignition under some conditions. At least one safeguard is
required to protect ordinary users from class 2 energy sources.
Class 3 energy sources are the most hazardous. The energy exceeds the class 2 maximum
limit under normal, abnormal or single-fault conditions. Class 3 sources can cause injury,
or ignition and spread of fire. The type of injury caused by a class 3 energy source may
be fibrillation, cardiac/respiratory arrest, or skin and/or internal organ burn. A double or
reinforced safeguard is required to protect an ordinary person from class 3 energy sources
The actual current and voltage limits applicable to ES1, ES2 and ES3 vary. For example,
the voltage limit requirements are influenced by frequency. For voltages below 1 kHz,
the ES1 limit is 30 Vrms, 42.4 Vp, and 60 Vdc. The ES2 limit is 50 Vrms, 70.7 Vp, and 120
Vdc.
The term “ordinary person” in 62368-1 is equivalent to “user/operator,” and “skilled person”
is equivalent to “service person.” 62368-1 also defines the category “instructed person,”
which applies to those who have been instructed and trained – or are to be supervised – by
a skilled person.
Tomi Engdahl says:
Inside a mains socket tester with LCD display. (with schematic)
https://www.youtube.com/watch?v=-xm4l13aY6I
polarity test is an important part of the test of an electrical installation. This plug is simple, but very functional. It’s not as glamorous or sophisticated as the “Socket & See” tester with its automatic loop impedance check (the resistance of the entire live/earth loop to the utility transformer) but it’s a fraction of the price.
Tomi Engdahl says:
Good versus evil socket testers. (with schematics)
https://www.youtube.com/watch?v=3_3FCAbNyMM
One of these socket testers is great and one has been over-engineered with lots of extra weaknesses as a result. In hindsight I’m wondering if the hot resistors (110C) were masking the transistor or if the transistor itself was getting that hot. If it is dissipating about quarter of a watt then it should be within its capability.
Tomi Engdahl says:
Why Fluke are recalling their SM100/200/300 plug-in testers.
https://www.youtube.com/watch?v=_KOYt-0WZxg
Fluke are recalling their plug-in socket testers and offering exchange products. There’s nothing actually wrong with the testers other than the modest current used to power the test indicators that can cause a strong sensation when a ground path is open circuit and someone bridges it during the test. (mild shock risk)
The recall is more an indication of the increasingly litigious nature of society and the current trend of deskilling the electrical industry with useless 1-week certification courses motivated entirely by profit.
Tomi Engdahl says:
http://www.etn.fi/index.php/13-news/8786-sahkoturvallisuudessa-oli-isoja-puutteita-vuonna-2017
Tomi Engdahl says:
Led-valoja on aika lailla kaikkialla – nyt tutkijat havaitsivat niissä vaarallisen ominaisuuden
https://www.kauppalehti.fi/uutiset/led-valoja-on-aika-lailla-kaikkialla-nyt-tutkijat-havaitsivat-niissa-vaarallisen-ominaisuuden/5fe40e60-53d0-4f9c-807b-0055c21088e3
Moni rakennuspalo olisi estettävissä valaistuksen ennakoivalla kunnossapidolla.
Valaistus aiheuttaa merkittävän määrän rakennuspaloja, mutta se tunnistetaan vain harvoin paloriskiksi. Useimmin syynä ovat vanhat loisteputkivalaisimet, mutta markkinoita valtaavat leditkään eivät automaattisesti ole paloturvallisia.
led-valaistus on paljon perinteisiä valaistusratkaisuja turvallisempi, mutta ledeissäkin on vielä puutteita
led-valot aiheuttavat suuren sytytysvirtapiikin, joka lyhentää myös muiden verkkoon kytkettyjen laitteiden elinikää ja aiheuttaa siten kasvaneen paloriskin.
Tyypillisesti vanha loisteputki korvataan led-putkella, mikä on helppo, mutta tutkimuksen perusteella riskialtis ratkaisu.
Myös tuotevastuun kannalta ledien tee-se-itse -muutokset voivat olla ongelmallisia
Tomi Engdahl says:
Russischer Elektriker macht einen fatalen Fehler!
https://www.youtube.com/watch?v=dIjXTfRa_2s
Tomi Engdahl says:
Zones for Concealed Cables in Walls, BS7671 Wiring Regulations
https://www.youtube.com/watch?v=c4BsettT0N8
Zones for concealed cables in walls as defined in BS7671. Safe zones in the 17th edition and earlier, prescribed zones in the 18th edition.
Comments:
Its just a shame that 95% of home owners are oblivious to such things as safe zones – hence the continuous need for cable repairs where nails, screws and drill bits have done a bit of damage.
With all those “safe spaces” for electrics, British walls are no longer anchored properly to house frames. Due to the crumbling walls, UK homes will no longer be considered to be safe spaces.
It’ is interesting to see the differences between UK and North American wiring standards. In NA most houses are wood frame, with wiring running through holes in the wooden studs. I don’t believe we are allowed to embed unprotected wiring at a depth of less than 2″ anywhere.
Tomi Engdahl says:
Grandma’s house – construction fails, electrical oddities and 7 CATS!
https://www.youtube.com/watch?v=mxWgwlnde_w
Visiting grandma in her old house and documenting its dodgy wiring, construction fails and of course, grandma’s seven cats :).
Tomi Engdahl says:
Electric heated “suicide” shower PART 1 – teardown & calculations
https://www.youtube.com/watch?v=jo99U3nVCnA
Electric heated “suicide” shower PART 2 – test & measurements
https://www.youtube.com/watch?v=jiErqUkw690
Tomi Engdahl says:
From https://www.youtube.com/watch?v=XUtj-bWHeKY discussion:
A lot of the things I plug into the wall don’t have a fuse. Lamps, power tools, Christmas lights, aquarium filter and bubbler. But then again I only plug it in to the voltage it was designed for
Actually a lot of these things have fuses built in that are just less obvious. Power tools usually have a thermal fuse in the motor, incandescent bulbs have a small, thin wire below the filament that acts as a fuse for when the filament fails, and then lots of things have PCB mounted fuses of course, some of which may not look like a fuse.
Christmas lights in the USA typically have fuses in the plug
circuit breakers are typically rated to “instantly” break, (<100ms) in the case of type B at 3 – 5x the rated current. This is to account for loads being switched on that have high inrush current – motors, power supplies with capacitors, lamps, this kind of thing. so a 32A breaker could deliver up to 160A for a few seconds or even minutes depending on the overload, rather than tripping instantly. It is relying on the bi-metallic strip heating up to trip the circuit, rather than the electromagnet.
So the Weller must of really been melted, for you to be so shocked about no fuse, even some thermal fuse… No?
UL and CE should require over-current and over-voltage protection, and fire and electric shock fail-safe up to reasonable, destructive-tested values.
Normal fuse protect only against over current and not over voltage
That isn't correct. The iron-core mains transformer designed for 120V will saturate at 240V and thus the current will increase very much (not just 2x) and it will blow the fuse immediately, before any heating issues occur.
Of course with an "ideal transformer" things would be different, you would just get 2 times the output voltage and 4 times the output power towards the iron, and a fuse would not blow that easily.
Tomi Engdahl says:
Hot Plug Indicator new From Safe Connect the Makers of the Hot Connection Indicator (Prototype)
https://www.youtube.com/watch?v=ajOA-zSE_8U
This is the prototype of the Hot Plug Indicator a new product from Safe Connect the makers of the award winning Hot Connection Indicator. In this video under controlled conditions we overload a 13 amp BS 1363 plug top. This overload causes the plug top to heat up and turn the sticker from pink to red. This product gives a visual warning that a plug top has got hot by turning the sticker red at 52 degrees and above.
Tomi Engdahl says:
Electrical Safety Testing
Reference Guide
https://www.psma.com/ul_files/forums/safety/estguide2.pdf
Tomi Engdahl says:
Dubious C5 Power Lead
https://www.youtube.com/watch?v=Ib7Dd92mGRQ
The ‘BS1363′ plug has a sleeved earth pin. The fuse is obviously of poor quality, possibly fake. Conductor resistance is 2x-3x what it should be. The C5 end contains steel/ferrous components.
Tomi Engdahl says:
Dangerous Euro Extension Lead from Greece
https://www.youtube.com/watch?v=5ajdXuzDD0s
A dangerous and poor quality extension lead purchased in Greece with Russian packaging. Everything about this device is a fail.
Tomi Engdahl says:
Single Wires through Metal Holes
https://www.youtube.com/watch?v=hg5eZkq2KgE
When installing a metal consumer unit, the line and neutral wires should pass through a single hole. If they are passed through separate holes, the resulting magnetic field can create eddy currents in the metal, causing overheating.
In this video, a current of 25A and 120A is passed through a single wire which is routed through two holes in a metal consumer unit to see if it overheats.
Comments:
Well this guy appears as professional as you can get… but deep down each and every single guy… unless shit blows up or goes on fire, it pretty much means it was a disappointing test!
A very worthwhile test. I’ve always been a bit sceptical about the ability of a single core being able to induce a significant current in the surrounding metalwork. This appears to be a myth that goes back a long way, and I wonder if it is an issue with more industrial supplies (I’m not so sure) or if it was a myth born from an excuse for overloaded cables. It also suggests that the people who write the regulations haven’t actually tested it.
How about a single wire through a metal conduit. Aus standards prohibit doing so, requiring the full current to return via the same run through the metal, be it a switched live, other phases or neutral wire.
Interesting, I was expecting a larger increase, given the dire warnings that used to be given. I wonder if in a real world situation, if the high frequency harmonics produced by large amounts of switching power supplies these days may cause this to be a much more significant problem in commercial installations (thinking of 400-1600 amp commercial supplies with IT equipment hooked up). I know these harmonics can cause problems with neutral overheating on 3ph supplies, maybe the extra eddy current loss at higher frequencies would cause issues too?
Came across a 3 phase meter in a factory unit connected with 25mm tails which came through individual holes in a metal trunking under the meter. The trunking was running very warm!
An enjoyable and well exicuted video, but i cannot stress highly enough the very real problems that eddy currents cause in poorly designed switchboard and cable ladder installations. Eddy current heating typically is only an issue in installations running over 250Amps @ 50 Hz, so whilst your video addresses the (watch makers currents found in domestic consumer units), try the same test with the same consumer unit fitted inside an insulated wall cavity with third order harmonics and a few well loaded RCBO’s all adding to the heat rise.
i was involved once with a television transmitter installation where they ran 3phase power to the main disconnect box using three separate conduits, one phase in each conduit . Those got red hot! Granted it was a hundred amps and the metal separating the conductors was not just the metal box, but was a length of about 10 feet of conduit; but that situation was an example of the same effect. The conduit / metal box created the core of a transformer.
The solution was to run three separate smaller size wires in each of the three conduits so that each conduit contained all three phases adding up to the required wire size for the current draw.l
Good video debunking that myth. As for me I new that the heating effect would be negligible otherwise arc welders which invariably have separate single wire connectors through metal cases would go up in flames or could double as electric cookers.
No. A welder should not output AC. It was only used historically when they didn’t have solid-state rectifiers. The welds were inferior.
Tomi Engdahl says:
Illegal and Deadly imported UK Plug Rant
https://www.youtube.com/watch?v=1RklIu4SE3M
No animals were hurt during the filming of this video
– The 15.2V was the actual voltage at the output terminals of the power supply, which is a totally safe voltage to be playing around with. There was no risk whatsoever of electrocution when I did this – the only real risks were from the molten plastic (which could have stuck to their fur), or from the plastic fumes as it burned off (which is why I filmed this outdoors in the first place). Hope you’re having a good weekend. Cheers!!
I’m surprised that was the actual voltage. That would mean the cable had a resistance of about 3 ohms, which seems a bit high unless it’s got quite thin wires.
you got 5 amps at 15 volts dc through it, thats 75 watts, Now do the same test at 240 volts ac……. (You wil trip a 20 amp breaker before the wire even gets warm)
the test is not demonstrating what happens when a dead short occurs… its simulating a high load over time… its not the voltage that makes the wire get warm its the current… the current going threw the wire was well within the “rating” of 10 amps…. so if u plugged a gaming computer into this wire… 15 minites into playing your game.. the carpet behind your desk would have melted plastic on it and very possibly a bare 240V live wire… at least for this type of plug
Good demonstration! With a total resistance of about 3 ohms for that short cable the manufacturer obviously wasn’t wasting money on much copper. Worth pointing out that the UK system allows for fusing at just 1A which, with the right plug & fuse would make even thin rubbish cable like that reasonably safe. Not something one can say for the Schuko or US style systems.
Cool video and such dodgy leads are still on sale in 2018.
All genuine U.K. plugs are rated at 13amps and one needs to read the data from the cable sheath to calculate it’s current rating e.g. 0.75mm flex is typically 6amps assuming it is really copper and the makers are not lying.
Fake U.K. plug fuses also exist which cannot clear high fault currents and may not even have the correct size wire so beware of these also.
Tomi Engdahl says:
Overheated Plug and Damaged Socket Outlet
https://www.youtube.com/watch?v=b99n3tesnqY
What happens when a plug with a loose connection is used in a socket outlet.
The plug in this example was from an extension lead and was probably used in a damp location, causing the green corrosion on the earth pin.
Tomi Engdahl says:
Multimeters for electrical installations
https://www.youtube.com/watch?v=rrqa-R1zCWQ
Basics of multimeters, what they do and how to use them. This is from an electrical point of view – for electronics the features required will be different.
Includes the basics of voltage, current and resistance, how to measure those three things, manual and auto ranges, CAT ratings, a look inside two multimeters.
Comments:
remember working on a site back in the 1990′s when a fellow electrician made the very mistake of leaving his multimeter set to current (amps) before placing the test probes across 400 amp busbars in an LV switch panel…..nasty business…..ambulance called for 2nd degree burns and skin grafts as I remember. Take care with electricity guys….it can bite you bad.
That’s why I’m fan of using mainly meters with no current ranges (or clamp meters, they usually measure current only via clamp) in such environments and having one meter with current buried deep in drawer/tool bag when you actually have to do current measurement by wire.
Interesting article. One thing I will say, multimeters fall under the remit of IEC61010. One of the sub sections for that is for requirements for multimeters and it explicitly stated that meters must be rated CATIII as a minimum
Tomi Engdahl says:
Electrical Measurement Categories – CAT I II III IV
https://www.youtube.com/watch?v=LTGs6GXB8io
Measurement categories for electrical measurement equipment such as multimeters.
CAT I equipment is not suitable for connection to the mains supply, CAT II and above is, but the distance from the energy source is important, with CAT IV being nearest to the energy source such as where power enters a building.
Tomi Engdahl says:
Wiring Color Codes
https://www.allaboutcircuits.com/textbook/reference/chpt-2/wiring-color-codes/
Wiring for AC and DC power distribution branch circuits are color coded for identification of individual wires. In some jurisdictions all wire colors are specified in legal documents. In other jurisdictions, only a few conductor colors are so codified.
IEC, AC: Most of Europe abides by IEC (International Electrotechnical Commission) wiring color codes for AC branch circuits.
US, AC:The US National Electrical Code only mandates white (or grey) for the neutral power conductor and bare copper, green, or green with yellow stripe for the protective ground. In principle any other colors except these may be used for the power conductors. The colors adopted as local practice
Canada: Canadian wiring is governed by the CEC (Canadian Electric Code).
IEC, DC: DC power installations, for example, solar power and computer data centers, use color coding which follows the AC standards.
US DC power: The US National Electrical Code (for both AC and DC) mandates that the grounded neutral conductor of a power system be white or grey.
Tomi Engdahl says:
Dangerous Euro Extension Lead from Greece
https://www.youtube.com/watch?v=5ajdXuzDD0s
A dangerous and poor quality extension lead purchased in Greece with Russian packaging. Everything about this device is a fail.
Comments:
As a Greek, I advise people to buy extensions and electric cables either from stores that sell home electric appliances or from specialised stores that sell electric items and are run by professional electricians.
As a greek my defense is: we are too lazy to make this kind of cheap crap.
My other thought is that the Europlug when inserted into a wall socket without a ground is reversible? So that means the live will not be switched off by the switch, that combined with the lack of shutters..
Also the L/N contacts in the socket look like they bend and connect to the earth rail?
yeah all european plugs and sockets are reversable. both earthed and unearthed sockets. (unearthed sockets are no longer fitted but they are still common in older instalations.)
Ahh, but of course!
Was referring to the extending Earth pin in the French CEE 7/5 to polarise it, but I now find there is no standard for wiring it so makes no difference aha
In France they connect live on the right hole,In Poland they connect live on the left hole.Still not polarized despite the same plug and socket.
the original plugs were designed in the 30′s even i think although the standard as it is today probably mid 70′s and 80′s
If you have a small europlug, for double insulated devices that only has line and neutral connections (no earth) those can be reversed anyway in both systems.
Appliances in the EU are tested to conform to standards rendering the difference between “live” and “neutral” redundant.
Notice that in some places there are 230V 2-phase instead. This exists in some areas in Norway based on that it’s hard to get a reliable ground – granite is a bad conductor.
Many appliances also have switches cutting both leads and not only one of them.
Might be from Greece but it’s a cheap Chinese fake job, euro extension leads, dutch ones with the earth pin in the sockets are rated 16A 3.8kw and the lead is 3x 1.5mm2.
Tomi Engdahl says:
The Dangers of UK Safety Socket Covers
https://www.youtube.com/watch?v=d-WhFgaqCX0
Demonstrates how socket covers for UK power sockets are actually dangerous, not just useless.
Tomi Engdahl says:
What Happens If You Use Multiple Coiled Extension Cords?
https://www.youtube.com/watch?v=MGqNKEIQGWQ
What happens if you use multiple extension cords? Or if don’t unwind them before use? Will there be any reactive current? Is it safe to use them like that? We try to find out
Don’t try this at home or try to recreate our experiments at home!
Tomi Engdahl says:
Extension Cord Safety Virtual Demonstration
https://www.youtube.com/watch?v=VmWlka-SG1o
Extension cords offer a convenient solution for delivering power right where it’s needed. But proper selection and use of extension cords is critical to avoiding injuries. An estimated 3,300 residential fires originate in extension cords each year, killing and injuring more than 300 people. In addition, nearly 4,000 people are treated in hospital emergency rooms each year for non-fire related extension cord injuries, including fractures, lacerations, and electrical burns.
Prevent potentially dangerous extension cord mistakes by following a few simple guidelines.
Tomi Engdahl says:
Are RV dog bones (30 to 15 amp adapters) safe?
https://www.youtube.com/watch?v=sHPXqP6fC4E
I noticed my extension cord was pretty warm and had to check how much power I was using. Good thing I caught it in time.
HOW NOT TO HOOK SHORE POWER FIRE FAIL
https://www.youtube.com/watch?v=L23d4Eq5pX4
I connected my 50 amp shore power line to a 30 amp dog bone to a 15 amp plug and plugged it into a household extension cord. The extension cord was left coiled up. I thought the motorhome was drawing about 6.5 amps, but obviously it kicked way up and set the extension cord on fire
Tomi Engdahl says:
You’re using your Extension Cord Reel wrong!
https://www.youtube.com/watch?v=-gmp46HBRhg
Extension cord reels, or rolly cords as I like to call them, are seriously handy. Nobody likes spending 30 minutes untangling a 50m extension cord.
Trouble is, usually we use them incorrectly.
It turns out you have to read the fine print: You can only use the full capacity of the reel if you fully unwind the rolly cord.
If you don’t fully unwind the cord, the power rating of the reel drops by a factor of 3, which means the current you can draw drops by a factor of 3, which means you’re likely to destroy the poor thing!
Rolly cords have (usually) thermal circuit breakers, but those breakers are a) cheap, and b) designed to trip at the max current for the reel when the cord is fully unwound.
Technically, this is “overheat protection”, but in my experience it doesn’t work well at all when the cord is still on the reel – even with premium brand reels.
Tomi Engdahl says:
Trust me, I’m an Electrical Engineer! Funny Electrician Fails
https://www.youtube.com/watch?v=3j_ArICWGDU
Not the brightest sparks! Ladders balancing in pool, wonky wall sockets and fans blocked by light fixtures – the worst electrician fails seen on social media. Trust me, I’m an Electrical Engineer!
Tomi Engdahl says:
Electrical Installation Testing
https://www.youtube.com/watch?v=Sc0tJGl4Oas
Introduction to the series on testing, this covers the different tests and the order they are done in.
Tomi Engdahl says:
Shock Hazards Associated with Electric Guitars and Amps
https://www.youtube.com/watch?v=xS_5K5YEYv8
This is a discussion of the shock hazards associated with electric guitars and amplifiers, created in response to comments and questions received after I posted the Death Capacitor video. In it, I explain the source and nature of the shock hazards and how to avoid and eliminate them. I hope this information is both interesting and informative, and helps to spare you from a painful shock….or worse.
Tomi Engdahl says:
The Death Capacitor……Fact or Fiction ????
https://www.youtube.com/watch?v=MMTN3B-zClo
This video is an investigation into the infamous “Death Capacitor” which is present in most vintage amplifiers. Much has been said about the shock risk they pose and the necessity to remove them from all amplifier circuits, but is it really true? Using three vintage amps, I will demonstrate the location, purpose, functionality, and actual hazard (if any) associated with these seemingly innocuous components.
What does change, however, is which component the incoming AC encounters first: the capacitor or the primary winding of the power transformer. Since the purpose of the capacitor is to act as a filter to eliminate “noise” within the incoming AC, the AC must first encounter the capacitor, where “noise” can be eliminated, and then the primary winding. The purpose of the Fender “Grounding Switch” is to allow you to reverse the polarity of the AC primary input so the “hot” wire encounters the cap first, to reduce noise…..or, lacking the switch, you can simply reverse the plug in the outlet to accomplish this.
Tomi Engdahl says:
The Power Grid, Isolation Transformers and Earthing
https://www.youtube.com/watch?v=OBYzvkY2-eA
In order to explain the idea behind some isolation transformer units I’m working on at the moment, I explore the power grid, safety features of electric installations, Earthings Systems and RCDs.
Types of Earthing System for Electricity Supplies (UK)
https://www.youtube.com/watch?v=AWxeb2MI37c
The three main types of earthing for mains electricity supplies to buildings in the UK. TT, TN-S and TN-C-S.
Tomi Engdahl says:
TSP #85 – Teardown & Repair of a Sencore PR570 Variable Isolation Transformer & Safety Analyzer
https://www.youtube.com/watch?v=KzOXdpxzIZM
In this short episode Shahriar performs a teardown and repair of a Sencore PR570 variable isolation transformer and safety analyzer. One of the LCD segments of the unit does does not display.
Tomi Engdahl says:
Every maker should have…[Pt.28] an Isolation-Transformer and a Variac
https://www.youtube.com/watch?v=FuEmGR8bBEc
Roger explains why you should have an isolation-transformer for your personal safety.
How does it work, what can you do with it and what is the difference to a Variac.
It´s cheaper and quite easy to build one of your own.
Tomi Engdahl says:
Deadly isolation transformer flogged on ebay
https://www.youtube.com/watch?v=hFTVYwvn114
They sell anything on Ebay. Buyer beware, don’t get burned like this person did.
Tomi Engdahl says:
Isolating transformer, portable, testing
https://www.youtube.com/watch?v=YdZy41gGUY4
Portable Isolating transformer testing. Caution the standards for testing change from time to time. Check for validity in your area. The principles of testing are the same all over the world. The wires that are supposed to be joined together should have continuity (low resistance). The wires that are not supposed to be joined together have insulation (very high resistance) in excess of 1 million Ohms- 1M Ohm. There is no requirement to open an appliance for testing.
Radio Repair Shop Isolation Transformer Safety Test
https://www.youtube.com/watch?v=BVYsb-LaMDQ
I recently installed an isolation transformer and I perform a quick check to positively prove that it is fully isolated from the power lines. I need to know for sure so I can better maintain my safety.
Tomi Engdahl says:
$3 multimeter – high voltage & overcurrent test (smoke and explosion)
https://www.youtube.com/watch?v=iGUiZT6kLDk
high voltage test and overcurrent test of the 3 USD multimeter
$3 multimeter test & teardown
https://www.youtube.com/watch?v=R693vS09hoo
Tomi Engdahl says:
Dangerous Chinese Power Extension (+ wire maths & circuit breakers explained)
https://www.youtube.com/watch?v=_kEd1bVSyME
So I managed to make a 22 minute video about a piece of wire :). Actually, I made a thorough analysis of a cheap and dangerous power extension from China for LED strings or anything else. I explain some calculations of a voltage drop on its resistance and the power dissipation. I also talk about calculating the conductivity (inverse of resistivity) of a wire. The tripping curves of circuit breakers are also explained. And of course, the video contains some stupid and dangerous experiments with a short circuit and lots of smoke :).
Tomi Engdahl says:
Electrical Shock Hazards & Its Effects on Human Body
https://www.electricaltechnology.org/2018/08/electrical-shock-hazards-its-effects-on-human-body.html
When working with or nearby electrical installations an electrical shock, arc flash or arc blast can occur and a current can go through the body, due to the following situations:
Direct contact with live parts of the installation (exposure to live parts)
Contact with parts that normally are not live, but as a consequence of a fault become live accidentally (indirect contact)
Existence of potential difference between different points in the ground
Tomi Engdahl says:
https://en.m.wikipedia.org/wiki/Electrical_safety_standards
Tomi Engdahl says:
Main Cause of Electrical Fires – First Stop Safety training video
https://www.youtube.com/watch?v=Hq8wN-pUaqw
The Formal Visual Inspection is an important part of maintaining a safe working environment.
This drives the message home by outlining the main causes of electrical fires.
• Fuse in plug replaced by nail
• Too high a fuse in plug
• Loose terminal screws in a plug
• Overloading of extensions
• Not unwinding coiled extension leads
• Blocking ventilation slots
• Combustible substances close to electrical appliances
• Appliances left on overnight
It is important to have a good understanding of Amps and Kilowatts when it comes to preventing fires.
Tomi Engdahl says:
Electronics & Water? What could possibly go wrong?
https://www.youtube.com/watch?v=pGLUsQozT94
In this video I will show you how water and electricity/electronic circuits correlate by conducting a couple of experiments. Along the way we will bust a couple of preconceptions and find out whether we can use electronics underwater.
Tomi Engdahl says:
The Outlet that Saves Lives
https://www.youtube.com/watch?v=GlM6PE2kKVY
Ground Fault Circuit Interrupter or GFCI outlet is the hero in the washrooms! Make sure you have it installed, and you plug your electronics in GFCI.
Comments:
Love this guy’s videos. Hilarious and educational at the same time. Plus the way he tests things on himself and has ridiculous reactions.
You are a comedic genius, intentional or otherwise.
He understands GFCI’s better than 80% of professional electricians in my state.
U.S. Electrician here. I have worked with both RCCB’s in Europe and GFCI’s.
One weakness GFCI’s have is the mechanism will NOT operate under a short circuit condition.
For those that do not know, GFCI’s monitor the current between the hot and neutral. In theory, under normal operation, the current on the phase will match the current on the neutral. If there is a difference, 3-5 milliamps for GFCI’s, between the two, the GFCI mechanism will sense that imbalance and trip, since the design assumes the imbalanced current is then going to ground. Hence “Ground Fault”.
However, under a short circuit condition from phase to neutral, in spite of the high amperage, the current will remain the same from phase to neutral, thus not triggering the GFCI function.
I have tried this myself at home. I have taken two wires, inserted them into the hot and neutral slots of a GFCI outlet, then touched them together. Sure enough, the circuit breaker (A new one I replaced) tripped under an overcurrent condition, but the GFCI on the outlet never functioned.
Still, around water, GFCI’s have saved lives, since most equipment have means to provide a path to ground.
Tomi Engdahl says:
Worst Electrical Work Ever
https://www.youtube.com/watch?v=GGeOjASps7w
Some pictures of some of the worst electrical work you will ever see!
Tomi Engdahl says:
The truth about Electrical fires
https://www.youtube.com/watch?v=_2HyTRxzwXs
Retranscription
Interview with Cyril Charles,
electrical fire prevention specialist
http://www.incendies-origine-electrique-electrical-fires.com/interview_with_cyril_charles_by_annie_lobe_electri.html
Tomi Engdahl says:
Keeping yourself and others safe when designing and making electronic projects
Electrical safety when creating DIY electronic projects
http://www.penguintutor.com/electronics/electrical-safety
Mains voltage electricity is extremely dangerous. There is a significant risk of death through electrocution if mains voltage electricity is allowed to pass through the body. There can also be a risk of fire and explosion if electricity is not cabled and fused correctly. Therefore precautions must be taken when using mains electricity or similar.
There is a lot that can go wrong with electricity with potentially dire consequences. Some of these are obvious
Read this page in full and ensure you think about all the aspects when designing your next circuit. If in any doubt seek out the advise of a qualified person.
Tomi Engdahl says:
Dangerous Extension Lead in Use – 6 Amps Melting
https://www.youtube.com/watch?v=WCS_CTBxu5U
The dangerous extension lead is connected to a moderate load. Even with only 6 amps the temperature rises and in 4 minutes has reached 300C and completely destroyed the cable.
The plastic casing is flammable and continues to burn until it’s all consumed by the fire.
Comment:
Europe is under attack from the Chinese, and we pay them to do it!!.
Seriously, very scary for the homeowner who assumes that it is safe to use.
Excellent test setup, thanks for sharing.
This extension lead is extremely dangerous and we must deal with it! starts hydraulic press
These garbage mains accessories are even worse here in the US, where we’re too much of pussies for real voltage…
Tomi Engdahl says:
Dangerous Multiway Extension Lead ASTRA BT311 (Part 1)
https://www.youtube.com/watch?v=e0ghsODkqUQ
A very poor quality multiway extension socket with flex and illegal plug attached.
Virtually everything about this device is wrong and dangerous.
The plug has no fuse, making it unsafe for use in the UK – most UK outlets are connected to 32A circuits and all UK BS1363 plugs contain fuses.
Even when used with a 10A fused circuit it would still be dangerous, there really is no possible way to use this thing safely.
Dangerous Multiway Extension Lead ASTRA BT311 (Part 2)
https://www.youtube.com/watch?v=C1h9LLJJvk0
A very poor quality multiway extension socket with flex and illegal plug attached.
This is part 2, in which the unconnected earth wire is investigated, the unfused plug is dismantled and the various claims printed on the product packaging are examined for credibility.
Tomi Engdahl says:
A Fire Department Warned People To Never Make This Dangerous Mistake With An Extension Cord
https://www.youtube.com/watch?v=W9U9ZXQWdXw
According to the National Fire Protection Association (NFPA), there were in excess of 365,000 house fires in the U.S. in 2015. And perhaps even more alarmingly, many of those blazes can be chalked up to either accidents or to things found in the home. It’s arguably no wonder, then, that an Oregon fire department has seen fit to caution the public about using one common household item: the humble extension cord. And the warning the department gave out was grim indeed.
And as it turns out, extension cords can start fires as well.