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Buying mains products online? Maybe from markets or “$2 shops”? Beware: a lot of what you’re buying could be a death trap! The Electrical House of Horrors by Dr David Maddison W e take for granted the safety of mains-operated appliances. With few exceptions, anything purchased in Australia from a legitimate retailer can be expected to conform to the appropriate safety standards and therefore be safe to use. Of course, there are still ways to get electrocuted, for example, taking a bath with a toaster or a hairdryer close by is a terrible idea. But you already knew that! The real danger is that you might purchase an appliance which appears to be properly designed and made, and may even appear to have the appropriate approvals and certifications, but it could still be very unsafe. In the worst case, mains voltages may appear where they shouldn’t – in exposed metal that you (or someone else) can easily come in contact with. 14 Silicon Chip Some of these unsafe products may even have a reputable brand printed on them; ie, they are counterfeits. Unfortunately, many overseas countries which are the source of low-cost electronics online have much weaker electrical standards than ours (or none at all!). And they may also have very lax enforcement of counterfeiting or faking of regulatory markings. Many of these dodgy devices find their way to Australia. In this article, we’ll take a look at many device ‘teardowns’ (ie, disassembly) and other investigations of unsafe electrical goods. Many of these have been done by Australians, but some are by people in other countries with similar electrical standards to our own. Many of these teardowns are posted as YouTube videos, so if you want to know more, follow the shortlinks shown. Australia’s electronics magazine siliconchip.com.au    It doesn’t even need to be mains operated to be a real danger. The internet is full of horror stories about rechargeable cells – like this Li-Ion 18650, which is literally exploding. This could be due to poor manufacturing standards or    poor handling (eg, overcharging/discharging, etc). Phone chargers There are numerous cheap (and nasty!) phone chargers on the market and many, if not most, are dangerous. Many people, including at least one Australian, have been electrocuted due to the use of such chargers. You definitely should only use chargers from the original phone manufacturer or reputable after-market manufacturers. Of course, you should not use a mains-powered charger (or any mains-operated devices) in wet areas such as in a bathroom or around a swimming pool or spa. A good exposé of some fake phone chargers is in a video from Australian blogger David L Jones titled “EEVblog #388 - Fake Apple USB Charger Teardown” at: siliconchip. com.au/link/aau7 (see Fig.1). This ‘teardown’ looks at some fake Apple chargers which lack the safety and genuine UL certification of real Apple chargers. He found problems including: • easy-to-remove internals without tools • no full-wave rectifier • very low clearance between mains and low voltage components (‘creepage’ distance) • no isolation slots on circuit board between mains and low voltage • no fuse protection such as fusible resistors or resettable devices • no inductive filters • no insulating layer between primary and secondary circuit boards on one of the devices investigated • small creepage distance between transformer primary and metal shield of USB connector • no snubbers (an energy absorbing circuit element) • no filter capacitor between primary and secondary of the switching transformer on one device • standard capacitor in place of Class-Y safety capacitor between primary and secondary of transformer on one device • no controller IC (not a danger but an indication of a primitive design) • no Mosfet but cheaper transistors in one device The transformer in these devices was not examined, but one can assume that they are unsafe, as has been found in many other similar devices. There were no Class-X or Class-Y capacitors in the counterfeit chargers. These are safety-rated capacitors designed for line voltage use. Class-X capacitors are generally used to suppress symmetrical interference and go across the line, from Active to Neutral. Class-Y devices are used between Active and Earth or Neutral and Earth, to suppress asymmetric interference. A failure in a Class-X device due to overvoltage may result in short circuit, leading to the tripping of a circuit breaker. Class-Y capacitors are designed to fail open-circuit, because if they short circuit, the Earth conductor could become live which would be a real hazard. The following link contains a teardown of a genuine, safe Apple charger. You can see that there is quite a difference from the cheap fakes David pulled apart: www.righto. com/2012/05/apple-iphone-charger-teardown-quality.html Another good video on this subject is titled “DANGEROUS Chinese USB charger (no isolation in the transformer!)”, and you can view it at: siliconchip.com.au/link/aau8 (see Fig.2). Fig.2: in this phone charger tear down by DiodeGoneWild, the only insulation that existed between the primary mains windings and the secondary windings was that provided by the enamel insulation of the wires. YouTuber DiodeGoneWild points out several safety violations. The worst of these is probably that the only insulation between the primary and secondary of the mains transformer was the enamel on the wires. There was no insulating tape layer, as is required for mains transformers. This omission makes it extremely dangerous. General-purpose USB chargers Here we look at some dangerous general-purpose USB chargers, not specifically designed for phones although they can be used as such. See the video titled “Dangerous Chinese Travel Extension with USB Charger – teardown” at: siliconchip.com. au/link/aau9 In it, YouTuber DiodeGoneWild investigates a device for travellers that is available online (Fig.3). It combines an extension cord with a multi-country (including Australia) Counterfeit electrical products Fig.1: underside of fake “Apple” chargers during examination by David L Jones. Numerous safety violations were discovered. siliconchip.com.au Counterfeiting of Australian electrical hardware (and other products) is a serious problem, and the counterfeit products are generally substandard, and possibly dangerous. One Australian manufacturer of electrical hardware makes a relevant statement on their webpage, at: siliconchip.com.au/link/aaua Australia’s electronics magazine December 2019  15 Fig.3: YouTuber DiodeGoneWild investigating a dodgy combined USB charger/mains power extension cable with numerous safety problems. Fig.4: bigclivedotcom looking at a transformer with failed insulation due to poor quality control. This fault could have lead to electrocution. grounded outlet and four USB charging sockets. Even though it has a grounded outlet, the device’s plug only has two pins. It also has a cartoon character on it, making it attractive for children to play with. The investigation revealed the following problems: and many of these are quite acceptable for beginner use. A general warning: only those produced by a reputable manufacturer should be used to measure mains or high voltages. Some are not safe at the voltages that they claim to be able to handle. Some also falsely claim to have a fused input. There can also be significant safety and quality variations between samples of the same model; they can have completely different internals despite a similar or identical external appearance. One reason for this is that some might be genuine products, and others might be fakes. See the video titled “Tiny $2 Multimeter with 1000V Range! Test with Smoke” at: siliconchip.com.au/link/aauc by YouTuber DiodeGoneWild. This shows the internals of a US$2.20 analog multimeter (Fig.5). It was rated at 1000V and yet had no fuse, close PCB track spacings, the probes came out easily and it used tiny surface-mount resistors. It’s only safe for use at low voltages. Another video by the same author titled “$3 multimeter test & teardown” can be seen at: siliconchip.com.au/link/ aaud This is another cheap digital multimeter, commonly available on eBay, which cost US$3, including delivery to Europe. Safety violations discovered included: • certain plugs could be inserted with one pin in the device and another outside, thus leaving a live exposed pin • a very thin mains cable that could not safely carry the current claimed • the case was easy to disassemble without tools, including by a child, exposing live components • the USB power supply had areas of inadequate separation between tracks and also had regular capacitors in place of Class-Y safety capacitors • the USB output failed after 3A current draw for 30 minutes (it was rated at 4.8A) • children’s fingers could fit into the mains power outlet sockets • components on the charger board were running beyond their maximum design power. The transformer itself was not examined, but we would not be surprised if it has inadequate insulation between its primary and secondary. Another relevant video is “Horrific USB power supply fault. (Electrocution risk.)” at: siliconchip.com.au/link/ aaub by YouTuber bigclivedotcom. This video shows a USB charger that was live with mains voltage on the USB outlet side. The fault was found to be related to a defect in the insulation between the primary and secondary of the transformer (see Fig.4). Bargain multimeters: unsafe at any price! There are many cheap multimeters available on eBay, Fake UL, CE and other certifications It is easy to print a certification label on a product, but that does not mean that it has been certified. UL, formerly Underwriters Laboratories (www.ul.com) is a US certification agency with branches in 46 countries, including Australia. Their trademark is widely (but falsely) applied to non-approved items. CE or Conformité Européenne (siliconchip.com.au/link/aaup) is another mark that is widely faked. Correctly applied, it designates compliance with European standards. 16 Silicon Chip • no fuse or high-voltage resistors • a resistor divider for measuring high voltages made using small surface-mount resistors • there is a space for a fuse on the circuit board but none is fitted • writing on the meter case refers to the non-existent fuse • the peak AC voltage on the rectifying diode can exceed the diode’s rating of 1000V • there are no internal protection components The investigator compares this meter with another one (Left): this is the voluntary UL mark for Australia. According to UL, “the UL-AU Mark can be used for a variety of products including residential smoke alarms, fire alarm panels, spa and swimming pool equipment, and lighting products.” Australia’s electronics magazine (Right): the often-faked Conformité Européenne trademark. (Left) these are two of many UL marks available. They’re also widely faked. siliconchip.com.au Fig.5: the PCB from a cheap analog multimeter, rated at 1000V. It has no fuse, narrow PCB track spacing and tiny surface mount resistors, making it inappropriate for use at such a high voltage. he already had with the same model number, and discovered that his older one has utterly different internals and also has a protective fuse and much bigger resistors (see Fig.6). The original is also labelled CAT 1 for its voltage rating, unlike the unit being studied. CAT 1 means that it is for use with devices that are not connected to mains; an honest rating for the original meter. But this label was lacking on the new device. The new meter also has a CE mark indicating European certification, but that is unlikely to be the case. The meter is OK for a beginner but should not be used on any mains or other dangerous voltages. See also the follow-up called “$3 multimeter - high voltage & overcurrent test (smoke and explosion)” at: http:// siliconchip.com.au/link/aaue One very popular low-cost multimeter is the DT-830 series meter, available under many different brands and variations. Like other cheap meters, it’s not suitable for highvoltage or high-current measurements. This meter is also available in kit form. The kit costs more but unlike most of the pre-built versions, has a fuse and uses through-hole resistors. There is an extensive web page describing one version of this meter, the DT-830D at: siliconchip.com.au/link/aauf Fig.7: YouTuber AintBigAintClever demonstrates that the exposed terminals of a mains-operated ‘corn cob’ LED light carry dangerous voltages and currents. The meter indicates a power of 31W and a current flow of 158mA simply from contact with the light. siliconchip.com.au Fig.6: DiodeGoneWild comparing two multimeters with the same model number; the older meter is on the left. Even though they are almost identical externally, the internals are very different. The older meter has a fuse, appropriately sized resistors for higher voltages and is correctly labelled as CAT 1, meaning not suitable for mains connected circuits. Dangerous lights Lights can be a particular safety concern. While current Australian regulations require power outlets to be protected by RCDs, until recently, lighting circuits were not required to have an RCD. If you have an older house without RCD protection of lighting circuits, you may wish to consider installing such protection, and you certainly should have a “safety switch” fitted if you don’t have one at all. A video titled “Dangerous LED “corn cob” lamp test and teardown” can be seen at: https://youtu.be/n3ci4nlKhEk In it, YouTuber “AintBigAintClever” looks at a mainsoperated ‘corn cob’ LED light and finds live voltages on the surface of the device, an obvious shock or electrocution hazard (Fig.7). That video was made in 2014; the corn cob lights available online today appear to mostly have a plastic insulating cover over the LEDs to render them safe. But some of these unsafe devices may still be in service. Note also that this video is from the UK, but we use the same BA22d bayonet fitting at similar voltages. Another video by YouTuber bigclivedotcom, titled “126 LED hydroponic death lamp.” can be seen at: https://youtu. be/QRNYDLp4zdM Fig.8: a mains-derived 49.5V appears at the exposed face of this lamp; a potential shock hazard, as its internal power supply is not isolated from the mains. Australia’s electronics magazine December 2019  17 Fig.9: a teardown and investigation by YouTuber bigclivedotcom of a fish tank light that killed all the fish. This investigation revealed that the 126-LED hydroponic lamp did not have an isolated output, and if a person or plant made contact with the exposed connections, they could receive a shock (Fig.8). Fig.10: a selection of electrode boilers available online, including one sold as a baby bath heater, as looked at by YouTuber bigclivedotcom. Warning! Do not use such devices. They are extremely dangerous. An aquarium light . . . that killed fish able which are exceptionally dangerous because users can come into contact with the electrodes. In the video titled “2.5kW electro baby-cutor. (And dodgy bucket warmer.)” at: siliconchip.com.au/link/aauh YouTuber bigclivedotcom looks at a variety of these units, including one sold as a baby bath water heater (see Fig.10). In another video titled “EEVblog #873 - World’s Most Dangerous Consumer Product!” at: siliconchip.com.au/ link/aaui David L Jones investigates a dodgy water heater he purchased for $3.89 from Hong Kong (Fig.11). Another video called “Suicide Water Heater & Deadly Experiments (Gone Too Far)” at: siliconchip.com.au/link/aauj sees YouTuber DiodeGoneWild testing the limits of another such device by adding salt to the water, with disastrous results (see Fig.12). This could happen under ordinary circumstances. Not even fish are safe from dangerous electrical appliances. YouTuber bigclivedotcom investigated an aquarium light that killed all the fish in the tank (Fig.9). He called the device the “fish-o-cutor”. It could kill people too if placed in a bath, hot tub or swimming pool. See the video titled “Pink plastic LED fish-o-cutor.” at: siliconchip.com. au/link/aaug The device came with false certifications such as CE and a double-insulated marking, but it had continuity between the low voltage outlet of the device and the mains input Neutral terminal. The fault which killed the fish was traced to electrical leakage from the light in the aquarium, through the frame to Earth. Direct water heaters (electrode boilers) An electrode boiler or heater is a device that heats water using two electrodes (for single-phase mains), heating the water between the electrodes by passing current through it. This relies on the water not being pure and therefore conducting electricity. This is a legitimate method of heating water when properly implemented, but since the body of water itself becomes electrically live, safety considerations are paramount. When designed properly, there is no possibility of user contact with the electrodes. Unfortunately, there are versions of these devices avail- Fig.11: a questionable water heater being tested by YouTuber EEVblog (David L Jones). 18 Silicon Chip Mains travel adapters Travellers frequently need an adaptor so they can plug a mains powered device from their home country into another country’s power outlet. These devices generally only provide a mechanical interface from one type of plug to another, but do not convert the voltage. So you need to be sure that your device will work with the mains voltages in the countries you travel to. Many devices will operate from 100-240VAC at 50Hz or 60Hz, which covers virtually all countries. There are many Fig.12: a test by DiodeGoneWild of an electrode boiler water heater, with smoke and flames liberated. Australia’s electronics magazine siliconchip.com.au Fig.13: an unsafe power adapter, as shown on the web page of WA’s Department of Mines, Industry Regulation and Safety. Two consumers received electric shocks using this device. of these devices available, and ones purchased online from overseas have a high likelihood of being dangerous. In August 2017, WA’s Department of Mines, Industry Regulation and Safety issued a warning about an unsafe power adapter intended to allow the mains plug of an appliance of one country to be used in another (Fig.13). The government department only cited one fault with the device, but there were many more. The warning is at: siliconchip.com.au/link/aatu and you can see a video describing the dangers, titled “Dangerous power adaptors” at: siliconchip.com.au/link/aauk YouTuber DiodeGoneWild reviewed the same device in a February 2017 video titled “Universal Travel Shock-dapter (Dangerous Adapter)”, at: siliconchip.com.au/link/aaul This device converts between US, Australian, UK and various European plugs but with no voltage conversion. There is no Earth connection, but it can power appliances that require an Earth. It is also possible to insert some plugs with only one pin inside the adapter and one pin outside, leaving a live pin outside the unit (see Fig.14). Worse still, it is possible to plug the adapter into a European socket and then disengage the UK, US or Australian Fig.14: YouTuber DiodeGoneWild demonstrating a universal power adapter plugged into a European socket, with the live UK pins disengaged and powering a light bulb. pins from the unit which are then live. A child-protection safety shutter over the holes is not functional, and there is no surge protection despite a label that says there is. Apart from travellers, many devices sent to Australia from overseas sellers don’t have an Australian power plug and instead, come with a free adaptor. These are frequently dangerous – see Figs.15 & 16. The applicable Australian/New Zealand Standard for these devices is AS/NZS 3122:2015. Make sure any device you purchase is compliant. Safety compliance labels are shown in Figs.17 & 18. You can spot many non-conforming units straight away because the plug pins are typically not insulated near their base, as is required by the latest standard. Editor’s note: I had one of these at home which came with something I bought, but I decided not to use it as I Fig.16: another US and EU to Australian (or Chinese) adapter. This one also lacks the insulated pin bases and can accept an appliance with an Earth pin which would go beyond the edge of the device and would not make a connection. This one was from eBay, delivered from overseas for A$1.00 plus GST. These are frequently provided for free with mains equipment sent to Australia from overseas sellers. Fig.17: an Australian safety compliance label, showing the approval number. Fig.15: an example of an electrical adapter found on eBay to enable appliances with US, UK or various European plugs to be used in Australia (or China). It accepts the plug of an Earthed appliance but does not itself have an Earth pin. The bases of the pins are also not insulated, as required by the Australian Standard. This one cost A$1.33+GST from overseas. It is also possible to plug just one pin of a device into the socket, rendering the other pin live. siliconchip.com.au Australia’s electronics magazine Fig.18: a regulatory Compliance Mark which may be affixed to a compliant travel adapter. It indicates compliance with applicable Australian requirements. December 2019  19 Figs.20 & 21: by way of contrast, this shows how a three-phase plug and socket should be made to Australian standards; a Clipsal 56P532 plug and 56C532 socket, both rated at 32A, 500V. Fig.19: a Chinese 32A 440V plug and socket that is not compliant with Australian standards. In Australia, threephase power used to be 415V RMS but is now 400V RMS to harmonise with European standards. The 440V rating is the claimed voltage rating of the plug and socket. could see it didn’t meet local electrical rules. But without my knowledge, my wife found it and used it to power an induction cooker. When she complained that the cooker wasn’t working properly, I noticed the adaptor and found it was very hot! I replaced it with a proper travel adaptor and the cooker then worked fine. Don’t leave these poor quality adaptors lying around; just get rid of them. You never know who might try to use them when you aren’t looking! Substandard three-phase plugs and sockets In a video titled “Horror Chinese 32A 440V Power Outlet and Plug Autopsy” at: siliconchip.com.au/link/aaun YouTuber Aussie50 looked at a three-phase mains power plug supplied with factory equipment imported from China. The 11kW machine, as supplied, had no Earth wire (see Fig.19). The following problems were found with the supplied plug: • insufficient clearance between power pins and screws used to hold the unit together • wiring was too small a gauge • clamp to secure original cable ineffective, as the case is made of a material that was too hard to compress, so the cable could move freely in and out of the plug • power pins of plug free to rotate and come loose • no isolation barriers between wires • the nuts that hold the wires on can come loose • wires were tinned before being screwed in (not a good idea) • the washers used with the nut to hold the wires on were made of recycled material with poor conduction • the Earth pin does not enter the socket before other live pins, so phases can connect before Earth • questionable insulation of supplied wires, probably rubber-based with no or little fire retardant • pins too thin to fit properly into an Australian threephase outlet Safety problems with a matching socket purchased separately included: • no sideways wire entry • cheap plastic tooling and moulding • Earth socket made of cheap, fragile metal which is easily broken 20 Silicon Chip • Earth pin on top as per Chinese standard rather than the bottom as with Australian standard • terminals not isolated from each other • nothing to prevent foreign matter falling into pin hole • nothing to prevent long wires from shorting against a metal backing panel Powerboards From time to time, we get letters from SILICON CHIP readers complaining about the poor quality of electrical power boards they have purchased. It is not clear if these boards are genuine ones made to Australian standards or counterfeits. Powerboard safety is a serious and prevalent issue. In the five months prior to 22nd December 2014, the Australian Competition and Consumer Commission received 13 recall notifications for these devices and urged consumers to inspect all their power boards and double adapters. See the list of recalled products at: siliconchip.com.au/link/aatv These recalls arose because the original samples of supplied products received approval for sale in Australia, but there were post-approval changes in the design or manufacturing process which rendered them no longer safe. Powerboards are required to be fitted with an overload protection device to avoid overheating and becoming a fire risk. The applicable Australian and New Zealand Standard for domestic power boards is AS/NZS 3105:2014, “Approval and test specification - Electrical portable outlet devices”. Mains power plugs and sockets from Australian manufacturers can be considered safe, but consumers should be aware of the possibility of fake items that might find their way onto the market. Also, non-compliant plugs and sockets should never be connected to Australian mains power. Copper or steel wire? Some products from China use steel rather than copper for conductors in electrical wire. The steel is much cheaper than copper and may be plated with copper to give it the appearance of being solid copper. A simple test to establish the composition of suspect conductors is with a magnet (see Fig.22). Steel is a substantially worse electrical conductor than copper and less malleable, so these wires will make bad and possibly dangerous high-resistance crimp-style connections. Dangerous battery chargers Just as you should only buy rechargeable batteries from a reputable source (there are millions of fakes out there!) it’s essential to buy a good quality battery charger, especially for lithium-ion cells. An inappropriate charger can cause the battery to catch fire. In a video titled “Li-Ion cell charger with (too) simple Australia’s electronics magazine siliconchip.com.au Fig.22: ever seen magnets stick to copper? They will if the “copper” wire is actually made of much cheaper steel with copper coating! This was determined with a magnet by Blogger “nophead”; see: siliconchip.com.au/link/aatw design. With schematic. Charges to 4.45V!” at: siliconchip. com.au/link/aauo YouTuber “DiodeGoneWild” describes a lithium-ion battery charger of Chinese origin, purchased on eBay for US$1.19 including shipping to Europe. It had no fuse, no inrush current limiting resistor, no interference filter, questionable separation between low voltage and mains PCB tracks (1mm) and the output voltage was too high due to the use of a zener diode as a shunt regulator (see Fig.23). The device charged the battery to 4.45V per cell. Most lithium-ion batteries should not be charged beyond 4.2V (follow manufacturer’s instructions). Beyond 4.3V, metallic lithium will be plated onto the anode, and the cathode starts to produce CO2 gas. For cells with a sealed metal container, such as the 18650 types commonly used in laptops or Tesla cars, once the cell pressure reaches 1000-1380kPa (145-200psi), the current interrupt safety device (if fitted!) should stop the flow of Look out for dodgy mains cords This one is not directly applicable to antipodeans, as it involves a UK-style mains cord. But you could possibly buy equipment on the internet and get a cable with a similar problem. YouTuber Jim Conner’s video, titled “Illegal and Deadly imported UK Plug Rant” can be seen at: siliconchip.com.au/link/aaum UK power plugs are unusual in that they always incorporate a fuse. This design has its origins in the second world war, due to a shortage of copper. To save copper wiring, power outlets were put on a 32A “ring main” with 10A rated outlets. In other words, the power outlets are chained, rather than being individually wired back to a distribution panel. Therefore, each 10A outlet needed a 10A fuse; omitting it would be like omitting a fuse or circuit breaker at the distribution panel in an Australian system. In this particular example, the UK plug supplied had no fuse, and the wire in the cable could not handle the 10A claimed. In the video, the cable melted while passing just 5.5A! Even if it had been a compliant plug with a 10A fuse, the cable could have started a fire. So watch out for suspiciously thin mains cords. But even that may not be a giveaway, as thin wire could be ‘bulked up’ with siliconchip.com.au Fig.23: the circuit of the lithium-ion battery charger that charged to a dangerously high voltage. The poor voltage regulation is due to the zener diode at lower right. The voltage across a zener diode is dependent on the current going through it and therefore will vary as the load changes due to the battery charging. It is therefore unsuitable for this application. current. But if the pressure rises further, the safety membrane on some lithium batteries bursts at about 3450kPa (500psi) and flame may be “vented” (see photo on p14). This is another reason to always use good quality protected cells (those with a protection circuit board) if using lithium-ion batteries in your project. Note that lithium-ion cells, especially those with a metal can such as 18650s, are safe if used and charged correctly. Electrically heated “suicide” showerheads Direct electrically heated shower heads would not be legal in Australia or most other Western countries, but are nevertheless available online for Australians to purchase. In one word: DON’T! They are extremely popular in Central and South America, and also available in Africa and Asia, where central hot water systems are less common or non-existent, as are strict electrical standards (see Figs.24-27). thicker insulation. In general, it’s best to avoid foreign-supplied mains cables entirely. You never know whether they will meet their claimed specifications. Australia’s electronics magazine December 2019  21 Fig.24: a screengrab from DiodeGoneWild’s teardown video of a ‘suicide’ showerhead, showing the heating elements in the water stream. What little safety these devices have relies on water resistivity being below a certain threshold, which may not be the case where water mineral content is high. They also rely on a functional Earth connection for safety, but many installations don’t have one or don’t connect it. Australian tourists may encounter these when overseas, so be very careful. Not surprisingly, people have died from using these units. See the video series by YouTuber DiodeGoneWild starting with the one titled “Electric heated ‘suicide’ shower PART 1 - teardown & calculations” at: siliconchip.com.au /link/aauq In this video, a popular ‘suicide’ shower head was examined, and electrical measurements were made of an installed unit. The findings were as follows: Water is heated ‘on the fly’. There is a high and low power switch with a stated 5400W power consumption on high. Wires are spot welded to the device, meaning there is no way to fit longer wires. The very short supplied wires have to run to a terminal block or similar device, mounted close to the showerhead, which may be exposed to water. The heating element is bare and exposed to water rather than enclosed in a sheath; there is a possibility that with insufficient water flow, the device could overheat and burn. The metal switch contacts are bare copper and not plated with tin or nickel to reduce corrosion. The investigator could only get the device to operate by Fig.25: a typical installation (one of the better ones!) of a ‘suicide’ showerhead in Brazil. The Earth wire is not connected. Image source: Tweet by AbwesenTweets. 22 Silicon Chip Fig.26: in bigclivedotcom’s teardown of the suicide shower head, he discovers that the bare end of the “Earth wire” in the outlet water stream is covered with silicone, so it is not effective. The purpose of this oddly placed wire is to conduct any residual current to Earth before it reaches the user; at least, if there is a functional Earth connection. connecting the device to a circuit without an RCD; 190mA current flowed through the Earth on the high setting and 130mA on the low setting. Surprisingly, there was no shock to the tester with one hand directly under the showerhead and the other hand on an Earthed plate, but this was with a proper Earth installed to the unit. With no Earth connected, about half of the mains voltage was present directly at the outlet of the water and 25mA of current would flow to Earth. The tester received an unpleasant sensation with his finger directly under the water outlet, with a few milliamps flowing through his body. The current flow dropped off rapidly as he moved his fingers away from the outlet. The showerhead would work with an RCD-protected circuit if the Earth wire was not connected, but in this case, the RCD would not trip despite the current flowing through his body. Given all of the above, the investigator concluded that if the device was correctly Earthed (that’s a BIG if in the sort of places these devices are installed), it is almost impossible to get a shock, assuming there are no faults. However, with no Earth connected, it is definitely possible to get a shock from it. Fig.27: a ‘suicide’ shower-head in Latin America with no top cover and the Earth wire not connected, just hanging in midair. Image source: http://johnnyvagabond.com/travel-tips/ survive-suicide-shower/ Australia’s electronics magazine siliconchip.com.au We recommend avoiding this type of shower head on your travels. You never know how well they have been installed or maintained. YouTuber bigclivedotcom also reviewed one of these units in a video titled “Inside a heated shower head (suicide shower)” at: siliconchip.com.au/link/aaur (see Fig.26). He made additional observations that Western tourists to the countries that use these devices tend to be taller than the locals that use them, and therefore their heads are closer to the units. So they are more likely to experience electrical sensations (or worse). Also see Australian YouTuber David L Jones’ look at the product, in a video titled “EEVblog #873 - World’s Most Dangerous Consumer Product!” at: siliconchip.com.au/ link/aaui Finally, in a video titled “Teardown of a UK electrically heated shower unit” at siliconchip.com.au/link/aaus bigclivedotcom looks at an electrically-heated shower unit made to UK standards. The water is heated in a separate space, rather than in the head, and it has extensive safety features and is built to a high quality. We’ve seen 10A extension leads where the plastic has simply melted, leaving all pins exposed. While you can’t easily check the socket, if the pins on your extension lead are tarnished or corroded, we’d be taking to them with a wire brush or emery cloth to bring them back up to bright, shiny condition. If you cannot do that, it’s best to replace the plugs and sockets with new ones. But take care with the wiring – follow the instructions on the packs! And finally! We couldn’t resist showing this photo we found on the ’net. No, it wasn’t set up just for the photo! A more dangerous jerry-rig is hard to imagine, even more dangerous than using one of the dodgy adaptors we’ve talked about in this feature. One flash and you’re ash, and all that . . . SC Extension lead problems All extension leads sold in Australia must be approved and labelled (at least at time of purchase) with their current rating. “Everyone knows” (!) you shouldn’t use a damaged lead – if it’s nicked it should be discarded. Most leads are rated for 7.5A or 10A; some (usually sold as “caravan leads”) are rated at 15A and have a thicker Earth pin to prevent them being used on a standard (10A) GPO. But have you noticed your extension leads, or more correctly the plug and socket, are very hot after use with a high power device? Take a look at the pins on the plug; are they tarnished or weathered? That creates a higher-than-normal resistive connection, and high resistance usually equals heat – lots of it! SILICON CHIP * Every effort is made to keep all boards in stock. In the event that stocks run out, there is normally only a two week delay in restocking. Applies to all boards since 2010, excepting those where copyright has been retained by the author. S ILICON C HIP LCR Wallchart You’ll wonder how you got by without one! INTERNET Credit/Debit Card* etc siliconchip.com.au Fig.28: Temporary Australians! Nail clippers used to adapt a US plug to an Australian power outlet! ONLINESHOP . . . it’s the shop that never closes! 24 hours a day, 7 days a week . . . it’s the shop that has all recent SILICON CHIP PCBs – in stock* . . . it’s the shop that has those hard-to-get bits for SILICON CHIP projects . . . it’s the shop that produces those professional laser-cut acrylic cases . . . it’s the shop that has all titles in the S ILICON C HIP library available! . . . it’s the shop which maintains back issues for sale (until they run out!) . . . it’s the shop where you can get a project reprint if back issues unavailable . . . it’s the shop where you can place an order for a subscription (printed or on-line – or both!) from anywhere in the world! . . . it’s the shop where you can pay on line, by email, by mail or by phone Australia’s own mighty MicroMite PLUS: Explore 100, Explore 64 and projects PAYPAL (24/7) Use your PayPal account silicon<at>siliconchip.com.au And all those hard-to-get project components: Currawong Valve Amplifier SidRadio Parts eMAIL (24/7) with order & credit card* details silicon<at>siliconchip.com.au *Mastercard or Visa only The complete Radio, TV & Hobbies on one DVD! GPS Units (as used in many projects) MAIL (24/7) your order to PO Box 139 Collaroy, NSW 2097 PHONE (9-5, Mon-Fri) Call (02) 9939 3295 with order & credit card* details Browse online now at www.siliconchip.com.au/shop siliconchip.com.au Australia’s electronics magazine December 2019  23