Electrical safety

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.

 

25 Comments

  1. Tomi Engdahl says:

    National electrical safety code to be opened for comment
    http://www.csemag.com/single-article/national-electrical-safety-code-to-be-opened-for-comment/c945365cd409aae4ba6bf42a557bd1bc.html

    A pre-print of the 2017 national electrical safety code (NESC) will open for comment 100 years after the NESC was first introduced. IEEE-SA will publish and open commentary on the preprint of proposed changes to the 2017 Edition of the NESC beginning Sept. 1, 2014.

    Reply
  2. Tomi Engdahl says:

    Celebrating 100 Years of Safety & Interoperability
    National Electrical Safety Code® (NESC®)
    http://standards.ieee.org/about/nesc/100/index.html

    Reply
  3. Tomi Engdahl says:

    SESKO wants opinions on electrical work safety standard SFS 6002 proposals

    Electrical and electronics industry standards organization SESKO has completed a proposal for a new electrical safety standard. The standard proposal is for all to comments on SFS’s referral service at lausunto.sfs.fi . The deadline for delivery of the opinion is the 28th day of November, after which the Standardisation Committee deals with the feedback meeting.

    The revised standard SFS 6002 will enter into force in early 2015, the Standard has not been revolutionary changes, but it has been improved across the board up to date. At the moment, the current standard is from the year 2004.

    The new standard will include instructions on emergency measures, as well as the arc of the risk guidelines.

    The new standard also has a vehicle in the field of attachment, which contains electric and hybrid vehicles on the security guidelines.

    Source: http://etn.fi/index.php?option=com_content&view=article&id=1776:sesko-haluaa-lausuntoja-sahkotyon-turvallisuusstandardiin&catid=13&Itemid=101

    Reply
  4. Tomi Engdahl says:

    New electrical work safety standard was published in Finland

    Finland down electrical safety standard SFS 6002 have been published in the third edition. Previous standard version of the year 2005.

    The standard came into effect immediately and is available in the Organisation for Standardisation SFS’s online store ( http://sales.sfs.fi )

    Source: http://www.etn.fi/index.php?option=com_content&view=article&id=2681:uusi-sahkotyoturvallisuusstandardi-julkaistiin&catid=13&Itemid=101

    Reply
  5. Tomi Engdahl says:

    Arc flash relays meet code compliance
    Revised NEC 240.87 requirements make mitigation easier to achieve.
    http://www.controleng.com/single-article/arc-flash-relays-meet-code-compliance/811537f80ab33a1d57ee181ca0914aab.html

    Besides wanting to comply with state regulations, managers knew that insurance providers expect equipment to meet minimum design standards, which the NEC provides. They discovered that the code change makes it easier to protect workers and equipment from arc flash hazards.

    Paragraph 240.87 of the 2011 edition of the NEC, which was titled Non-instantaneous Trip, said that whenever using a circuit breakerwith a rating of 1,200 A or higher (or one that could be adjusted to 1,200 A or higher) that did not have an instantaneous trip function, one of the following was required:

    1. Zone-selective interlocking
    2. Differential relaying
    3. An energy-reducing maintenance switch with local status indicator.

    Zone-selective interlocking addresses a shortcoming of selective coordination. It involves interconnecting downstream and upstream circuit breakers: If a short circuit or ground fault occurs on a branch circuit, the breaker feeding it will trip instantaneously, and simultaneously send a signal to the breaker just upstream, telling it to use its time-delay function instead of tripping instantaneously.

    Differential relaying uses current transformers at the inputs and outputs of the electrical equipment being protected (zones). When a fault occurs, the zone in which the input and output currents do not match is the location of the fault, and the appropriate breaker is tripped. This is complicated and expensive and takes up a fair amount of space.

    An energy-reducing maintenance switch manually sets the current pickup lower and the time delay faster, to trip the breaker feeding a panel as fast as possible while someone is working on it. If there is an arc flash, the breaker should trip instantaneously and limit the energy delivered. This reduces the level of PPE required for the panel. The switch must be activated manually before beginning the maintenance activity to provide protection, and deactivated afterward to prevent future nuisance tripping or miscoordination.

    Reply
  6. Tomi Engdahl says:

    Cheap $8 Ebay Power Supply vs $85 Cosel Power Supply
    https://www.youtube.com/watch?v=71NWT5vrbk8

    Reply
  7. Tomi Engdahl says:

    Reviewing, analyzing NEC 2014 changes
    Changes in and additions to the NFPA 70: National Electrical Code (NEC) have a significant impact on commercial and industrial facilities.
    http://www.csemag.com/single-article/reviewing-analyzing-nec-2014-changes/03b795fd3cc1c7384acfee29c29d7145.html

    Every 3 yr, NFPA 70-2014: National Electrical Code (NEC) is updated and released. However, not all states immediately adopt the new code changes. The adoption by many states doesn’t typically occur until the year after the latest version is released.

    There are several new articles as well as some noteworthy changes included in the 2014 edition of the NEC. Some changes have had a significant impact on the electrical trade. An example is a codewide change to raise the maximum voltage level from 600 V to more than 1,000 V, primarily driven by the higher voltages in wind turbine and photovoltaic (PV) systems.

    Some of the code additions and modifications have substantial impact on commercial and industrial facilities.

    NEC 2014 change—Article 210: Branch Circuits; Section 210.13 Ground-Fault Protection of Equipment:

    Each branch-circuit disconnect rated at 1,000 A or more and installed on solidly grounded wye electrical systems of more than 150 V to ground, but not exceeding 600 V phase-to-phase, shall be provided with ground-fault protection of equipment in accordance with the provisions of 230.95.

    Exception No. 1—The provisions of this section shall not apply to a disconnecting means for a continuous industrial process where an unorderly shutdown will introduce additional or increased hazards.

    Exception No. 2—The provisions of this section shall not apply if ground-fault protection of equipment is provided on the supply side of the branch circuit and on the load side of any transformer supplying the branch circuit.

    Conductor sizing

    NEC 2014 change—Article 210: Branch Circuits; Part II, Branch Circuit Ratings; Section 210.19 Conductors—Minimum Ampacity and Size:

    Subsection (A), Branch Circuits Not More Than 600 V, (1) General: Branch-circuit conductors must have an ampacity of not less than the maximum load to be served. Conductors shall be sized to carry not less than the larger of Article 210.19(A)(1)(a) or (b).

    (a) Where the branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum branch-circuit conductor size shall have allowable ampacity not less than the noncontinuous load plus 125% of the continuous load.

    (b) Minimum branch-circuit conductor size shall have an allowable ampacity not less than the maximum load to be served after the application of any adjustment or correction factors.

    Exception—If the assembly, including the overcurrent devices protecting the branch circuits, is listed for operation at 100% of its rating, the allowable ampacity of the branch-circuit conductors shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load.

    Reply
  8. Tomi Engdahl says:

    The most important and most comprehensive standard for real estate in electrical installations in Finland is low voltage or standard SFS 6000. The standard pre-group work is nearing completion and the standard proposal leaves circulated for comment in early 2017. Valid standard will be in autumn 2017.

    the wider the earth leakage protection residential apartments.
    Residual current device also residential flats for lighting

    Also, the fault protection requirements become stricter: all pistorasiaryhmäjohdoilta required in the future 0.4-second switch-off time is always of the protection device to the rated current of 63A.

    Arc fault protection and protective cooker as preferred

    Destinations where a fire can cause a particular risk, will be recommended for protection under the arc fault protection. Such premises include facilities as well as facilities where people sleep

    Arc fault protection is required for new installations in Germany and the United States have been in use for decades.

    Standard reform is also reflected in the photovoltaic systems and electric vehicle charging points and an increased demand for these figures have been revised thoroughly.

    Source: http://etn.fi/index.php?option=com_content&view=article&id=5503:pienjannitestandardi-uudistuu-ensi-vuonna&catid=13&Itemid=101

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  9. Tomi Engdahl says:

    Electrical Safety Act requires more

    Tukes is now drawn up a brochure explaining the new requirements of the Electrical Safety Act’

    The new Electrical Safety Act requires the property or the building owner or the holder to take care of the maintenance of electrical installations. Maintenance is ensured also in properties, which do not need to make periodic inspections.

    Electrical installation and electrical centers of the components wear out and come to the end of their useful life over time. Worn, damaged or in poor condition installations can cause power outages in addition to the risk of fire and electric shock. Building fires about one-third comes from electrical appliances or installations. Electrical fires are about 20 people died and electric strikes to 2-4 people a year. With good maintenance and regular inspections can reduce the risks considerably.

    The new Electrical Safety Act electrical system of classification must be simplified and clarified.

    Inspection intervals should be simplified so that the clearance is 10 years for all other items except electricity distribution company networks, where it is five years.

    Source: http://www.etn.fi/index.php/13-news/5779-saehkoeturvallisuuslaki-vaatii-aiempaa-enemmaen

    Reply
  10. Tomi Engdahl says:

    The Importance of Electrical Safety
    http://hackaday.com/2017/03/01/the-importance-of-electrical-safety/

    Everything you do bears some risk of getting you hurt or killed. That’s just the way life is. Some people drown in the bath, and others get kilovolt AC across their heart. Knowing the dangers — how drastic and how likely the are — is the first step toward mitigating them. (We’re not saying that you shouldn’t bathe or play with high voltages.)

    While 30 V is generally the threshold where skin resistance alone isn’t enough, you can get shocked badly by only 12 V if you’re sweaty and wearing a tight metal watchband. Do the math.

    The Importance of Electrical Safety
    Chapter 3 – Electrical Safety
    https://www.allaboutcircuits.com/textbook/direct-current/chpt-3/importance-electrical-safety/

    How AC affects the body depends largely on frequency. Low-frequency (50- to 60-Hz) AC is used in US (60 Hz) and European (50 Hz) households; it can be more dangerous than high-frequency AC and is 3 to 5 times more dangerous than DC of the same voltage and amperage. Low-frequency AC produces extended muscle contraction (tetany), which may freeze the hand to the current’s source, prolonging exposure. DC is most likely to cause a single convulsive contraction, which often forces the victim away from the current’s source. [MMOM]

    REVIEW:
    Electric current is capable of producing deep and severe burns in the body due to power dissipation across the body’s electrical resistance.
    Tetanus is the condition where muscles involuntarily contract due to the passage of external electric current through the body. When involuntary contraction of muscles controlling the fingers causes a victim to be unable to let go of an energized conductor, the victim is said to be “froze on the circuit.”
    Diaphragm (lung) and heart muscles are similarly affected by electric current. Even currents too small to induce tetanus can be strong enough to interfere with the heart’s pacemaker neurons, causing the heart to flutter instead of strongly beat.
    Direct current (DC) is more likely to cause muscle tetanus than alternating current (AC), making DC more likely to “freeze” a victim in a shock scenario. However, AC is more likely to cause a victim’s heart to fibrillate, which is a more dangerous condition for the victim after the shocking current has been halted.

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  11. Tomi Engdahl says:

    Safe Practices
    Chapter 3 – Electrical Safety
    https://www.allaboutcircuits.com/textbook/direct-current/chpt-3/safe-practices/

    All properly designed circuits have “disconnect” switch mechanisms for securing voltage from a circuit. Sometimes these “disconnects” serve a dual purpose of automatically opening under excessive current conditions, in which case we call them “circuit breakers.” Other times, the disconnecting switches are strictly manually-operated devices with no automatic function. In either case, they are there for your protection and must be used properly. Please note that the disconnect device should be separate from the regular switch used to turn the device on and off. It is a safety switch, to be used only for securing the system in a Zero Energy State

    With the disconnect switch in the “open” position as shown (no continuity), the circuit is broken and no current will exist. There will be zero voltage across the load, and the full voltage of the source will be dropped across the open contacts of the disconnect switch.

    For maximum safety of personnel working on the load of this circuit, a temporary ground connection could be established on the top side of the load, to ensure that no voltage could ever be dropped across the load

    Reply
  12. Tomi Engdahl says:

    Looking Mains Voltage In The Eye And Surviving
    http://hackaday.com/2016/05/11/looking-mains-voltage-in-the-eye-and-surviving-part-1/

    It is often a surprise to see how other people react to mains electricity when they encounter it in a piece of equipment. As engineers who have dealt with it both personally and professionally for many years it is easy to forget that not everyone has had that experience. On one hand we wince at those who dive in with no fear of the consequences, on the other we are constantly surprised at the number of people who treat any item with more than a few volts in it as though it was contaminated with radioactive anthrax and are scared to even think about opening it up.

    Reply
  13. Tomi Engdahl says:

    Man dies while charging iPhone in bath
    https://www.cnet.com/news/man-dies-after-charging-iphone-in-bath-electrocution/#ftag=CAD590a51e

    A British man plugged his iPhone into an outlet via an extension cord and appears to have rested the charger on his chest in the bath.

    “We found an iPhone plugged into the extension cable and then the charger element in the bath,” PC Craig Pattinson told an inquiry into Bull’s death.

    death was caused accidental electrocution.

    extremely concerned that people didn’t realize that phones were as dangerous near water as, say, hairdryers.

    The coroner, Dr. Sean Cummings, told the inquiry: “They should attach warnings. I intend to write a report later to the makers of the phone.”

    Reply
  14. Tomi Engdahl says:

    Arc fault protection is recommended to prevent fires

    Next fall will come into force SFS 6000 electrical installation standard recommends that certain spaces in which a fire can cause a particular risk, protected with arc fault protection devices. Arc fault protection is installed in the electrical cabinet, in Finland so far quite unknown protective device, the purpose of which is to prevent electrical fires caused by arcing faults.

    Modern arc fault protection (English arc fault detection device, AFDD or arc fault circuit interrupter, AFCI) will react as well as serial (poor connection, or the broken conductor inflammable) that (for example, the insulation fault between a phase and the neutral conductor due to inflammable) arc-parallel. Identification is based on the arc characteristic of high frequency power monitoring and analysis of the components: the device is structurally more complex than a simple circuit breaker or circuit breaker.

    Arc fault protection is applied for in connection with the MCB, and the standard it is recommended that they protect
    - Properties containing spaces to be used for sleeping (in practice, residential buildings)
    facilities, which is handled or stored in the course of fire from materials
    - Spaces containing combustible materials, building materials
    - Fire-spreading structures
    - Spaces containing priceless objects.

    This is only a recommendation, and if the experiences are positive, sheds probably later required. In practice, the only mandatory shelters lead to massive deployment – this was observed in the case of residual current circuit breakers.

    Source: http://www.etn.fi/index.php/13-news/6066-valokaarivikasuojaa-suositellaan-estamaan-tulipaloja

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  15. Tomi Engdahl says:

    Electrical fires killed 21 people in 2016

    Last year was an electrical fire fatalities in respect grim. Tukes, the sixteen fire caused the death of 21 people and two died in a fire a total of five children. In the previous year electrical fire deaths was 16, and in the 2010s the victims has been an average of 15 per year.

    Electric devices, or – installing the ensuing fires recorded in the rescue PRONTO-Register last year 2660th Most electrical fires caused the devices were cookers and ovens (971 units), lamps (178) and heaters (122).

    Source: http://www.etn.fi/index.php/13-news/6065-sahkopaloissa-kuoli-21-ihmista

    Reply
  16. Tomi Engdahl says:

    Tracking Index Test
    http://hackaday.com/2017/04/06/tracking-index-test/

    What is Tracking ?

    Tracking is a surface phenomena on an insulating material. When you have two conducting terminals or tracks at a high voltage (higher than 100 VAC) separated by an insulator, a combination of environmental factors such as dust, moisture and thermal cycling could cause minute leakage currents to flow on the surface between the conductors. Over time, the deposits carbonize and the surface current increases. Eventually, a carbon track forms over the surface of the insulator making it conductive at a particular “tracking” voltage. Finally, a short circuit is created between the two conductors which may also lead to fire. Worse, it’s possible that the tracking current could be lower than the rating of the protective fuse in the appliance, which will prevent the electrical supply from being cut off, creating a fire hazard. Tracking can be avoided by using the right kind of insulating materials and adequate creepage and clearance distances. One of the reasons for adding a slot between adjacent high voltage terminations or tracks on a PCB is to take care of tracking.
    Test Standards

    It’s impossible to conduct such tests according to real world conditions, so a standardized procedure is needed which can produce results that allow different materials to be compared. The IEC’s Technical sub-committee 15E was previously entrusted with the work of creating and maintaining tracking index methods and standards. Considering the importance of this standard and its wide implications, this work is now handled by TC 112 — Evaluation and qualification of electrical insulating materials and systems.

    TC 112’s document IEC 60112 defines a “standardized method for the determination of the proof and the comparative tracking indices of solid insulating materials” for voltages up to 600 VAC

    Reply
  17. Tomi Engdahl says:

    Fire Hazard Testing
    http://hackaday.com/2017/03/15/fire-hazard-testing/

    How do you know that new appliance you bought won’t burn your house down? Take a look at any electrical appliance, and you’ll find it marked with at least one, and most often, several safety certification marks such as UL, DIN, VDE, CSA or BSI. Practically every electrical product that plugs into utility supply needs to go through a mandatory certification process to ensure it meets these conformity test requirements. Some examples include domestic and industrial electrical appliances, tools, electrical accessories, consumer electronics and medical electronics.

    The IEC works by distributing its work across almost 170 Technical Committees and Subcommittees which are entrusted with the job of creating and maintaining standards. One of these committees is “TC89 Fire hazard testing” whose job is to provide “Guidance and test methods for assessing fire hazards of electro-technical equipment, their parts (including components) and electrical insulating materials”. These tests are why we feel safe enough to plug something in and still sleep at night.

    Practically all electrical products need to confirm to this set of tests as part of their “Type” test routine. This committee produces fire hazard testing documents in the IEC 60695 series of standards. These documents range from general guidelines on several fire hazard topics to specific instructions on how to build the test equipment needed to perform the tests. It’s interesting to see how some of these tests are carried out and the equipment used. Join me after the break as we take a look at that process.

    Reply
  18. Tomi Engdahl says:

    In many electrical goods store in circulation within the meaning of testers for testing grounded SCHUKO power outlets, which can quickly test whether the outlet is connected properly sold. with them must be especially careful, because the sale is still dangerous testers.

    SCHUCO outlet when properly connected to the protective conductor (PE) is connected to the shield contact, the left contact of the neutral conductor (N) and the right side of the phase conductor (L). If it is implemented in a two-wire system, the old property, the socket is only two wires: the phase conductor (L) and the combined neutral and protective conductor (PEN). In this case, socket shielding contact reset or connect it to the line stretch of the neutral conductor.

    The market has roughly two types of SCHUKO outlet tester: first type is touching a metal pin intended for grounding the testing, the second is only three indicator lamps.

    The ones with grounding touch pin sukotester detects an invalid ground connection, when the user touches the ground test pin.

    Electrical Safety Act, the electrical installation is necessary always an initial inspection, even if they are minor work such as replacing a broken socket. Low-voltage part of the standard 6000-6: the number 61 contains the requirements

    Source: http://www.etn.fi/index.php/13-news/6183-varo-markkinoilla-hengenvaarallisia-pistorasiatestereita

    Reply
  19. Tomi Engdahl says:

    We’ve Got It Down PAT: Appliance Electrical Safety Testing
    http://hackaday.com/2017/05/04/appliance-electrical-safety-testing-weve-got-it-down-pat/

    Everywhere we look in our everyday lives, from our bench to our bedroom, there are the ubiquitous electrical cords of mains-powered appliances. We don’t give our electrical devices a second thought, but in addition to their primary purpose they all perform the function of keeping us safe from the dangerous mains voltages delivered from our wall sockets.

    Of course, we’ve all had appliances that have become damaged.

    In most countries there are electrical regulations which impose some level of electrical safety on commercial premises. Under those regulations, all appliances must be regularly tested, and any appliances that fail the tests must be either repaired or taken out of service

    Consider Both Physical and Electrical

    The PAT test has several parts, of which some are physical and some are electrical. A competent electrical engineer with a well-stocked bench could probably create a set-up to perform the electrical tests themselves, but for convenience and calibration they are invariably combined together in an application-specific self-contained unit, the PAT tester.

    The first part of a PAT test is always a visual one. Inspect the appliance, look for physical damage.

    Once the physical tests have been passed, it is time to turn to the PAT tester for the electrical tests. The computerised models will normally have a set of pre-programmed tests for different types of appliances rather than the physically selectable tests of the physical models, but the basic tests themselves are the same. There will be an earth bond test, an earth leakage test, and an insulation test.

    The earth bond test is for non double-insulated appliances, and ensures that the earth pin on the plug has a good quality connection to any exposed metal parts of the appliance. An earth bond lead from the tester is clipped to external metalwork, and a high DC current of about 40 A is passed between it and the earth pin on the socket. The aim of the test is to ensure that the earth connection has a suitably low resistance, and can take a high current without burning out.

    The leakage test is designed to ensure that any leakage from the live supply to the earth wire or to the exposed metal parts of the appliance is at acceptably low levels.

    The insulation test applies a very high voltage, in the order of 500 V, to the appliance, and measures the insulation resistance, which should be in the very high M ohm range.

    Reply
  20. Tomi Engdahl says:

    Electrical test instruments: Safety is still the first tool
    http://www.controleng.com/single-article/electrical-test-instruments-safety-is-still-the-first-tool/b95ac4bcc5f550f9e071d8a57f3618f2.html

    Safety is paramount with electrical test instruments and great care must be taken when using equipment or understanding the codes involved.

    There is a great deal of attention devoted to safe work practices during electrical construction, maintenance and repair work. Industry electrical publications regularly report on safety issues, including the use of the proper tools and equipment used for energized and de-energized work, as well as utilizing the correct personal protective equipment (PPE) for each workplace situation.

    Electrical test instruments are given very little discussion, if any, in safety articles. Examples include using the wrong test instruments or improperly using them, which can have catastrophic results. Some of the most frequently used test instruments include noncontact voltage testers, multimeters, insulation testers and ground-resistance testers. The issue with using a non-contact or proximity device is that the requirement to test a circuit to ensure that it is de-energized requires the circuit to be tested phase-to-phase and phase-to-ground, which cannot be done using this type of tester.

    When electrical safety is discussed, the subjects of shock, arc flash, and arc blast dominate the discussions. One question is often asked: “How do I identify when these hazards are present, or likely to be present, when I am using electrical test instruments on electrical circuits and equipment?”

    When conducting voltage verification, for energized and de-energized work, the electrical worker must select the right test instruments and equipment applicable to the work to be performed. As a minimum, these should include the following:

    Voltage indicating instrument suitable for conditions
    Environment
    Correct CAT category I, II, III, or IV
    Continuity test instrument
    Insulation resistance test instrument.

    All test instruments include specific manufacturer’s operational instructions. Test instruments must be certified and display a label of an independent verification lab, such as UL, CSA, CE, ETL or TÜV. Make sure all meters, test leads and probes have an adequate category (CAT) safety rating. Sometimes, the only thing standing between an electrical worker and an unexpected spike is their meter and test leads. If you use the wrong equipment with the wrong voltage, you could be putting yourself and others at risk. So, before conducting any test, make sure your choice of instrument is correct.

    The following additional requirements apply to test instruments, equipment, and all associated test leads, cables, power cords, probes, and connectors:

    Must be rated for circuits and equipment where they are utilized.
    Must be designed for the environment to which they will be exposed and for the manner in which they will be utilized.
    Must be visually inspected for external defects and damage before each use. If there is a defect or evidence of damage that might expose an employee to injury, the defective or damaged item shall be removed from service.

    When test instruments are used for testing the absence of voltage on conductors or circuit parts operating at 50 volts or more, the operation of the test instrument must be:

    Verified on a known voltage source before an absence of voltage test is performed.
    Test for the absence of voltage on the de-energized conductor or circuit part. A zero reading might mean that no voltage is present during the testing, or it could mean that the instrument has failed.
    Verified on a known voltage source after an absence of voltage test is performed.

    This verification primarily applies to conductors or circuit parts operating at 50 volts or more. However, under certain conditions (such as wet contact or immersion) even circuits operating under 50 volts can pose a shock hazard.

    Electrical safety checklist

    The fundamentals of electrical safety can be overlooked, especially by seasoned electricians. It’s worth reviewing a few safety tips, both for the novice electrician and the veteran:

    Use a meter that meets accepted safety standards for the environment in which it will be used.
    Use a meter with fused current inputs and be sure to check the fuses before making current measurements.
    Inspect test leads for physical damage before making a measurement.
    Use the meter to check continuity of the test leads.
    Use test leads that have shrouded connectors and finger guards.
    Use meters with recessed input jacks.
    Select the proper function and range for your measurement.
    Be certain the meter is in good operating condition.
    Follow all equipment safety procedures.
    Always disconnect the “hot” (red) test lead first.
    Don’t work alone.
    Use a meter that has overload protection on the ohms function.
    When measuring current without a current clamp, turn the power off before connecting into the circuit.
    Be aware of high-current and high-voltage situations and use the appropriate equipment, such as high-voltage probes and high-current clamps.

    Reply
  21. Tomi Engdahl says:

    Dangers of Using Electronics in Bathroom, the Case of the Teenage Girl
    https://www.youtube.com/watch?v=6Dd6_TghcE0

    This is the sad tragedy of the teenage girl, Madison Coe, who passed away while using her mobile phone in the bathroom. I hope her story provides awareness around the dangers of using electronics in the bathroom.

    Reply
  22. Tomi Engdahl says:

    When is dual fusing in power supplies really dangerous?
    http://www.electropages.com/2017/08/when-is-dual-fusing-in-power-supplies-dangerous/?utm_campaign=&utm_source=newsletter&utm_medium=email&utm_term=article&utm_content=When+is+dual+fusing+in+power+supplies+really+dangerous%3F

    Many AC-DC electronic power supplies are now certified to meet the ITE (Information Technology Equipment) IEC 60950-1 standard and also the medical IEC 60601-1 standard. These supplies often have two internal fuses, one in the Line and one in the Neutral connection. This is to guarantee protection in a medical application where the polarity of the Line and Neutral could be interchanged due to an outlet socket or line cord wiring error.

    If an electrical or electronic device consumes enough power to exceed the AC socket rating, it would need to be directly connected to the building wiring, or be permanently connected. In this case, polarity reversal is not possible. The NEC, CEC, IEE Wiring Regulations and IEC 364 though, specifically prohibit fusing the neutral in this type of equipment.

    When considering a power supply for this type of application, choosing a dual fuse power supply may cause an issue. One option is to select a single fuse product, or contact the manufacturer to have the Neutral fuse bypassed as a modified standard – although in this case the safety certifications may need updating.

    Reply
  23. Tomi Engdahl says:

    Tukes: The arches caused two deaths this year in Finland

    This year, two fatal electric accidents have occurred in the vicinity of the overhead lines. The Safety and Chemicals Agency (Tukes) reminds that electric shock is not always even needed to touch, as electric jumps over the air gap over the air line, for example, a work machine or a crane.

    The danger caused by the overhead lines should be taken into account in the safety planning of the site and in the vicinity of the air lines.

    One of the accidents was caused by the driver of the suction truck lifting the car’s tank under the high voltage line to dislodge the sandload in the car. In this case, the car’s tank caused an arc and therefore a powerful electric shock to the driver. The driver was delivered to an ambulance at a hospital where he later died.

    Another accident occurred at the element factory’s warehouse. Two men were lifting elements near the air lines.

    - It’s important to understand that an electric shock can get, even if it does not even touch the air ducts. Therefore, even in workplace safety planning and in the vicinity of the overhead lines, account must be taken of the risk of electric arc and electric shock, remembers Senior Officer Leila Öhman Tukes.

    Source: http://www.etn.fi/index.php/13-news/6860-tukes-valokaaret-aiheuttaneet-kaksi-kuolemaa-taenae-vuonna

    More:
    http://www.tukes.fi/fi/Toimialat/Sahko-ja-hissit/Sahkolaitteistot/Turvallisuus-sahkojohtojen-laheisyydessa/Turvallisuusohjeita/
    http://www.tukes.fi/fi/Toimialat/Sahko-ja-hissit/Sahkolaitteistot/Turvallisuus-sahkojohtojen-laheisyydessa/
    http://www.tukes.fi/Tiedostot/sahko_ja_hissit/Hengenvaara_esite.pdf

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