The 5 Safety Rules of Electrical Engineering

IEC 60479-1 is a standard that provides guidance on the effects of electric shock on the human body. It specifies the basic principles and safety rules for the protection of persons against electric shock.

Some of the key points of IEC 60479-1 include:

1. Limiting the duration and intensity of electric current flowing through the human body to avoid harmful effects.
2. Using protective measures such as insulation, barriers, and distance to prevent or reduce the risk of electric shock.
3. Providing appropriate warning signs and labeling to identify hazardous areas and equipment.
4. Establishing clear procedures for safe work practices, including maintenance, testing, and operation of electrical equipment.
5. Ensuring that personnel who work with or around electrical equipment are properly trained and qualified to perform their tasks safely.
6. Providing adequate personal protective equipment, such as gloves and shoes, for personnel working with electrical equipment.
7. Conducting regular risk assessments to identify potential hazards and implementing appropriate control measures to mitigate the risks.
8. Ensuring that electrical equipment is properly designed, installed, and maintained to minimize the risk of electric shock.

These safety guidelines are designed to help prevent electric shock and protect workers from electrical hazards. Following these guidelines can help ensure a safe and healthy work environment for everyone involved in working with or around electrical equipment.

The 5 safety rules of electrical engineering are crucial safety guidelines based on the IEC 61439-1 standard. Their primary objective is to prevent accidents and injuries when working with electrical equipment, which is essential for anyone involved in electrical work.

By adhering to these 5 safety rules, individuals can minimize the risk of electric shock and ensure a safe working environment. It is imperative to follow these guidelines to protect oneself and others and prevent any unwanted incidents from occurring.

Control cabinet with main switch

The first and foremost rule among the 5 safety rules of electrical engineering is to disconnect. It is crucial to disconnect all parts of the system that require maintenance or repair from all possible power sources. Disconnecting must always be performed on all poles and is typically done at the overcurrent protection device. For circuit breakers, the lever should be flipped downwards, and for fuse holders, the fuse cartridge should be removed, taking care to avoid touching any active parts at the foot contact point when the screw cap is removed.

It is vital to be aware of potential backfeed voltages during disconnection. Therefore, it is recommended to identify all possible sources that could cause backfeed voltages before disconnecting power.

• Turn off/disconnect circuit breakers
• Lock disconnect switches
• Disconnect contactors
• Remove fuse elements

• Possible backfeed voltage
• Special characteristics of the wiring system

• Use personal protective equipment (PPE)
• If several people are required to shut off a system, confirmation must be given verbally or in writing.

Locked out magnetic starter

To prevent an electrical system from accidentally being re-energized and remain under voltage while being worked on, all switching devices used to activate a part of the system must be secured against re-energizing. This can be done by locking the actuating mechanism (Lockout). Lockable main switches, such as those with padlocks, provide safe protection against incorrect, thoughtless, or unintentional switching actions by employees.

It is best to take removable fuses with you and insert a locking dummy element instead.

Lockout tags

It is best to take removable fuses with you and insert a locking dummy element instead. Before starting work, warning tags must be securely attached to warn against unauthorized switching actions (Tagout). These tags should be made of insulating material and attached in such a way that they cannot fall off. For smaller-sized switching devices, stickers, magnetic signs, or plug-in cards with appropriate wording can also be used. If a part of the system can be switched on from two sides, such as ring networks, prohibition signs must be attached to both switches before work begins.

The tag used in the tagout procedure should contain information about the equipment being serviced, the reason for the tagout, the name of the person performing the work, and the date and time the tag was attached. The tag also warns others not to operate the equipment while the tag is in place and explains the potential hazards if the equipment is operated without proper authorization.

• Lockout
• Tagout

• Securely fasten warning tags
• Secure switches with protective covers
• Secure switches/actuators with locking mechanisms

After the first two safety rules of disconnecting and securing against re-energization have been followed, the electrician must verify that the system is truly voltage-free before starting any electrical work. This is essential to ensure that the workers are not exposed to any electrical hazards.

When verifying the voltage-free condition on an electrical installation, it is crucial to check each individual conductor or pole. This task should only be performed by a qualified electrician or an individual who has received appropriate electrical engineering training. Additionally, the verification of voltage absence should be carried out at the workplace or as close to it as possible, and in compliance with the operational instructions.

Benning Duspol® analog plus

Using the correct measuring and testing equipment is critical in ensuring electrical safety. When selecting voltage testers, it is important to choose testers that are specifically designed for the voltage range being tested. Voltage testers with built-in power sources, such as those with optical and acoustic signals, must always have clear and unambiguous displays, even when the power source is running low. It is important to carefully follow the operating instructions, which provide information about possible voltage limits and application restrictions.

Multipurpose measuring instruments are not permitted, as there may be errors in selecting the appropriate measuring range. Portable measuring instruments, however, are not generally prohibited, but they must be suitable exclusively for the respective voltage range and must not be switchable.

Determining the absence of voltage on a Toyota Prius

For installations with a nominal voltage of up to 1000 volts, use two-pole voltage testers according to DIN VDE 0680 to determine the voltage-free condition. These can be devices with a neon lamp and a moving-coil meter, devices with a neon lamp and a moving-iron meter, or devices with LEDs and a function test.

You can tell whether the system is still under voltage by the fact that the neon lamp or the LEDs light up.

Dehn voltage tester PHE4 high voltage

Working on electrical installations with a voltage of over 1000 volts requires special safety precautions to avoid electrical hazards. To determine the voltage-free condition, use a single-pole measuring instrument that complies with DIN VDE 0681. This type of instrument is typically an insulated lance that can be several meters long, and it is manually brought close to the high-voltage conductors.

When using a single-pole measuring instrument, the conductor's voltage status is indicated by optical and acoustic signals. If the conductor is still under voltage, take appropriate safety measures and do not proceed with any work until the voltage is de-energized.

It is important to note that low voltage measuring instruments are prohibited for use on electrical systems with a voltage of over 1000 volts. This is because these instruments are not designed to handle high-voltage currents and can cause electrical hazards if used incorrectly.

Frontmatec Acvoke® Cable Spiker

When working with cables and lines, it can be challenging to determine if there is voltage present at the work site using a voltage tester. However, it is essential to ensure that the cable is voltage-free before performing any work to avoid electrical hazards.

If the disconnected cable can be clearly identified and traced from the switching point to the work site, it is not necessary to confirm that it is voltage-free. However, if the cable's path is not clear, it must be cut at the work site using safety cutters to avoid any potential electrical hazards.

Before determining the voltage-free condition of an electrical installation, it is crucial to ensure that your measuring instrument is functioning correctly. Faulty measurements can be life-threatening and can lead to severe accidents. Additionally, after completing any electrical work, it is essential to inspect the equipment for damage to prevent potential hazards.

Most single-pole voltage testers come equipped with a self-test device that allows you to check important functions without requiring an external voltage source. By using this feature, you can verify that the tester is in good working condition and that it will provide accurate measurements.

• Determine the voltage-free state using a voltage tester, cable spiker device, or cable identification device in a clear (all-pole) manner.

• Operating instructions of the voltage tester
• Does the voltage tester work? (Test it before and after determining the voltage-free state on live parts)
• Is the measuring range suitable for the system?

Dehn grounding and short-circuiting device (partly insulated) for LV cable distributors

Grounding and short-circuiting are crucial safety measures when working on de-energized electrical systems, particularly in medium and high voltage systems. These measures are essential to prevent electrical hazards during maintenance or repair work, especially in overhead lines or low voltage main distributions.

When performing grounding and short-circuiting, the device must be first connected to the grounding system before attaching it to the part of the system to be grounded, unless the grounding switch is used. Additionally, all devices and equipment used for grounding and short-circuiting must be capable of safely connecting to the grounding system and the parts of the system to be grounded and short-circuited, and withstand the expected short-circuit current.

Grounding and short-circuiting is usually done by:

• Fixed grounding switches according to DIN EN 62271-102 (VDE 0671-102), whose task is to ground switched off parts of the system and simultaneously short-circuit in the case of multi-pole grounding switches.
• Forced-guided earthing and short-circuiting devices according to DIN EN 61219 (VDE 0683-200). The use of earthing devices may only be done on de-energized electric system parts that have been checked for voltage-free status.
• Mobile grounding and short-circuiting devices according to DIN EN 61230 (VDE 0683-100).

In low and medium voltage systems (up to 1,000 V), grounding and short-circuiting can be omitted in most cases. However, it is necessary to apply these measures if there is a risk that the system may be energized by a backup power supply system, decentralized generation systems, or overhead lines that are crossed or electrically influenced by other lines.

• With a grounding switch or other devices

• Always connect the grounding point first.
• Ground and short-circuit both sides at interrupt points.
• Ensure that the devices are sized with sufficient cross-section for the expected short-circuit current.

Dehn drape made of EPDM elastomer

When working near live parts, it is crucial to avoid contact as much as possible. However, if de-energizing adjacent components is not possible, it is necessary to cover or fence them off to prevent contact with work materials.

The coverings used must provide sufficient insulation and be able to withstand all expected mechanical stresses. They must also be securely fastened to prevent accidental contact.

Insulating materials such as plates, mats, cover cloths, or protective screens can be used for this purpose. These materials must have sufficient dielectric strength when coming into contact with live parts.

• Cover live parts with insulating cloths, hoses, or fittings.

• Mark danger areas adequately and unambiguously.
• Exercise extra caution.
• All live parts of the system must be covered or fenced off.
• Insulating fittings or rubber mats are only suitable for voltages up to 1000 V.
• If covering or fencing off is not possible, maintain minimum clearances to avoid contact.

• The process of restarting power after completing and checking the work should only commence when no persons, tools, or equipment are left at the workplace.
• The safety measures of the five electrical engineering rules are typically reversed in order. Always disconnect the short-circuit connections first, followed by the ground connections.
• After finishing the work, the person in charge of the facility must be informed about the completion of the work, and the issued release certificates should be returned. The person responsible for the work must inform the person responsible for the facility clearly and unambiguously about the completion of the work, stating the workplace and work group, as well as readiness to turn on the power.

According to the BG ETEM (Employers' Liability Insurance Association for Energy, Textile, Electrical and Media Products), non-compliance with the five safety rules of electrical engineering is a major cause of electrical accidents involving electrical professionals.

From 2015-2019, the BG ETEM registered the following causes of accidents:

• Disconnection: 25.9%
• Lock-out and tag-out: 2.2%
• Voltage testing: 28.2%
• Earthing and short-circuiting: 1.0%
• Covering or fencing off adjacent live parts: 7.9%

These statistics highlight the importance of adhering to the five safety rules of electrical engineering in order to prevent accidents and ensure the safety of all those involved in electrical work.