Electrical Safety

Electrical Hazards: 

•  B-Burn. 
•  E- Electrocution. 
•  S-Shock. 
•  Arching. 
•  F- Fire.
•  E-Explosion

                                                                                                                              

• According to HSE legislations high voltage is defined as voltage exceeding 1000V (AC) and 1500V (DC)
• High Voltage transformers should be protected by 2.4 m (8 feet) high fence. 

Electrical Protection Devices: 

Various protective systems can be used for electrical equipment, such as:  

• Fuses - a weak link in the circuit. 
• Earthling - a low-resistance path to earth for fault current. 
• Isolation - cutting the power.  
• Double insulation -separating people from the conductors using two layers of  insulation . 
• Residual Current Devices (RCDs) - sensitive and fast-acting trips.  
• Reduced and low voltage-so that less current flows during an electric shock accident. 

Electric Shock: 

Instructions for the treatment of persons suffering from electric shock shall be prominently displayed in all switch rooms, workshops etc.where electric equipment is located. All personal, who are exposed to the possibility of electric shock, shall be trained in emergency procedures, with regard to treatment of electric shock victims. 

Factors of Severity of the Effect of Electric Shock: 

1. The level of voltage, 

2. The amount of body resistance of current flow, 

3. The path the current taken through your body, 

4. The length of time of current flow through your body. 

Electrical Fires and Explosions Causes 

• Electrical equipment may be faulty and overheat as a result, leading to a fire.  
• The system may be overloaded; as too much current passes through,it overheats,causing overheats,causing fire or explosion.  
• Overheating during charging. Many portable or mobile devices can become hot during the charging process. This is particularly the case if the equipment is faulty or of poor quality (e.g. counterfeit mobile phone batteries and  chargers). 

•  Equipment may be misused (e.g. it may be connected into the mains supply by pushing bare wires into thesocket rather than using the proper plug).

•  A flammable atmosphere may be present which electricity . This can happen in two different sets of circumstances: 

• The wrong type of electrical equipment is brought into an already known existing flammable atmosphere.  
• A flammable atmosphere is accidentally created in an area where it would not be expected (e.g. due to spillage).   

• Electrical equipment may produce heat or sparks as part of its normal operation (e.g. a fan heater gets hot during use).If it is poorly positioned next to a full waste paper bin, it may start a fire.

• One common cause of overheating electrical equipment is poor internal connections. When two electrical components are joined together, the connection between them must be well made and secure 

Arcing: Arcing is where electricity jumps across an air gap. 

The main risks associated with arcing are: 

• Electric shock as a result of being struck by the arc. 
• Direct burns as a result of being struck by the arc. 
• Indirect burns from the radiant heat given off by the arc and from the melting of any equipment struck. 
• Damage to the eye as a result of the ultraviolet (UV) light that is emitted by the arc. 

Safety precautions for electricity: 

1. Suitable electrical equipment should be  selected for the purpose. 

2. Power should be isolated before working on electricity and lock-out tag-out procedure should be followed. 

3. Electrical works should be restricted to the competent workers only. 

4. All electrical installations, equipment and appliances should be subject to user checks, formal visual inspections and testing.

5. Electrical equipment should not be used in wet condition. 

6. Various protective systems should be used such as fuses, RCB, ELCB, GFCI, earthing etc. 

7. Non-conductive tools to be used while working with electricity. 

8. Work permit system should be followed. 

9. Workers should wear appropriate PPEs such as electric shock proof gloves, boots etc. 

Control: 

1. Selecting Right Tool for the Job 

2. Fuses and Miniature Circuit Breakers 

3. Earthing 

4. Residual Current Devices 

5. Reduced and Low-Voltage Systems 

6. Isolation of Supply 

7. Competent Person 

8. SSOW 

9. Double Insulation 

Selecting Right Tool for the Job

Electrical equipment must be carefully selected to ensure that it is suitable for the: 

• Electrical system that it will become a part of (No electrical equipment should be put into use where its electrical strength and capability may be exceeded and give rise to danger)

• Task that it will perform; (Select right tool for the job) 
• Environment in which it will be used (Weather, Natural hazards, Extremes of temperature and pressure, Dirty conditions, Corrosive conditions, Liquids and vapors, Flammable substances) 
  Fuses and Miniature Circuit Breakers 
  A fuse is a device used to prevent current overload.

Advantages: – Are very cheap and reliable. – Offer a good level of protection for the electrical equipment against current overload. 

Limitations: – A fuse does not stop current flow quickly enough to prevent – Are very easy to bypass 

• Miniature Circuit Breakers (MCBs) are electromechanical devices that work in a similar way to fuses to protect equipment from current overload (i.e. they provide overcurrent protection).One significant difference is that a MCB does not melt in response to current overload; it simply trips out and can be reset by pressing a button. This gives one of the main advantages of MCBs – they do not have to be removed in order to be reset and so they are more tamper proof than fuses. The limitations of MCBs are similar to those for Fuses.

Types of Earth Leakage Circuit Breaker (ELCB) 

There are two types of Earth Leakage Circuit Breaker (ELCB) 

•  Voltage Operated ELCB 
•  Current Operated ELCB 

How to Check Earth Leakage Circuit Breaker 

Earth leakage circuit breaker must be check once a year to whether that is working properly or not. Usually, the circuit breakers are in the ON position. Here we have listed the step by step process for how to test the earth leakage circuit breaker.

• If the ELCBs are not working properly, then we should contact sales otherwise service engineers nearby us. 
• To deactivate the breaker, just push the operation switch, so that the power supply turns off. 
• Press the test button of the earth leakage circuit breaker by using a pointed object or a ballpoint pen.
• verify that the ELCB goes to the OFF position. 
• Revisit the ELB to the ON position. 
• Switch ON the main power. 

Earthing 

Earthing is a way of protecting equipment so that, in the event of an electrical fault, current flows safely to earth rather than flowing through a person who might be touching the equipment. 

•  The earth wire of an item of electrical equipment is usually connected to the outer metal casing or chassis of the equipment. Electricity always takes the path of least resistance, and since the earth wire will have very low resistance, the majority of fault current will flow safely to earth through the wire. Any person touching the casing will receive a minor shock. 
• The color code for earthing wire is Yellow and Green.

Advantages: –Protects the person from fatal electric shock.–Often provides secondary protection to the equipment because a large fault current flowing to earth will overrate and trip the fuse or MCB.

Limitations:– A poor or broken earth connection will prevent the earth from working properly;since the earth wire does not take part in the normal functioning of the equipment, this fault can go completely undetected-It is easy to disconnect and disable.  

Use of Safe Systems of Work 

This SSW is likely to make use of the following controls: 

•  Permit-to-work system. 
• Competent persons. 
•  Insulating PPE(such as gauntlets and boots). 
• Insulated tools and equipment (such as screwdrivers). 
• Designated work areas (such as ‘earth-free zones’). 

Double Insulation 

Double insulation(or Class II equipment)is  that there are two layers of insulation between any potentially live conducting 

surface that the user might touch (such as the metal casing of the equipment) and any live conductors, or the equipment has a non-conducting plastic casing. 

Advantage:Double insulation is that it relies on insulation rather than the electrical system itself for safety. 

Limitation: Insulation must be routinely visually inspected because there is no earth protection. 

• A commonly used device for detecting the location of buried cables is the Cable Avoidance Tool (‘CAT scanner’). 

Types of Electricity:

1. Static electricity. 

2. Dynamic electricity 

Static Electricity:

Electricity which is produces by friction of two non-conducting substances. Static Electricity means electricity at rest,it can be transferred from one place to another and hence of no use at all. 

Dynamic Electricity: 

Electricity which is produces by conservation of energy such as mechanical into electrical, chemical into electrical, thermal in to electrical, etc...It can be transferred from one place to another and can be safely utilised.

Static Electricity Hazards: 

• Four conditions required for explosive ignition. 
• Mechanisms for producing hazardous conditions. 
• Static generation, Accumulation of charge and potential. 

Spark discharge, Flammable vapor. 

Method to Control the Accumulation of Static Electricity: 

• Grounding & Bonding; 
• Humidification of the process area (about 70%); 
• To make material conductive (e.g. belts coated with metals); 
• Discharge method (Static eliminators); 
• Ionizers (Radioactive);and Metallic spiral on pipe lines.

 Emergency Procedures Following an   Electrical Incident 

• Do not touch the casualty. 
• Call for help and an ambulance.  Turn off the power supply. 
• If the power supply cannot be switched off, then carefully push or pull the casualty away from the live part 
• using non-conducting material, such as timber or dry clothing. 
• Check breathing: 
• - If the casualty is breathing, place them in the recovery position. 
• If they are not breathing, apply cardiopulmonary resuscitation. 
• Treat any obvious burns. 
• Treat for physiological shock. 
• Make sure they get professional medical treatment (heart problems and internal burns may not be 

  Inspection and Maintenance of Electrical  Equipment: 

• Third party certification 
• Inspection tag 
• Color coding 
• Guarding system 
• Double insulated 
• Rating 
• Defects in the wiring or cable 
• Visual Inspection 
• CE marking and EU conformity 

LOTO: 

It is a procedure in which dangerous mechanical machineries are properly shut-off and restricts them to self-start 

prior to the maintenance work.  

• Key operated padlocks and Tag shall be used to apply LOTO with numbering 

LOTO Procedure: 

1. Identify the energy source 

2. Inform all the people 

3. Shutdown the equipment  

4. Isolate equipment 

5. LOTO equipment  

6. Release stored Energy 

7. Verify Isolation 

8. Perform Servicing- shutdown work 

9. Release from LOTO 

Types of LOTO: 

• Electrical.     RED 
• Mechanical BLUE 
• Instrumental GREEN  
• Contractor YELLOW  
• Production WHITE 

When LOTO is applied: 

Adjusting, cleaning, lubricating, inspecting, modifying, replacing parts, tool changes 

Exceptions of LOTO: 

1.  Routine, repetitive  

2. Guards/safety not bypassed 

3. No human contact in the point of operation .