Arc Flash Clothing, PPE & Flash Protection Kits
Arc flash clothing and protection equipment including coveralls, gloves, helmets, face shields and general head-to-toe PPE is used to protect against flashover but will not prevent arc flash hazards.
Consequently, PPE should be used as the last line of defence when implementing a documented electrical safety plan for maintenance, repair and diagnostic procedures involving energised LV, MV or HV electrical equipment.
Arc flash clothing and PPE should be worn when working on energised conductors, cables or circuits.
Due to the complexity and criticality of medium/high voltage electrical systems it can be impossible to switch off, secure isolation, work dead and never work on live equipment. If LV, MV or HV equipment cannot be de-energised and therefore live-working is unavoidable, electrical workers must be qualified, trained and wearing appropriate personal protective equipment (PPE).
According to the UK HSE (Document HSG85) work on or near live exposed conductors should “rarely be permitted” and if a permit-to-work is allowed 3 conditions should be satisfied:
- it is unreasonable for the electrical conductor to be dead
- it is reasonable for the person to be at work on or near that electrical conductor while it is live
- suitable precautions (including, personal protective equipment PPE) have been taken to prevent injury.
CATU Electrical ranges of arc flash clothing and switching suits include convenient kit form PPE with face shields, helmets and visors to protect the head/face and gloves for hand protection of utility workers – worn by substation engineers, SAP’s, cable jointers and overhead linesmen.
T&D also distribute the ProGARM range of Arc Flash Clothing and Flame Resistant protective garments for every-day wear and protection – the highly breathable clothing ranges are designed for comfort and safety without compromising the ability of the wearer to work productively, safely and unhampered by cumbersome garments prone to overheating.
Contact us to discuss how to minimise and mitigate arc flash risk using correct clothing and PPE.
What Is An Arc Flash?
Arc flash is a short circuit where the electrical current arcs across an air gap.
Flashover occurs when an electrical discharge travels through the air and releases an intense and explosive burst of energy – the flash is capable of causing serious harm or fatal injury therefore appropriate clothing and protection must be worn when carrying out electrical maintenance tasks which could release an arc flash.
4 dangers to the worker i) thermal ii) light iii) sound iv) pressure
Over 50% of workplace accidents from low voltage switchgear are from arc related faults – they are not confined to medium/high voltage power distribution networks where even small levels of residual voltage can trigger an arc flash.
Generally, an arc flash results from either a phase to ground or a phase to phase fault during following activities:
- Phasing Operations – especially MV-HV systems at 11kV, 33kV, 66kV, 132kV+
- High Impedance Faults – Hi-Z arcing on overhead, substation and distribution feeders
- MV HV Switchgear – opening/closing breakers and fused switches
- Fusegear – changing fuses on LV distribution, street lighting and service feeder pillars
- DC Battery Storage – opening doors/covers on systems during maintenance
- Circuit Breakers – power racking is HRC4 task with arc rated clothing rated at 40 calories/cm2
- Live Cables – excavation, fault finding, jointing near exposed LV and 11kV-33kV conductors
- Jointing Cables – working in trench, substation and on link-boxes
- 33kV Substations – testing and survey of cable terminations, RMU, transformers
- High Voltage Flashovers – opening high voltage switchgear, cable boxes, cabinets and panels without following correct isolation procedures or obtaining necessary authorisation permits
Arc flash clothing is typically used when working on switchboards, panelboards, industrial control panels and motor control centres at low, medium or high voltages.
Arc flash calculators should be used to analyze site specific hazards and structure an electrical safety procedure to reduce the effects of arc flashover – adequate levels of protection and clothing for working on energised electrical power systems including LV, MV and HV should be implemented to include PPE suitable for direct contact with the live electrical equipment to be worked upon.
Arc flash causes serious injuries to face, hands and body – shown here is an ultra slow motion reconstruction of a 480v blast:
Explanation Of Arc Flash Risk Levels – NFPA 70E
The National Fire Protection Association (NFPA) in the USA introduced NFPA 70E “Standard for Electrical Safety in the Workplace” to reduce the number of arc flash related workplace accidents. NFPA 70E provides clear guidance on Personal Protective Equipment (PPE) selection to reduce and avoid injury in the event of an incident.
NFPA 70E-2012, the Standard for Electrical Safety in the Workplace, is the primary industry consensus standard in the USA that addresses arc flash safety – NFPA 70E contains extensive information on safe work practices, analysis procedures, requirements for documentation and PPE selection principles intended to allow for workers to be appropriately protected against arc hazards.
NFPA has identified 4 hazardous risk category (HRC) levels which is used to select the correct level of arc rating for protecting clothing and PPE – the severity danger according to HRC is the level of arc flash protection clothing that must be worn to protect against a minimum level of incident energy measured in calories/cm² as the table below.
PPE used should match the calculated level of risk to ensure adequate worker protection.
|Incident Energy Level
(cal / cm2)
|PPE Protection Type||Arc Flash PPE Protection Details (Basic Examples)|
|0 – 1.2||0||0||1 layer untreated cotton (covering all body), polycarbonate safety spectacles, lightweight cotton gloves|
|1.21 – 4||1||1||Cotton undergarments, 1-layer flame retardant (FR) work wear, helmet, polycarbonate safety spectacles, lightweight FR gloves|
|4.1 – 8||2||2||As above but with 2 layer FR outer work wear that has wrist closures, and a full face polycarbonate face shield/visor. A FR single-layer balaclava may also be worn to protect the face|
|8.1 – 25||3||3||3 layer FR outer work wear with cotton under garments and FR shirt, a full-face hood or visor with safety spectacles underneath, chrome leather gauntlets|
|25.1 – 40||4||4||Typically 4 layer FR outer work wear, FR and electrically insulated footwear and suitable FR material spats to close off the ankle area, FR gloves or chrome leather gauntlets, a hood constructed from a triple layer of FR material with a sewn-in polycarbonate face shield with a minimum of 2 panels of suitable thickness with one coated with a gold film for UV protection.|
3 Common Causes Of Arc Flash
- Human Error & Carelessness – unsafe, ambiguous work procedures, maintenance mistakes, mishandling conductive tools, cables and metal covers; overall absence of authorised procedures to carry out unfamiliar tasks on critical, high-risk electrical equipment
- Negligent Preventive Maintenance – not checking for loose terminations, allowing conductive soot, dust and debris build-up critical in medium/high voltage networks. High resistance ground faults and not testing stored energy (e.g. spring-operated pressure switches)
- Improper Electrical Equipment Sytems – incorrect modifications or using legacy equipment which is non-conformant with modern arc flash standards, such as open-type switchboards and fuseboards
Effects Of Arc Flash
- Body Burns – heat energy from a single arc flash can reach 35,000°C, serious thermal burns with destruction to skin and tissue
- Blast Injury – creates a fatal explosive pressure wave of energy and propulsion forces up to 2000 pounds per square foot
- Lung Damage – release of poisonous gases and exposes victims to inhalation of molten debris and droplets
- Hearing Loss – arc blast causes extreme high sound levels, resulting in potential hearing damage, ruptured ear drums
- Eyesight Damage – intense light from the flash may cause temporary or permanent blindness
♦ Further reading
- Keeping Electrical Switchgear Safe HSG230
- Maintenance Of Electrical Switchgear & Controlgear For Voltages Above 1kV (Up to 33kV-36kV)
- Avoiding Danger From Overhead Power Lines General Guidance Note GS6
- IEC 61482-1-2:2014 Live Working – Protective Clothing Against The Thermal Hazards Of An Electric Arc – Part 1-2: Test Methods – Method 2: Determination Of Arc Protection Class Of Material & Cothing Using Constrained & Directed Arc (Box Test)
➡ View the complete range of Arc Flash Protection Equipment & Clothing.
Arc Flash Protection ♦ Switching Suits ♦ Substations LV MV HV ♦ Clothing ♦ PPE ♦ Jackets ♦ Helmets ♦ Gloves CATU Electrical Safety