Can Arc Flash Clothing Save Utility Workers Lives?
Published 17 Nov 2017
Yes. Here is the evidence.
by Chris Dodds T&D - estimated reading time 5 minutes
Utility Workers & The Risk Of Arc Flash
Utility workers stand in the frontline of electrocution and arc flash risk – facing daily hazard whether in the cable trench, joint bay, substation or working in front of switchboard panels.
Jointers, Linesmen, SAP’s and Civil Engineers should all be protected against the working dangers of arc flash – according to the UK Health & Safety Executive workers engaged in the location, identification and excavation of of buried services should be ensure adequate protective clothing is used when working around underground cables:
Injuries to workers are typically caused by the explosive effects of arcing current, also known as arc flash, and by the associated fire or flames that can result when a live cable is penetrated by digging tools (typically “shovels and spades”) – the risk is elevated where medium/high voltage cables are trenched and backfilled but not protected using 11kV/33kV cable covers.
Arc flash can also occur when a cable is crushed severely enough to cause internal contact between the cable conductors, or metallic cable sheathing and one or more conductors.
Injuries are severe – potentially fatal – burns to the hands, face and body: electric shock is possible but less likely.
Incidents can also arise from cables, connections and cable terminations which have been damaged but left unreported and unrepaired, or which have deteriorated with age.
Here utility workers are shown live-line working from an aerial lift on overhead conductors from the bucket truck.
Arc Flash – The Evidence
Pictured below are ProGARM arc flash polo shirts post-arc blast impact.
Clearly the garment has quelled the arc flash due to the inherent flame retardancy of the clothing fabric. The cause of the arc flash was triggered by an LV jointer using a Jack Hammer in the vicinity of an underground low voltage cable.
The strike to the 3 phase 120sqmm CNE utility cable caused an arc flash which if not protected against using appropriately rated clothing would have inflicted serious skin injury and burns to the cable jointers chest and arms.
Typical risks include: fuse replacement and maintenance on feeder pillars and link boxes, live cable jointing, underground cable excavation and switching operations in substations at low, medium and high voltages.
As well as correctly specified levels of arc flash clothing protection utility workers should ensure appropriate levels of protection against electrical shock hazard by wearing suitable insulating gloves, arc flash gloves and insulating boots according to the voltage and risk.
Cable Strikes & Arc Flash Risk
Failure to implement and follow the HSG47 Guidelines can cause fatal injury to workers striking buried electricity cables operating at LV MV HV – workers have been electrocuted and engulfed in flames coming into accidental contact with 11,000 volt (11kV) underground cable where sites have not been scanned for live buried cables by cable avoidance tools.
Cable strike incidents can be avoided when work is properly planned and supervised in accordance with HSG47.
The photographs are compelling evidence of the electrical safety requirement to protect cable jointers whether working on LV, MV or HV power cables, overhead lines or substations.
The investment in clothing is an investment in worker protection and ultimately life.
Naturally, all ProGARM arc flash clothing is vigorously tested in the laboratory and to witness real life evidence of the protection provided underlines the need to take arc flash seriously.
Mark Lant, an Arc Flash Technical Expert at ProGARM comments: “Obviously, we’d prefer it if Arc Flash incidents never occurred. However, the fact is they do, and we’re pleased to see our arc flash polo shirt performing as effectively in the field as it did in the lab. We wish the cable jointer a speedy recovery from his other injuries.”
Arc Flash Clothing & Electrical Safety Tests
Arc flash clothing and garments are tested to European norms and standards:
- EN ISO 11612: 2008 (A1 B1, C1) – ISO 11612:2008 Protective Clothing – Clothing to protect against heat and flame
- EN1149-5: 2008 Pt 5: 2008, Pt 3: 2004 (Charge Decay) – Protective Clothing – Electrostatic Properties
- EN ISO 20471: 2013 Classs 3 – High Visibility Clothing – Test Methods & Requirements
- IEC 61482-2: 2009 Class 1 – Clothing Protection For Thermal Hazards Of An Electric Arc
Can An Arc Flash Occur While Ground Digging?
1. On average 8-10 cable strikes are reported in the UK every day
2. Over 90% of LV-HV underground cables in the UK are unmarked
3. Over 1,000 electrical incidents reported to the HSE in the UK every year
4. 25 of these are fatalities (HSE)
5. Fines can be an excess of £2 million
Arc Flash Learning & Resources
We can help – should you require arc flash calculators or advice on the type of clothing and protection available please do not hesitate to contact us.
Thorne & Derrick are specialist distributors of LV, MV & HV Cable Installation, Jointing, Substation & Electrical Safety Equipment:
- LV Cable Joints & Termination – Cold Shrink & Heat Shrink
- MV HV Cable Joints, Terminations & Connectors 11kV 33kV
- ProGARM Arc Flash Clothing & Protection – Brochure Size: 8.77 MB
- UK HSE HSG47 Avoiding Danger From Underground Services Size: 1.15 MB