Arc Safety: No Flash in the Pan
Arc Safety: No Flash in the Pan
A short causing an arc flash within an electrical device produces light and heat, leading to potentially fatal burns and other serious injuries. ROWAN WATT-PRINGLE takes a look at some of the latest personal protective equipment (PPE) available to those at risk from these deadly electrical faults.
An arc fault occurs when an electrical connection is formed through the air, either to the ground or between separate voltage phases in an electrical system. This produces an arc flash, which can generate searing temperatures of almost 20 000°C (more than three times greater than the sun’s surface temperature) and produce dangerous levels of radiation. When this happens within an enclosed environment like a transformer box or electrical switchboard, the force of the discharge is magnified even further, emitting a concussive pressure shockwave and blasting out molten metal and other debris. “Arc flashes are extremely dangerous and blasts can affect people as far as seven metres away,” notes JW Eggink, technical sales specialist for thermal protection at integrated workplace safety solutions provider, BBF Safety Group (BBF).
Using the correct PPE is vital to prevent serious burns from these potentially fatal faults. The type of equipment needed varies according to voltage level involved in a specific electrical task and ranges from protective helmets and visors, hearing protection, gloves, boots and overalls to flame resistant (FR) full-body arc flash suits and undergarments. Lyndall Farrer, marketing manager for leading PPE manufacturer and supplier Dromex, says that the Dromex Arc Range is designed to protect against all thermal hazards associated with an arc flash, stating, “we always recommend the use of a full head-to-toe arc protection solution to offer safety in any eventuality”.
Eggink believes that many companies and electrical contractors don’t necessarily realise the importance of wearing the right protective garments, explaining, “The shorter a person’s exposure to an arc flash, the better their chances of survival and lessening the severity of injuries, which is why the garments must have the ability to self-extinguish as quickly as possible.”
The standard for arc rated garments is that they can self-extinguish within two seconds of flame exposure being removed, but Eggink says this is usually tested on unused garments under laboratory conditions. An important consideration is that many chemically treated FR fabrics have been shown to fail (and completely burn out) after as few as 15 washes with an everyday household detergent. “Probably the scariest factor about this is that treated fabrics showed no noticeable signs of deterioration prior to failing,” says Eggink. “Wearers may believe they are still protected against potential burns, when in fact the FR-treated garments have lost their protective abilities.”
One way to counteract this is to use fabrics with inherent FR qualities, like Beier’s I-Arc fabric that is used to make BBF’s Bova brand of durable PPE. “The major benefit of these fabrics is that as long as the garment is visually intact, the wearer is protected: the FR quality does not wash or wear away,” Eggink points out.
Farrer agrees, noting that the distinctively engineered, inherently FR fabric used in Dromex’s Arc Protection Technologies fabric (A.P.T.) has not only passed the National Fire Protection Association’s (NFPA’s) “100 wash test”, but also tests at 200 washes. “We believe in uncompromising safety. Our fabric is certified to the highest local and international standards and has passed ‘Red Metal’ testing, offering additional bodily protection from molten metal, vaporised copper and metal oxides up to 1400°C,” she says. “This offers the wearer effective protection and peace of mind – molten metal is a deadly hazard during an arc flash incident and can penetrate other synthetic lightweight fabrics.”
Another recent development is the introduction of Dromex’s specialised arc helmet and visors. “This essential head and face protection, featuring leading Real View Technology, has been tested to EN166 standards against molten metals and hot solids. This enhances safety by replacing green or amber face shields, ensuring the wearer can accurately identify the colour of the wires they’re working with,” says Farrer.
PPE provides protection after an arc flash incident has occurred and should therefore be viewed as the last (although essential) line of protection. Reducing the frequency and severity of incidents can be achieved through a complete arc flash hazard assessment and the application of technology such as high-resistance grounding, which has been proven to reduce the frequency and severity of incidents. “We always advocate a thorough energy/incident analysis and calculation conducted by a qualified professional. Thereafter, we recommend the appropriate PPE and workwear based on the hazard,” Farrer concludes.