What’s the ‘safe distance’ for Arc Flash risks?

What’s the ‘safe distance’ for Arc Flash risks?

Given the nature of the injuries that can be sustained in an Arc Flash, the general lack of awareness of Arc Flash risks is still disappointingly low.

Our Arc Flash Survey in 2017 revealed a staggering 78% of respondents were still unaware of what the Health & Safety Executive’s (HSE) guidance included when it came to reducing the risks of Arc Flash incidents.

In the UK, British Standard BS EN 50110, Operation of Electrical Systems, provides the governing safety guidance for people working in an environment that exposes them to the hazards of an electrical arc; the specifier should select this where a risk assessment has identified an Arc Flash risk.

Within all UK safety guidance, the overriding directive is to eliminate risk wherever possible. But it’s sometimes essential to work within a live power environment.

In these cases, defining the Arc Flash protection boundary through a Flash Study sets the minimum ‘safe’ distance from any live equipment which poses a risk.

It determines exactly how far away a someone who’s unprotected would need to be to avoid being exposed to an Arc Flash with an incident energy of 1.2 cal/cm2 for a tenth of a second.

The risk associated with being any nearer to such an Arc Flash event is likely to result in second degree burns, so this distance from the equipment becomes the Arc Flash Protection Boundary.

Boundaries for arc flash incidents

Shock hazard boundaries are more common and work on a fundamentally similar principle. The distances set by shock hazard assessments include a Prohibited Boundary, Restricted Boundary and Limited Approach Boundary.

Generally, unqualified personnel can cross into the Limited Approach Boundary provided they have the appropriate PPE and are strictly supervised by someone with the appropriate training.

However, because of the nature and severity of an Arc Flash incident, the safe distance set out in the Arc Flash protection boundary overrides shock hazard boundaries.

So, if the Arc Flash protection boundary extends beyond the Limited Approach shock hazard boundary, only trained and qualified workers with appropriately Cal rated Arc Flash safety clothing and equipment can enter this zone where their work is both essential and approved.

Here at ProGARM, we provide a last line of defence against an Arc Flash in the form of specialist, industry leading PPE. But there’s no substitute for awareness and proactive steps to minimise the risks of Arc Flash incidents occurring in the first place.

For more information about Arc Flash protective clothing, please contact us on +44 (0) 1482 679 600 and speak to one of our sector specialists.