When there’s a high concentration of flammable gases, vapours or dusts in an area, it turns a routine job into a risky and complex endeavour. Callum Fitzpatrick takes a look at installations in hazardous areas.

Entering a hazardous environment is always a challenge for electricians. Not only do you have to be incredibly cautious to ensure the safety of yourself and those around you, but every stage of an installation has its own rules, regulations and Standards which need to be adhered to.

As it is quite a broad term, there is often some confusion as to what is classifi ed as a ‘hazardous area’. Simply put, it is any environment that is considered especially unsafe due to the presence of fl ammable and/or explosive substances. Because electrical equipment transmits a level of energy in some form, if this energy is not harnessed correctly, it may become a source of ignition for the gas, vapour, or dust in the environment – which can cause potentially catastrophic results.

EXPLOSIVE ENVIRONMENT

Understandably, stringent safety measures need to be implemented both before, and while, an installation takes place in any type of hazardous area.

Schneider Electric recommends that before entering a site, you need to make sure that the operator of the electrical distribution system has a ‘Safe System of Work’ in place – a set of safety rules governing how equipment is made safe to work on, and how it is then returned to service. This usually includes the issuing of a specific ‘Permit to Work’ to the contractor, ensuring that the specific hazards are addressed prior to any work commencing in the area.

If there is a hazard present, it needs to be specifically addressed in the safety plan. And if this danger is irremovable, then measures need to be taken to prevent a source of ignition during the work. A zone classification of the area is used to understand the level of ignition energy required to cause combustion – and therefore to be avoided (Tables 1 and 2.)

Once it is established that no work activity can cause accidental ignition, it needs to be ensured that no work is carried out at a time when a circuit or apparatus is energised.

Additionally, Schneider recommends that you identify the point of electrical supply and ability to reach it quickly, with work only being carried out in the presence of a safety observer who is competent in the specifics of the workplace.

When the project is completed, it is essential that any equipment that was worked upon is still fit for purpose. For example, replacing a light globe in a hazardous area requires that the covers have been re-fitted correctly – ensuring that gaps in the enclosure remain in accordance with the manufacturer’s design specification, so any spark within the equipment (e.g. a simple light switch or light fitting) cannot release sufficient energy to cause ignition. Too small a gap and an explosion could occur within the equipment, too large a gap and the equipment could ignite the hazardous area.

PRODUCT CERTIFICATION

When it comes to choosing products for an installation, individual risk assessments and a safe work method statement should be completed by specialists in these areas before decisions on applicable products can be made.

Further, there are several schemes in place to guarantee that a product is suitable for a hazardous application.

There are also several standards and certifications in place which provide assurance that a product is fit for purpose.

AS/NZS 2381 Electrical equipment for explosive gas atmospheres stipulates that all equipment used in hazardous areas must be certified with IEC Ex, AUS Ex or ANZEx.

IECEx is a global certification scheme based on standards of the International Electrotechnical Commission (IEC). It caters for differing countries whose national standards are either identical to those of the IEC or else very close to IEC standards.

The objective of the IECEx system is to facilitate international trade in equipment and services for use in explosive atmospheres, while maintaining the required level of safety. This aims to reduce testing and certification costs to the manufacturer, and reduce the time it takes for the product to reach market.

The ANZEx Scheme is an Australian and New Zealand scheme similar to IECEx. Compliance is established through testing of equipment and auditing of a product quality plan, with visits to the manufacturer’s premises. The AUS Ex scheme is an Australian certification scheme for explosion-protected electrical equipment. Applications for the scheme finished in 2003 and are no longer accepted, however, a past certification is still valid if it hasn’t expired.

Another scheme is ATEX – A European standard for equipment and protective systems intended for use in potentially explosive atmospheres. However, ATEX is a manufacturer self-certification scheme and does not satisfy Australian Standards nor does it meet obligations established in the electrical safety laws. If supplied equipment is only ATEX-certified, a written assessment from a suitably qualified person is needed; indicating whether the standard the equipment was manufactured to aligns with equivalents demanded by Australian Standards.

THE BURNING ISSUE

As well as an electrical spark, hot surfaces can inevitably cause the ignition of gases, vapours and dusts.

Marechal Australia general manager Georg Turin says that, “it is necessary to ensure the maximum surface temperature of equipment introduced into a hazardous environment does not exceed the ignition temperature of the gas, vapour or dust that may be present in the environment.”

Consequently the substance grouping and associated maximum temperature classifications shown in Table 3 have been established.

INSTALLERS

Because of the inherent complicated dangers in a hazardous environment, Georg says that an installation should not be carried out by domestic electricians.

“Installations of suitable electrical equipment in hazardous environments are only suitable for certified electricians and not for general environment electricians,” he says.

“There are relevant qualifications and certifications you need to obtain before undertaking an installation of this nature, additionally, you need to obtain authorisations from plant management for plant shut-down time and duration, as well as required plant and process shut-down and start-up procedures.

“It should be mentioned that in different areas, electricians will – depending upon the plant origin/ownership – be required to work to Australian, IEC, CSA or UL Standards.

“After completing an installation, proper authorised personnel need to approve the performed work prior to re-energising commencing the start-up of a plant.”