A guide to hazardous area equipment published on the HSE website this month gives an illustration of how the COMAH Competent Authority approaches the inspection of such zones.

The Inspection of Electrical, Control and Instrumentation Systems at COMAH Establishments Operational Delivery Guide is aimed at encouraging “proportionate action to control a given hazard”.

In some instances, this is in addition to other potential hazards – for example, the specific risks posed by a nuclear installation.

But at times it is simply about using hazardous area equipment safely, and preparing for risks such as releases of electrical energy, electrical sources of ignition, and safety systems like trips and alarms.

“Failure to control process conditions and the risks from electrical installations and equipment have been the main or underlying cause in many major accidents both in the UK and abroad, including Buncefield and BP Texas City,” the document adds.

In terms of explosive atmospheres – one of three priorities identified in the document – a shortlist of possible sources of ignition is provided.

This includes electrical and instrumentation equipment, lightning, static, radio frequency radiation, cathodic protection, and the mitigation of releases using flammable and toxic gas detection and fire detection.