CompEx Training for Offshore Electricians — Complete Guide

If you work as an electrician on offshore oil and gas platforms, FPSO vessels, or subsea installations in the North Sea or elsewhere, CompEx certification is effectively mandatory. Every major operator — from BP and Shell to Equinor and Harbour Energy — requires CompEx as a condition of electrical work on their installations. Without a current (in-date) CompEx certificate, you will not be permitted to carry out hazardous area electrical work offshore.

Which CompEx Units Do Offshore Electricians Need?

The majority of offshore electrical roles require a combination of installation and inspection units:

Most North Sea platforms have both IIB and IIC areas — IIB for the majority of process and utility systems, and IIC for fuel gas handling, methanol injection, and certain compressor areas. Many offshore electricians therefore hold all four installation and inspection units.

What Makes Offshore Ex Work Different from Onshore?

Offshore hazardous area electrical work presents challenges that are less common onshore:

• Marine environment — constant salt spray, high humidity, and temperature cycling accelerate corrosion of earth tags, armour connections, cable sheath, and enclosure surfaces. Corrosion assessment is a critical offshore inspection skill.
• Vibration — process equipment, compressors, and generators create continuous vibration that loosens cable glands, cover bolts, and terminal connections over time. Missing bolts on Ex d equipment are one of the most common offshore Category X findings.
• Remote logistics — replacement parts may take days or weeks to arrive offshore. Correct deficiency classification is critical: a Category X finding requires immediate shutdown, but a misclassified Category A may create a dangerous delay.
• Simultaneous operations (SIMOPS) — inspection and maintenance often occur while processes are live. Gas testing and formal permit to work procedures are mandatory before opening any Ex equipment.
• Mixed gas groups — the same platform may have IIB areas (propane, methane, hydrogen sulphide) and IIC areas (fuel gas, methanol). Always verify which zone and gas group applies to your specific work location before starting work.

Aberdeen and the North Sea

Aberdeen is the primary hub for UK Continental Shelf (UKCS) offshore electrical workers. The city's workforce serves platforms in the Central North Sea, Northern North Sea, and West of Shetland areas operated by all major UKCS licensees. CompEx Ex01/Ex02/Ex03/Ex04 is the standard certification requirement for offshore electricians on UKCS installations.

Most Aberdeen-based offshore electricians work a rotation pattern — typically 2-3 weeks offshore followed by 2-3 weeks onshore. This rotation pattern is ideal for online preparation, allowing candidates to study during their onshore period and progress through EX Academy's simulations and questions at their own pace.

Offshore Inspection — Most Common Deficiencies

Experienced offshore inspection engineers know that the marine environment creates a characteristic set of recurring deficiencies:

• Corroded external earth tags — surface rust on earth tags is Category B; significant corrosion compromising connectivity is Category A
• Missing bolts on Ex d equipment — accelerated by vibration; any missing bolt is Category X regardless of how many remain
• Paint overspray on Ex d flamepaths — from maintenance painting operations; Category A if gap maintained, Category X if gap compromised
• Cable gland thread engagement loss — vibration causes glands to back off; below 5 full turns in an Ex d entry is Category X
• IP gasket degradation on Ex e equipment — UV, salt, and temperature cycling attack neoprene and silicone gaskets; degraded gaskets allowing moisture ingress are Category A (or Category X if moisture has reached live parts)
• Moisture ingress — condensation inside Ex e terminal boxes is Category A if no live parts affected, Category X if moisture on live parts

CompEx Renewal Offshore

CompEx certificates are valid for 5 years. For offshore workers, planning renewal well in advance is essential — assessment centre availability in Aberdeen can be limited, particularly in the autumn when many offshore workers are renewing before the winter season. Online preparation through EX Academy helps refresh knowledge ahead of renewal assessments, particularly for workers who may not have formally reviewed the IEC 60079 standards since their original certification.

Preparing for Your Offshore CompEx Assessment

EX Academy's 15 inspection simulations and 15 equipment selection scenarios are modelled on real offshore installation scenarios — Ex d motor terminal boxes, Ex e junction boxes on process decks, Ex de local control stations at wellheads, and IS transmitter connection heads on instrument loops. Working through these scenarios builds the systematic decision-making that the CompEx practical assessment tests.