Unit Ex004

Maintain equipment in explosive atmospheres


This Unit of Competence covers the explosion-protection aspects for maintaining explosion-protected and associated equipment and wiring systems including plant maintenance schemes. It requires the ability to develop and manage maintenance programs incorporating strategies for inspections, repair/overhaul/replacement of components and recording of maintenance outcomes. This includes the ability to follow a maintenance program, work safely, carry out maintenance to Standards and manufacturer’s instructions and complete the necessary maintenance documentation.

This unit of competence is based on IEC 60079-17 and any other relevant standards that apply to this Unit of Competence.

The applicant shall have the level of technical education (or equivalent) attained, relevant to the application, through documents such as College Certificates and Trade Credentials etc. For an operative a minimum 3 years experience in industrial maintenance practice. For a responsible person a minimum 3 years experience in Ex maintenance practice relevant to the scope of the unit of competence being applied for taking into account the scope limitations.

Competence in this unit shall be assessed either concurrently with or after Unit Ex 001 – Apply basic principles of protection in explosive atmospheres. In addition, if the scope limitation requires, the achievement of competence in developing and managing general electrical/instrumentation maintenance programs will satisfy the prerequisite

Assessment of training and competence:

Each applicant will be required to demonstrate their competence through theoretical tests relevant to the competence applied for:

A rigorous theoretical exam will take the form of both Selected Response and Constructed Response questions. The duration of a knowledge test shall be based on the following:

    • Selected Response Questions – 2 minutes per answer
    • Constructed Response Questions – 3 minutes per short answer, 5 minutes per extended answer and 3 minutes per calculation.

The following is an example of the number of questions and duration of assessment for Unit 004 based on Unit 001 Competence having being granted for Flameproof Ex d, Increased Safety Ex e and Intrinsically Safe Ex i. The assessment time is based on an average of 2 minutes for selected response questions and 4 minutes for constructed response question.

Response A
(100% correct)
Response B
(80% correct)
Response C
(80% correct)
Total number
of items
5.23 4 6 2 12 28 Mins
5.26 Practical Assessment (inc 5.29) 4 Hrs
5.27 6 12 4 22 52 Mins
5.28 2 3 2 7 18 Mins
5.29 Practical Assessment (inc 5.26)  
  5 Hrs 38 Mins

Where multiple Units are assessed during the same assessment activity the questions used on one Unit need not be repeated in the assessment of subsequent Units. For example, where an assessment is undertaken for Unit Ex 003 and Ex 004 together it is not necessary to repeat those Clauses of OD 504 already covered in Ex 003 when assessing for Ex 004


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OD503 Fig 1B - The Pathway to obtaining an IECEx CoPC for units Ex 001 – Ex 010


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