This page refers to the requirements of Australian Standards and is intended to provide a quick reference for some of the  basic construction features and installation requirements for the most common protection techniques (however there may be other precautions or restrictions that apply to your installation).

Refer to the appropriate standards in your country for detailed construction and installation requirements for the various protection techniques.

Installation requirements applicable to ALL protection techniques include:

1. Read the hazardous area compliance certificate, especially any Conditions of Use.
2. All enclosure interfaces, eg, cable or conduit connections, must maintain the integrity and rating of the enclosure.
3. All circuits feeding into hazardous areas must be correctly isolated.
4. Correct earthing is essential, including equipotential bonding, instrument and protective earthing. Depending on your installation, you may also require lightning protection, intrinsically safe earthing, cathodic protection, static protection, etc.
5. Correct circuit protection (overcurrent, earth leakage, phase reversal, etc as appropriate) must be used.

• Robust construction. Be able to withstand, without damage, an internal explosion.
• Presence of precision machined flamepaths, which are designed with a minimum flame leakage path (FLP) and a maximum experimental safe gap (MESG) to quench the flame and cool hot gases before reaching the external explosive atmosphere.
• Ensure suitable layout and spacing of internal components to avoid pressure piling.
• Avoid invasion of flamepath by maintaining minimum 40mm clearance to other structures/obstructions.
• Use non-flammable grease used on flamepaths (silicon, lanolin, etc).
• Minimum 5 threads (tapered threads) or 8 (parallel threads) must be engaged on all flamepaths.
• Running couplings/nipples not permitted (unable to verify number of threads engaged).

• Quality construction with minimum impact resistance of 7nM and minimum IP rating of IP54.
• Minimum creepage & clearage distances.
• Maximum surface temperature limits (assisted by restricted electrical loadings and minimum enclosure volume).
• Limited quantities and ratings of terminals in junction boxes.
• Where more than 1 component makes up the equipment, such as a junction box with terminals, all components must be individually certified (component certificate numbers will have a “U” suffix).
• Restrictions on permitted alterations (consult with manufacturer if changes required).
• Minimum core sizes
• All unused terminals to be screwed tight.
• If at full current, do not bunch more than cores together.
• Earth fault protection required on motors (generally alarm in Zone 2 or shutdown in Zone 1)

• Ex”ia” – 2 fault tolerant, suitable for Zone 0
• Ex”ib” – 1 fault tolerant, suitable for Zone 1 (not Zone 0)
• Allows for the use of non-certified simple devices, maximum 1.2V, 100mA, 25mW
• I.S. barriers are required for all I.S. circuits (including simple devices in Australia)
• I.S. barriers located in safe area (or protected using a different technique)
• Segregation required between I.S. and Non-I.S. components
• I.S. components generally marked in BLUE colour
• Shunt Diode Barriers (using zener diodes) require high integrity earth, but Isolated Interface Barriers do not.
• Calculations generally required to match components and cabling when using individually certified components ("Entity Concept")
• An entire system may be certified together, including all components and cabling ("Integrated System")

• Enclosure must be purged or proven to be gas free prior to energisation.
• Separate protection techniques are required for support equipment (such as purge control unit, pressurisation accessories, gas detector, etc).
• Protected enclosure must maintain a minimum pressure of 300 pascal or 50% higher than the maximum working pressure, whichever is the greatest.
• Low pressure alarm sensor set at 50 pascal