Section 5 Electrical Installations in Hazardous Areas

501. Selection and installation of electrical equipment

1. Electrical equipment and wiring installed in hazardous areas are to be limited to that necessary for operational purposes. Only the cables and types of equipment described in this chapter may be installed. Selection and installation of equipment and cables in hazardous areas should be in accord- ance with following standards.

(1) KS C IEC 61892-1: Mobile and fixed offshore units−Electrical installations−Part 1: General re-

quirements and conditions.

(2) KS C IEC 61892-2: Mobile and fixed offshore units−Electrical installations−Part 2: System

design.

(3) KS C IEC 61892-3: Mobile and fixed offshore units−Electrical installations−Part 3: Equipment.

(4) IEC 61892-4: 2007 Mobile and fixed offshore units−Electrical installations−Part 4: Cables.

(5) KS C IEC 61892-5: Mobile and fixed offshore units−Electrical Installations−Part 5: Mobile

units.

(6) KS C IEC 61892-6: Mobile and fixed offshore units−Electrical installations−Part 6: Installation.

(7) KS C IEC 61892-7: Mobile and fixed offshore units−Electrical installations−Part 7: Hazardous

areas.

2. In selection of electrical apparatus for use in hazardous areas, consideration is to be given to:

(1) the zone in which the apparatus will be used;

(2) the sensitivity to ignition of the gases or vapours likely to be present, expressed as a gas group

;and

(3) the sensitivity of the gases or vapours likely to be present to ignition by hot surfaces, expressed

as a temperature classification.

502. Protection of electrical installations

1. Electrical apparatus used in hazardous areas is to be manufactured, tested, marked and installed in accordance with following standards and certified by an independent testing laboratory recognized by the Society.

(1) KS C IEC 60079-4: Electrical apparatus for explosive gas atmospheres−Part 4: Method of test

for ignition temperature.

(2) IEC 60079-4A: 1970 Electrical apparatus for explosive gas atmospheres−Part 4: Method of test

for ignition temperature−First supplement.

(3) KS C IEC 60079-10: Electrical apparatus for explosive gas atmospheres−Part 10: Classification

of hazardous areas.

(4) IEC/TR 60079-12: 1978 Electrical apparatus for

explosive gas atmospheres−Part 12:

Classification of mixtures of gases of vapours with air according to their maximum experimental

safe gaps and minimum igniting currents.

(5) IEC/TR 60079-13: 1982-01 Electrical apparatus for

explosive

gas atmosphere−Part 13:

Construction and use of rooms or buildings protected by

(6) KS C IEC 60079-14: Explosive atmospheres−Part 14:

and erection.

pressurization.

Electrical installations design, selection

(7) IEC/TR 60079-16: 1990 Electrical apparatus for explosive gas atmospheres−Part 16: Artificial

ventilation for the protection of analyser(s) houses.

(8) IEC 60079-17: 2007 Explosive atmospheres−Part 17: Electrical installations inspection and main-

tenance

(9) IEC 60079-19:

reclamation.

2006-10 Explosive atmospheres−Part 19: Equipment repair, overhaul and

(10) IEC/TR 60079-20: 1996 Electrical apparatus for explosive

gas atmospheres−Part 20: Data for

flammable gases and vapours, relating to the use of electrical apparatus.

(11) IEC 60079-25: 2003 Electrical apparatus for explosive gas atmospheres−Part 25: Intrinsically

safe systems.

(12) IEC 60079-27:

(FISCO).

2008

Explosive atmospheres−Part

27: Fieldbus intrinsically safe concept

(13) KS C IEC 60079-28:

Explosive atmospheres−Part

28: Protection of equipment and trans-

mission systems using optical radiation.

(14) IEC 60079-29-1: 2007 Explosive atmospheres−Part

ments of detectors for flammable gases.

291:

Gas detectors−Performance require-

(15) IEC 60079-29-2: 2007 Explosive atmospheres−Part 292: Gas detectors−Selection, installation,

use and maintenance of detectors for flammable gases and oxygen.

(16) KS C IEC 60079-30-1: Explosive atmospheres−Part 301: Electrical

General and testing requirements.

resistance trace heating−

(17) KS C IEC 60079-30-2: Explosive atmospheres−Part 302: Electrical resistance trace heating−

Application guide for design, installation and maintenance.

2. Equipment classified in accordance with the following protection classes may be used:

Table 7.1 Electrical protection type

3. Types of electrical equipment permitted should be determined according to the electrical hazardous area classification of the location in which the equipment is to be installed. Permissible equipment is shown by an "x" in Table 7.2. The use of type "o" is to be limited. For transportable appara- tus, protection type "o" is not to be used.

Table 7.2 Type of electrical apparatus used in hazardous zones

4. Group selection for electrical equipment is to be as follows:

(1) Group II should be selected for types "e", "m", "n", "o", "p", "q" and "s" apparatus.

(2) Group IIA, IIB or IIC should be selected for types "i", "d", and certain types of "n" apparatus according to table Table 7.3.

Table 7.3 Relationship between gas/vapour group and permitted equipment group

5. Electrical apparatus is to be so selected that its maximum surface temperature will not reach igni- tion temperature of any gas/vapour possibly presenting in the hazardous areas in which the elec- trical apparatus is located. The relationship among equipment temperature class, equipment max- imum surface temperature, gas/vapour ignition temperature is shown in Table 7.4.

Table 7.4 Relationship among temperature class, maximum surface temperature and ignition temperature

6. Electrical apparatus located in hazardous drilling well and mud processing areas is to meet at least Group IIA and temperature class T3.

7. Electrical cables are to meet the following:

(1) Only cables associated with type "ia" equipment are to be permitted in Zone 0 areas.

(2) Thermoplastic sheathed cables, thermosetting sheathed cables or elastomeric sheathed cables are to be used for fixed wiring in Zone 2 areas.

(3) Flexible and portable cables, where necessary, used in Zone 1 and Zone 2 areas are to be to the satisfaction of the Administration.

(4) Permanently installed, fixed cable passing through Zone 1 hazardous areas is to be fitted with conductive covering, braiding or sheathed for earth detection.

8. Explosion proof type or equivalent essential lighting is to be supplied from at least two final sub- circuits in such a way that failure of any one of the circuits does not leave the space in darkness. For lighting (explosion proof or equivalent type) in hazardous areas or spaces, switches are to be of the two-pole type and wherever practicable located in a non-hazardous area.