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## 8.9.4 Socket outlet stations 

Socket outlet stations shall be provided for power supply of maintenance equipment such as welding units, power tools and hand held lamps and for the places such as Bio-P tanks, aeration tanks, RAS station, outlet station, etc 

Socket outlet stations shall be provided for indoor and outdoor locations as follows; 

At least 1 pcs station for indoor industrial type rooms and 1 pcs outdoor for each 30 mt. 

The socket outlets shall be installed in a socket outlet station, a box made of glass-reinforced polyester. The box shall be in protection class IP65. 

The stations shall comprise the following socket outlets, each supplied from its own circuit breaker and ELCB: 

- one 230V 

- one 230V, CEE type 

- one 400V, CEE type. 

230V socket outlets for supply of household appliances and similar equipment shall be provided in all buildings and rooms of the plant. 

The number of 230V socket outlets shall be based on the area of each room and each socket outlet shall cover no more than 7 m$^{2}$, hence a room off 16 m$^{2}$ shall be provided with 3 socket outlets. 

400V socket outlets shall be installed where required due location of machinery, maintenance procedures etc. 

The socket outlets shall be equally distributed in the rooms. 

230V AC socket outlets , the socket outlets shall have active earthing contact. When a plug is not inserted, the plug holes shall be covered by a lid. 

230V socket outlets shall be 13A CEE-types, according to BS 1363. 

400V AC socket outlets , the socket outlets shall have active earthing contact. When a plug is not inserted, the plug hole shall be covered by a lid. If the plug is pulled out when loaded, arching shall be extinguished inside the unit and confined in the enclosure. 

Each socket outlet shall be combined with a load switch and leakage current relay. 

400V socket outlets shall be according to CEE and 25 A. 

## 8.9.5 Uninterruptible power supply (UPS) 

A UPS system shall be provided for the whole control and monitoring system and the instrumentation at the treatment plant, which is double conversion on-line type. It shall include automatic transfer switch, manual maintenance bypass switch. Design shall be based on microprocessor/DSP controlled “pulse width modulation” technique. 

The UPS system for the treatment plant shall ensure the operation of the control and monitoring system and protect the system from losing data in case of a power cut. UPS shall have a means of on-line test procedure to test battery condition and battery management system to ensure 10 years of battery life time. 

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