Urban nightscape lighting and lightning protection (two)

3 grounding and lightning protection measures

Grounding and lightning protection are closely related. To this end, we should pay attention to the following measures:

1) selection of grounding system

(1) the lighting device installed on the building body and directly supplied by the power supply inside the building, the earthing of the distribution system shall be in conformity with the grounding of the lighting device in the building.

(2) on the bridge and other structures, can not carry out a separate grounding lighting device, power distribution system should be grounded in the form of TN-S system, and suitable for equipotential bonding.

(3) road, square, park and other lighting distribution system should be grounded in the form of TT system.

(4) when the outdoor lighting lamp is larger than 20m, the grounding system of the power distribution system should adopt TT system. Less than 20m, the appropriate use of TN-S or TT system.

2) ground fault protection

(1) the protection of distribution lines shall comply with the requirements of GB50054.

(2) when using the TN-S grounding system, the overcurrent protection device can not meet the requirements of cutting off the fault circuit time, the residual current protection device should be used as the ground fault protection.

(3) when using TT grounding system, should adopt the residual current protection device for grounding fault protection, when the grounding resistance is small enough (Ia * RA = 50V when meet), the circuit breaker or fuse protection.

RA - exposed conductive part of the ground resistance and PE line resistance (omega);

Ia - to ensure the protection of electrical equipment to cut off the circuit fault current (A).

(4) the residual action current of the residual current protection device of the terminal branch of the outdoor lighting distribution terminal shall not be larger than 100mA, and the operating time shall not be greater than 0.4s.

3) when using TN-S grounding system, suitable for equipotential connection, and should be with the buildings or structures common earthing device; when using TT grounding system, the grounding resistance shall comply with the provisions of GB50054 Ia * RA = 50V requirements.

4 installation of the metal frame and lamps and lanterns, distribution box exposed conductive parts and metal hose should be reliably grounded, and there are signs.

5 safety and low voltage power supply should use safety isolation transformer, the secondary side should not be protected grounding.

6 lightning protection of night lighting device should meet the requirements of GB50057 and GB50343.

7, the existing building equipped with night lighting, lightning protection measures should be taken.

Four. Night vision lighting system lightning protection and lightning protection of the regular management measures

1 should be regularly by a qualified professional lightning detection agencies to detect lightning protection facilities. Assessment of lightning protection facilities are in line with national standards, the general requirements of lightning protection facilities should be tested once a year.

2 shall be responsible for the establishment of the prevention of lightning disaster, responsible for the safety of lightning protection, the establishment of the lightning protection system, the lightning protection system of the periodic inspection system, as well as the inspection and daily maintenance after the thunderstorm.

3 design and construction of mine facilities, should according to the characteristics of geology, soil, weather, environment and the protected object, considering the characteristics of lightning activities, the use of safe and reliable, advanced technology, reasonable design and construction.

4 new construction and installation of new equipment, lightning protection system should be re designed and built.