13.2　General Items

13.2.1　Cabling shall be in accordance with the following requirements:

1　The cable must be free of twist，flattened armor，broken sheath and severe scratch or other defects.

2　Where the cable is directly buried，it must not be buried above or below the conduit in parallel.

3　Cable must not be laid at the temperature lower than the minimum temperature that is allowed for laying cables.The mean temperature in 24 hours prior to laying cables and the temperature at cable laying site shall not be lower than those specified in Table 13.2.1；if the temperature is lower than the specified value，measures shall be taken accordingly.

4　Proper spare length shall be reserved at the end or joint of power cable.

13.2.2　The oil sample for oil-filled cable shall pass the test.The oil pressure in oil-filled cable should not be lower than 0.15MPa，and the oil delivery valve shall function flexibly.The pressure gauge shall indicate correctly and all the conduit joints shall be leak-free.A certain amount of oil pressure shall be kept in the cable during cabling.

13.2.3　Cabling on the cable bray and bearer shall be in accordance with the following requirements:

1　The bending radius of cable tray at its bend shall not be less than the minimum allowable bending radius of cable in the tray.Refer to Table 13.2.3 for the allowable minimum bending radius of cable.

2　High and low voltage power cables，heavy and weak current cables shall be arranged in different trays according to the require sequence.In general，they should be arranged from the bottom up.Power cable shall be laid on the bearer for more than 1 layer and on tray for more than 2 layers.

3　AC single core power cables shall be laid on the bearers on the same side.Where they are arranged in the form of close equiangular triangle，they shall be bond with binding band every 1m.

4　Anti-jamming measures shall be taken as designed for the cable lines that require so.

13.2.4　The fastening of cables on the tray and bearer shall be in accordance with the following requirements:

1　Where the cable is inclined over 45°，the spacing between the fastening points shall not exceed 2m.

2　Where the cable is arranged horizontally，it shall be fastened at both ends and on both sides at the bend.

3　Where the cable is arranged vertically，the spacing between fastening points shall not be more than those specified in Table 13.2.4.

4　The fixture for single-core cable or phase-splitting lead-sheathed cables after phase-splitting of the AC system shall not form a closed magnetic circuit.

5　Insulating gasket shall be installed at the fastening position for the cable that the sheath needs to be insulated.

13.2.5　Laying of cables in conduit shall be in accordance with the following requirements:

1　Cable protecting tube shall be used when the cable is laid in the following positions:the positions where the cable enters the building，tunnel，penetrates floor slab and wall and other positions where physical damage may be caused to cable；the section that is less than 2m from the ground when the cable is led to the pole，equipment，outer surface of wall or the place in door where it is accessible to people.

2　The number of cables passing through the conduit shall be in accordance with design requirements.

13.2.6　Laying of cable in concrete trough shall be in accordance with the following requirements:

1　The joints between troughs shall be smoothed with concrete mortar.

2　The trough shall be filled with yellow sand.

3　The cables of different voltage classes shall not be laid in the same trough.

4　In every trough，only 1-2 high-voltage cables are permitted to be laid，when laying low voltage cable the occupancy rate of the trough shall not exceed 40%.

13.2.7　Laying of buried cables shall be in accordance with the following requirements:

1　The cable shall be laid beneath the frozen earth layer，and the surface of cable shall not be less than 0.7m from earth surface，and 1m when it passes through the farmland.

2　Along the cable route，measures shall be taken in the following circumstances:at the locations where the cable may be subject to physical damage，chemical affect，underground current，vibration，heat effect，corrosive material，pest and rat，etc.

3　The minimum clearance，whether parallel or crossed，between the cables，and between cable and other pipes，road，and building，shall be in accordance with design requirements.If there are no such requirements，the requirements in Appendix D shall be met.

4　Above and beneath the buried cable，a layer of soft soil or sand not less than 100mm thick shall be laid and protective cover shall be installed and with the covering width shall extend to 50mm on each side of the cable.

5　Sign shall be established at the interval of 50-100mm along the straight section of buried cable，it shall also be established at the cable ends，bend and the point it enters the building.

6　Power cables laid in parallel shall have the same length，model and specification，and arranged in order without physical damage.

7　The support of surface cable conduit along electrified railway or the bridge where electrified railway passes through shall be insulated with the metal structure of bridge.

8　In three phase four wire system，must not use three-core cable with another wire as the null line.

13.2.8　Both fireproofing and flame retardation of cable line shall be in accordance with the following requirements:

1　If there are requirement for fireproofing and flame retardation of cable line，such requirements must be met during construction.

2　If design requires using fire-resistant or flame-resistant cable，fire-proof material or fire barrier wrap shall be used for the both sides of cable joint and the 2-3m section of adjacent cables.

3　The cables for important circuit that are mostly laid in the special channel and enclosed fireresistant trough as required by design shall be laid according to design requirements.

4　Important cable trench and tunnel shall be sectioned or equipment with frame shield with soft refractory materials according to requirements.

5　The holes，through which the cable passes vertical shaft，wall，floor slab or electrical panel and cabinet，shall be tightly filled with fire-resistant sealing.