On the construction of the power problem Analysis

[Paper Keywords] Power analysis of construction safety measures
[Abstract] In this paper, the power problem in the construction of the relevant issues for analysis.


We all know that construction sites in the external environment is more harsh conditions, such as wind, rain, sun, water splash, dust etc is a disadvantage, coupled with the operation of motor vehicles on construction sites and machinery applications, a very prone to electrical equipment, shock and vibration, these are easily lead to electrical failure. construction site construction workers at work is often subject to rain, water splash, the skin moist, resulting in decreased body resistance, and these staff Most non-electrical personnel, lack of knowledge of electrical safety, while the site is a temporary supply line and the line, most of the overhead or for surface lines, these factors could easily lead to electrical shock.

1. Construction site risk analysis of electrical hazards
1.1 Construction organization design is not fully prepared
Pertinence, can not guide the construction, but rule of thumb erection of the line, causing electricity unreasonable, or even a security risk.

1.2 There are no warning signs hanging
Part in the construction and foreign lines is less than the required safety distance, did not take protective measures, there is no protective barrier to hang warning signs, protective material does not meet the requirements, did not use insulation materials, difficult to prevent the hard goods through.

1.3 Lighting system arbitrarily set
Shed most of the low site, the line height is less than 2.4 m did not use the 36 V below the safe voltage lighting circuits without using a dedicated circuit, wire soft lines, damaged aging, poor insulation; lighting fixtures random lines and erection of life electrical phenomena such as random access private pull more.

1.4 set up unreasonable distribution lines
Erection of scaffolding direct distribution lines or hash out the shelves, shallow burial depth of cable lines, laying down left and right side is not less than 50 mm thick yarn, buried cable leads to the ground 2 m to 0.2 m underground at the unprotected units tube; cable lines mopping the floor, pulling random access private, joint poor water resistance, no poles or wooden rods using concrete, electrical diameter of legs small, shallow buried depth, span over the provisions of poles of the terminal pole, corner Rod did not pull the installation of balance, lack of insulators on the pole, cross arm arranged on the confusion of lines.

1.5 part of the site next to zero protection is not standardized
Protection of the zero line does not lead to the switch box, electrical equipment do not live exposed parts of the protection of ground zero line do not duplicate or repeat the ground does not meet the requirements of grounding resistance not to shake table testing, protection of the zero line of the materials did not use the green / yellow color line to identify the difference.

1.6 Electrical Safety consciousness
Operator knowledge or do not understand electrical power technology, tinkering with electrical chaos, random access appliances, Luanla wires, playing live electronics, random repair of electrical, maintenance equipment, operator error: Connection received the case when the line of fire by mistake on the hand touches equipment or live parts or components used to take off the live wire fell on the ground, with wet hands or operate electrical equipment maintenance, using a stick instead of insulated tools and other operations jump format fuse: a knife, cut cut cut live wires, too close to the high-voltage equipment or power lines while operating at high voltage wires and inadvertently charged, use the bolt and other errors.

1.7 two levels of protection did not use three distribution
Power system is chaotic, distribution boxes, switch boxes used in material material difference, more hidden, the poor location of the box set, huddle around the construction materials, operation and maintenance very convenient; box size is small, close to electrical box; box not fitted with isolation switch; electrical equipment installed in the board, electrical appliances exposed, damaged more, especially the lack of some knife gate cover, operating extremely inconvenient, not safety, power distribution boxes, switch boxes identity is unclear , Lead free box, box measures without rain, rain can easily enter the cabinet, a multi-gate, power distribution boxes and switch boxes, switch boxes and electrical equipment distance.

2 construction site electrical safety measures
2.1 improve the temporary power of the pipeline construction design
Temporary power equipment or equipment for more than five and the total capacity of 50 kW and above, should be prepared temporary power construction design. Construction design should include a site survey, load calculations, design of distribution lines, power distribution equipment design, mine design, safe use of electricity, electricity design and construction plans and so on. understand the site topography, building locations provided by the power, to meet the construction needs to understand the amount of machinery equipment, capacity and layout of the scene to see construction provide relating to the underground pipeline location map and site plan the total construction planning. determine the total electrical power distribution box and distribution box location, and power lines laying wiring lines with total power distribution box and distribution box location setting principles , as close to the load center, so that the power loss, voltage loss, non-ferrous metals into the outlet near the minimum consumption of convenience, as close to the power supply, to avoid in dusty, low-lying water, impede vehicular traffic and construction areas. the cost of overhead lines low, easy to install, maintain, easy maintenance, easy to find and troubleshooting for the building and does not cross the construction site, does not affect the crane walking and vertical transportation vehicles place. cable lines are required for high reliability mechanical and electrical equipment required to prevent the construction across the building or place can not be used overhead lines. Links to free download http://www.hi138.com 2.2 to enhance electrical safety organization and management, the establishment of temporary power file
Files, including construction of temporary power separate preparation of the construction site temporary electrical construction design and related approval procedures, tests, information technology, including electrical engineering and technical personnel to the installation, maintenance and temporary power electrical engineering staff of various electrical equipment separate tests, the text, tests, and integrity of the content must be targeted, and tests on both sides of the signature and date. Safety inspection and inspection information, including the acceptance form temporary power engineering, electrical equipment, commissioning, testing and inspection information (mainly equipment and performance of insulation in good condition, the resistance value of regular testing records, checklists, etc. on a regular basis.

3 on the power distribution box and the wiring problem analysis
Temporary power system should adopt a "three control bipolar protection" system, which uses the total power distribution box, electrical distribution boxes, switch boxes three control levels while the total power distribution power distribution boxes and switch boxes were installed to implement conservation leakage protection of electrical equipment under normal circumstances can only switch box wiring in practice, some of the construction unit and electrical equipment as a more recent distribution of electric box electric box on the distribution of cluster directly in connection with this is unsafe. Also, according to <<security specifications>> requirement <wire lead from the pole into the distribution box should be worn to protect from the bottom into the pipe line, tube top made in the protection of water elbow is directly in some of the construction site under the Canadian pole cross arm, uses porcelain directly from the top of the lead wires into the wire out of the box without the jacket, Open water elbow. this is the same time must not be taken at the construction site, we often arbitrary intensity distribution box to see the wiring usually unlocked or locked but the key is not someone to manage = confusion inlet and outlet, regardless of road into the beam, without protection tube, choppy, chaotic chaos to take power, the power cord knife switch directly on the hook in the box = non-standard wiring, wire cutting head is too long, exposed conductors, "chicken wire" is serious wiring and electrical switch box does not match the requirements laid porcelain knife switch nut cover lost or incomplete a gate multi-machine, or even directly connected across the leakage protection switch on the knife under a leakage protection than outlet box with wire head residues, residual melt small tools, etc., or even stacked shoes, food and other debris have been removed load lines are still thrown in the box, near the exposed end of a thread switch electrical power distribution box in the layout of the other lighting and wiring problems on the construction site lighting is characterized by many points, a wide range of mobile and temporary strong, difficult to manage the on-site electricity for lighting large, prone to accidents in wet places and accessible places of the body charged shall not exceed the supply voltage lighting, portable lighting applications using the power supply voltage must not exceed and can not use self-coupling transformer transformer, and the other places should also be used in confined wet type dust with water, but we see that the plaster in the foundation stage, the ground is extremely wet, the workers do not cut off the power would hold the tie in the wood on the tungsten plug or oblique hanging freely placed, then dry hands live a hand-held lighting circuits leave the ground laying on the ground at random chaos dragged Luanla = passageways do not wear tube protection, dump trucks coming and going in the top, and even some aluminum sheath cable flowers using the site lines for the power cord some wires and tied wire on the lighting, iron on, right on another tree, lighting a serious line of aging, damaged insulation lighting line = middle joint, joints, plus protect the lighting circuit not no switch box, also no knife switch, while the light lines directly linked to the knife in the other device, or lighting circuits and earth leakage protection devices to connect to skip the knife switch on the lighting circuits within the site layout of temporary facilities is too low, free break joints, like the spider web-like pull, some even drying clothes hanging above it, etc. These illegal elephant uncommon, risks a lot, caused by the construction unit is responsible for much-needed attention
4 Conclusion
In the construction of electricity as a power, you can start all kinds of construction machinery, can be used for welding, cutting and heating in the winter of concrete methods for conservation, etc., can also be used for lighting, signals, alarms, communications and measurement, but electrical and posing a threat to people. Electric shock may result in casualties, electrical power equipment may damage or cause a fire, especially in building construction are temporary facilities, electrical equipment, outdoor operations and humid operating environment, combined with construction and low quality of the actual situation, so that the construction electrical safety issues become more prominent. strengthen the construction site electrical safety, reduce electrical accidents, to ensure construction safety is extremely important.


[References]
[1] IEC / TC 64. International Electrotechnical Commission IEC standard [S].

[2] Wang Ni. Low-voltage power ground fault protection [J]. Building Electrical, 1994, (13) :6-11. Links to free download http://www.hi138.com