53.1 All works to be carried out over water or at a height greater than [2.0m] above the ground level, must be performed from a properly constructed and maintained working platform.
Safe access to all points of work should be provided in the form of suitable ladders/ stairways located at appropriate interval which should not be more than 15 mtr.
53.2 The working platform shall be, - closely boarded,
- at least [0.7m] wide if used only as a footing,
- if used to store materials the width of the platform should be plus [0.7m] in addition to existing,
- provided with toe-boards of minimum [0.15m] in height,
- provided with handrails at and knee rails at [0.40 m] above the board, - constructed as close to the structure or building as possible.
53.3 Boards to be used on the platform shall be,
- of a suitable thickness, in due consideration of the spacing of supports beneath, - supported by at least three (3) transom, (or cross-supports),
- not project beyond the last support by more than twice their thickness, - be adequately fastened to prevent slippage or movement during use, - wherever possible, not overlap another board,
- be free from cracks, twists, holes or other defects which may affect the load bearing strength,
- protected from weathering by means of a clear preservative.
Boards shall never be painted as this disguises defects.
53.4 All working platforms shall be kept clean and free from grease, oil, rubble, debris or rubbish to ensure safe movement for personnel performing the works.
53.5 Mobile Platforms: The height of the mobile platform shall not be greater than [3 times] the shorter base dimension. Mobile tower scaffolding shall be fitted with lockable wheels.
54.0 ELECTRICITY
The contractor shall appoint a competent person to the satisfaction of the engineer, as the authority on site who will be responsible for the control of all maintenance and repairs to any electrical switchboard, distribution board, hand tools, etc.
54.1 Power Supply
If the authorities supply electricity, it will be provided at a point which would be determined by the engineer, the supply would be of 230V, 50Hz, single phase or of 415/ 433V, 50Hz, three phase. Power distribution beyond this point shall be through armoured cable only. No deviation on this would be permitted. The provision of all connections and equipment required beyond this point shall be responsibility of the contractor and be in accordance with these safety conditions and comply strictly with the current Indian Electricity Rules.
54.1.1 All power distribution cables should be taken above the overhead with sufficient headroom.
54.1.2 All switch boards, extension boards, etc. should be protected from rain and water. No water logging should be allowed around switch boards.
54.1.3 Earth leakage, Circuit breakers should be provided on all distribution boards and main switch boards.
54.1.4 All fuses shall be of good quality and confirm to correct ratings, use of makeshift wires or conductors as fusewire is strictly prohibited. MCBS are better than ordinary fuses and shall be preferred.
54.1.5 In new installations a totally enclosed switchgear is recommended.
54.1.6 Electrical maintenance workman must use wooden platforms insulated tools and rubber boots. Working on energised circuit/ live wires is strictly prohibited.
54.2 Electrically Operated Hand Tools
All electrically operated hand tools will be periodically inspected by the contractor and properly earthed prior to their use.
54.2.1 Use of lighting circuits for portable tools shall not be permitted.
54.2.2 Portable tools shall not be used near inflammable vapour or gases.
54.2.3 All equipments shall be suitably earthed.
54.2.4 All tools shall be checked to ensure the supplied voltage is comparable to the machine’s design.
54.2.5 Electrical leads and connections shall be inspected for signs of damage or wear, and repaired or replaced accordingly.
54.2.6 At no time shall two or more power tools be connected to a single power plug.
54.2.7 For circuits having voltage over 250 V suitable warning labels should be posted such as “Danger-440V” Boards also shall be displayed during the repairs / maintenance.
54.3 Connections to Project Authority’s Power Sources
54.3.1 Before the contractor connects any electrical equipment to any power source belonging to the Project Authority he shall:
- Satisfy the engineer that the equipment is in good conditions,
- Inform the engineer, in writing, of the maximum current required and the voltage and phase of the equipment,
- Obtain the written permission of the engineer detailing the power sources to which the equipment may be connected,
- Satisfy the engineer that the cabling to all equipment are of adequate sizes of the power required, have earth conductors in addition to metallic armouring overalls and fitted with suitable connections,
- Satisfy the engineer that any electrical distribution system which he proposes to install and any electrical equipment which he proposes to use will not endanger persons or property.
54.3.2 Care of Cable
No electric cable which is used by the project authority shall be disturbed without prior permission of the engineer.
54.3.3 Periodic check shall be carried out for defective cables, cracked or perished insulation, loose joints in conduits, damaged fuse boxes and switchboards, loose pins, faulty sockets and defective earth wire. Kinking, twisting, binding or crushing of cables shall be avoided all the time.
54.3.4 Care of Equipment
No electrical equipment shall be left open or unsecured at the end of the day’s work.
54.3.5 Work at Night
For working at night adequate supervision, lighting shall be ensured by the contractor. Contractor’s employees will not be allowed to work on circuits at night unless special permission to the contrary has been obtained from the engineer.
54.3.6 Only authorised persons shall carry out operations and maintenance of electrical systems.
54.3.7 Work permit and isolation of the electrical system before taking up the work would be necessary for all works of electrical maintenance.
Temporary site supplies and permanent installation should be installed in accordance with The Indian Electricity Rules, SP 0030 – National Electrical Code of USA and other relevant Indian Standards.
The design and installation of electrical power systems shall be done by specialists as the conditions are more arduous than most.
Before work commences, an assessment of the following characteristics of the proposed installation are :
purpose, supplies and structure
external influences
compatibility of equipment
maintainability of equipment
The first matter to consider is the size and locations of electrical loads and the manner in which they vary with time during the project.
Only persons who are competent for the particular class of work should carry out the installation, operation, maintenance and testing of electrical systems and equipment.
All completed electrical installations must be inspected, tested and commissioned before being made available for use. The inspections and tests necessary are listed in IS-732 Part-III and Part I Section 10 of National Electrical Code (NEC) but the construction site user should satisfy himself that the tests have been carried out. Written certificates should be completed for these tests.
It is a legal requirement that all electrical systems must be properly maintained to ensure safety. Thus, inspection, test and maintenance must be carried out on a routine basis.
The following are general safety rules to be followed:
Electrical wiring jobs should be done by trained electrician.
Avoid over loading of electric circuits
Never use defective or worn out appliances.
Discard damaged cords and plugs
Check for damaged insulations and exposed wires.
Ensure earth wire is well connected
Don’t touch electrical switches and appliances with wet body.
Low voltage 24V equipment should be used in confined spaces
Electrical equipment used in flammable atmosphere should be of flameproof construction.
Never permit a person to work in the proximity of any electrical circuit which may come in contact with him in the course of his work
Whenever work is to be done on an electrical circuit, the circuit should be isolated and fuses removed.
As far as possible all temporary electrical cables should be buried to a depth of two feet or layed overhead to a height of 10 feet.
All electrical wires layed on the surface should be protected from damage due to vehicles passing on them / mechanical damage.
Proper plugs should be used for tapping power supply. Inserting the leads into the sockets should be prohibited.
Hand lamps should be provided with guards over the bulb to protect from mechanical damage.