Element C8.3 Installation, Use and Inspection of Electrical Systems

Transcription

1 .3 Installation, Use and Inspection of Electrical Systems

2 Duty Holders Electricity at Work Regs 1989 EWR Employers and Self Employed Comply with regs as far as they are under their control Managers of quarries As above, but only as far as the quarry or part they are managing Employees Cooperate with employer Comply with regs as far as they within their control

3 Construction Electricity at Work Regs 1989 Reg 4 Physical condition and arrangement of the components of a system during its life From design to decommissioning

4 Strength and Capability no equipment shall be put into use where its strength and capability may be exceeded May give rise to danger

5 Insulation and Protection All solids contain free electrons Many free electrons = good conductors Too few = bad conductors = insulators Rubber Plastic Glass Conductors must be suitably covered / insulated Depends on use, environment, voltage

6 Excess Current Protection Circuit breakers Detect specific level of current flow Set during manufacture Faulty circuit easily identified Tamper proof Expensive Need regular testing Affected by ambient temperature

7 Reducing Risk of Shock Protection from direct contact Contact with charged or energised conductor Insulation Barriers Out of reach RCD Protection from indirect contact Normally at safe potential, become dangerously live through a fault condition Earthed Double insulated

8 Reducing Risk of Shock Protection from external influences Adverse condition Environmental Index of Protection codes Finger / tool proof Reduced voltage and SELV Separated extra low voltage Tools readily available (110v etc)

9 Overload Excess Current Protection Normal healthy system Mechanically overloaded too many appliances = excessive demands Temp rises rapidly Breakdown in insulation resistance = fire Fault current Excess of current due to fault condition Heat > fire

10 Cutting Off Supply and Isolation Must be suitable means for cutting off supply to a piece of equipment NOTE: equipment may still be live Functional switch On / off switch Emergency switch Emergency stop Used where hazardous condition may occur Isolation Inadvertent reconnection is prevented Remains switched off

11 Excess Current Protection Fuses Designed to melt at predetermined temperatures Cartridge fuses Ceramic or glass with metal end caps Small No moving parts Not suitable for high fault current

12 Excess Current Protection Fuses Designed to melt at predetermined temperatures HBC Fuse High grade ceramic barrel Plated end caps Expensive Reliable

13 Fuses Excess Current Protection Designed to melt at predetermined temperatures Weak link in the circuit to protect people Current (Amps) = Power (Watts) Voltage (Volts) Use the nearest fuse just above current level 2, 5, 7, 10, 13 for appliances

14 Working Space, Access, Lighting Adequate provided at all electrical equipment Allow people to move freely without hazard Operation, maintenance Lighting Properly designed and permanent

15 Maintenance and Checks Law requires equipment to be maintained = User checks Formal visual inspections Combined inspection and tests

16 Maintenance and Checks User checks Report defects and do not use equipment Damaged cables etc Faulty switches Burn marks, discolouration Loose parts / screws

17 Maintenance and Checks Formal visual inspections As user checks but also Opening of plugs Correct fuse Cord grip Secure terminations Inspection of Cabling Covers, joints Earth connections Panel doors

18 Maintenance and Checks Combined inspection and tests Periodic testing As required Use, frequency, type etc. Risk assessment Maintenance programme required Records to be kept Competent persons

19 IEE Wiring Regs Institution of Electrical Engineers Code of working Regulation 17 th edition BSI collaboration = BS7671 Not a statutory requirement can be used for enforcement of EWR

20 SSOW On equipment made dead Lock off procedure Padlocks Unique key Prevents inadvertent activation Post signs to show other workers

21 On live equipment SSOW If danger could be present, work must be done with equipment made dead Work permitted with live equipment Voltage readings Authorised competent workers only Adequate information on the task Selection and use of suitable test equipment and tools

22 PTW Part of SSOW Safety precautions have been taken