Mike Frain FIET MCMI Electrical Safety UK Ltd

Transcription

1 Mike Frain FIET MCMI Electrical Safety UK Ltd 1

2 INTRODUCTION: Mike Frain FIET MCMI Mike Frain Electrical Safety UK Ltd 540 Ecclesfield Road Sheffield S5 0DJ

3 Objectives Understand the hazards and effects of Electricity Understand the legal issues surrounding electrical safety Live Working and Safety in Electrical Testing Film Electrical Testing Electrical isolation procedures Film Isolation & Dead Working Electrical competence Scope mostly low voltage but will touch on High Voltage systems as well Workshops Sharing best practice Competent? How do we know? 3

4 Hazards HSE Electricity at Work Most electrical accidents occur because people are working on or near equipment that is: Thought to be Dead Known to be Live but those involved do not have adequate training or appropriate equipment, or they have not taken adequate precautions 4

5 HSE Statistics 68% Inadequate Working Practices Safe systems of work not in place Employer has not provided safe working procedures 19% Failure to Maintain 13% Miscellaneous 13% 19% 68% 5

6 The Hazard Danger to Life from:- Passage of Current through the body Blast and Heat effects of Short Circuits FIRE Ignition of flammable materials from electrical arcing 6

7 I ve had electric shocks and it didn t do me any harm... Three Important Considerations: 1. Current Path 2. Duration and frequency 3. Amount of Energy or Current flow 7

8 Amount of Energy or Current Amount Possible Effect >0.5mA No effect 0.5 2mA Threshold of Perception 6 13mA Threshold of Let Go 13 40mA Grip paralysis 30 75mA Respiratory system shuts down mA Ventricular Fibrillation occurs 1 1.5A Necrosis occurs 8

9 Accident victims can also incur Contact wounds Burns Respiratory difficulties Infectious complications Injury to bone through falls Heat necrosis Fractures caused by muscle contraction Permanent Injury to heart Permanent Injury to nerves Permanent Injury to eyes (Cataracts up to three years later!) 9

10 Electrical Injuries are Horrific 10

11 Electrical Injuries are Horrific 11

12 Electrical Injuries are Horrific 12

13 Blast & Heat effects of Short Circuits 13

14 Electrical Flashover Common cause is insulation failure Fault current Magnetic effects Arc temperature Up to 35,000 degrees Fahrenheit 4 times the temperature of the Sun Point of the arc is called arc flash Vaporized air and conductors creates a pressure wave called arc blast 14

15 Electrical Accidents Ratios Fatalities Major Injuries 600 Reported accidents

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17 Hazards introduced by other Electrical Workers Missing Phase shields and actuator taken off by colleagues, result 2 men in hospital

18 Hazards introduced by other Electrical Workers 18

19 Unnecessary Live Work

20 Finger Safe and Form 4 20

21 Changing Live Components High Level Busbar Trunking Signs of Previous Electrical Flashover

22 Testing near high power conductors Control Wiring Large Power bus bars Equipment Condition!

23 Transformer LV Tails

24 Transformer Secondary Blind Spot Leather burned through, rubber line is intact Sleeve burned through Example of a fire resistant shirt (5-6 cal/sq. cm) and gloves worn by a person who was burned in a secondary fault while hooking up some test leads to a pad mounted transformer. He came out of it with just some 2nd degree burns on his arm.

25 Legal Requirements Health and Safety at Work Act 1974 Electricity at Work Regulations 1989 Provision and Use of Work Equipment Regulations 1998 Management of Health and Safety at Work Regulation

26 Risk Assessment Need for Risk Assessment Legal requirement Management of Health and Safety at Work Regulations 1999 Many electrical workers embark on live testing or proximity work without a risk assessment Electrical accidents are expensive Lost Production Equipment damage Fines Damaged Brand Name (Priceless) 26

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28 What is Live Work? Work on or near any live part (other than one suitably covered with insulating material to prevent danger) when danger may be caused. 1st Paragraph to Regulation 14 EAWR

29 What is Live Work? Live Jointing Removal and replacement of fuse bridges and links Testing and running adjustments including measurement of circuit parameters, resetting of relays or safety devices and adjustment of controls wherever live low voltage conductors are present and accessible Testing for dead BS 7671 Testing and Inspection on live low voltage systems including: Measurement of Prospective and Short Circuit Currents Measurement of Earth Fault Loop Impedance Measurement of Voltage Inspections or any interactions which involves conductors that are insulated but where the work may adversely affect the integrity of that insulation. Installing or repairing equipment which is adjacent to exposed live low voltage conductors Switching??? 29

30 Work to be carried out Live only when: (a) It is unreasonable in all the circumstances for it to be carried our Dead; and (b) It is reasonable in all the circumstances for it to be carried out while the equipment is Live; and (c) Suitable precautions (Including where necessary, the provision of suitable protective equipment) are taken to prevent injury. 30

31 Special Circumstances Deciding to Work Live or Dead First - Identify the circuit or equipment to be worked on or near and the work to be done Yes Dead working is necessary Can the normal policy of dead working be carried out? No No Is it unreasonable for the work to be done DEAD? Yes Identify and assess the risks and methods for controlling them No Decide whether it is reasonable to work LIVE Yes No Decide whether suitable precautions can be taken to prevent injury Yes DEAD WORKING LIVE WORKING PERMITTED 31

32 Live Work Risk Assessment Assess the Risk Decide on the Precautions Decide if Live work can proceed

33 Damaged Equipment Equipment examined and in good condition? No LIVE work should ever be permitted where there are any doubts about the safety of cables and electrical equipment being worked upon or adjacent to those being worked upon. The examination can be visual but also using other senses. Smell and hearing can detect burning or electrical discharge. Signs of vermin or birds inside switchgear or water ingress is a definite prompt to STOP and investigate when the switchgear can be made dead and isolated. Approaches should NEVER be made to damaged cables Dangers of working in damaged live fuse boards and enclosures

34 Access / Space. Lighting & Environment OK? The work area should be clearly defined, with no tripping & slipping hazards and with good means of escape and illumination. Simple barriers & signs can be erected for the demarcation of work areas to keep non authorised staff away and also to protect electrical workers from interruptions at times when they need concentration. A hostile or wet environment will significantly increase the risk and severity of electric shock and should therefore be subject of a rigorous written risk assessment if those conditions cannot be controlled. Picture courtesy of International Produce Ltd

35 Work at height required? Working at height whilst carrying out LIVE work is always a special case for consideration for two reasons. 1. Electric shock or arc flash to a worker at height can bring about a fall with obvious consequences. 2. A flashover incident whilst working at height may mean that the worker cannot move out of the way because of the limited working space on access equipment. This may be the work platform of a scaffold or a mobile elevated work platform.

36 Tools, Instruments & Leads checked OK? Tools and instruments must be of the correct duty rating and their condition must be checked especially test leads. Arc damaged multi-meter

37 Are workers competent for the task A person shall not be engaged in any work activity where technical knowledge or experience is necessary to prevent danger or, where appropriate, injury, unless he possesses such knowledge or experience, or is under such degree of supervision as may be appropriate for that purpose having regard to the nature of the work. Regulation 16 Electricity at Work Regulation 1989 In the context of LIVE work, technical knowledge or experience means that the person should be properly trained and assessed in the techniques being employed but the person must also understand the hazards from the system and be able to recognise whether it is safe for the work to continue. It is the manager s responsibility to say whether the individual is competent or not and it is unlikely that this can be adequately demonstrated without a robust authorisation process for work of this nature.

38 Need for accompaniment Anyone undertaking work on or near energised electrical conductors will nearly always require some form of accompaniment by someone who can give assistance in an emergency. This implies a degree of competence such that the accompanying person can assist without danger to themselves or others. A requirement for a second person is to implement and maintain safe working procedures such as by preventing encroachment of non authorised personnel into the working area. PHOTO Picture courtesy of Freedom Group

39 Measuring Safely CAT I CAT II CAT III Dis. boxes Panels MCCs Electronic equipment and low energy equipment with transient protection Outlets and long branch circuits(more than 10m from CATIII source CAT IV Feeders, short branch circuits, distribution centres/panels meter Underground services, overhead lines and transformers Note that the demarcation between CATIII and IV is taken to be at the Meter or mains disconnect or at the Secondary of the service transformer 39

40 Film Electrical Measurement Safety 40

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42 Film Safe Isolation Procedure 42

43 Principal Requirements Work shall not commence on circuit conductors or electrical equipment until the Competent Person responsible for the isolation has: Identified, made them Dead and Isolated Applied Caution Notices to points of isolation Prevent Re-energisation Proved Dead at the point of work Take precautions to adjacent live equipment including applying Danger Notices Issued Permit where required by rules 43

44 Caution Notice example 44

45 Danger Notice example 45

46 Dead working Correct Instruments

47 Important Treat everything as Live until proven Dead Test at all points of work Test at the lowest power circuits first Do not enter high power enclosures to test. If this cannot be avoided then a full risk assessment must be carried out Never attempt to test cables at points of damage Allow capacitors to discharge 47

48 Rogue Circuits Locate and make Dead from ALL sources Test for transit wiring such as alarm circuits in complex control panels PROTECT YOURSELF 48

49 Circumstances that may require a LV Permit To Work to be issued Where the Person responsible for the isolation is not the one who will carry out the work Complex isolations where there may be more than one point of supply Isolations that involve third parties such as the Distribution Network Operator Designated hazardous zone where and explosive atmosphere may occur Metering circuits Switchgear with automatic changeover or remote control Switchgear and equipment controlled by phase failure relays Extensions to switchboards Isolations from Generators and UPS equipment 49

50 Complex Isolation G LOW VOLTAGE SWITCHBOARD INTERCONNECTOR 11KV CIRCUIT BREAKER UPS 50

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52 Competent Persons No Person shall be engaged in any work activity where technical knowledge or experience is required to prevent danger or, where appropriate injury, unless he possesses such knowledge or experience, or is under a degree of supervision as may be appropriate having regard to the nature of the work. Regulation 16 EAWR 1989 Technical Knowledge may include Adequate knowledge of electricity Experience Understanding of the system Understanding the hazards and precautions to be taken Ability to recognise at all times whether the work is safe to continue 52

53 Competence Skill Knowledge Attitude Training Experience Limitations Skills need to be updated as rules change Some skills fade over time 53

54 Who determines competence? Employer??? Employee??? Third party assessor??? 54

55 Competent Persons Persons Generally have a legal duty to not do work if they have any doubt about their own competency to do that work safely. Supervisors Have a legal duty not to allow work to be done unless they are certain to a person s competency. Managers Have a legal duty to ensure that work activities under their control are structured and controlled in a manner, which would ensure the work is always carried out by competent persons. Companies Have a legal duty to ensure that persons in their employ are competent or receive suitable training/supervision so as to avoid danger. 55

56 Authorisations High voltage switching Low voltage switching Electrical permit issue Sub-station entry Live testing Live working Access to distribution boards Access within control panels Electrical resets, repairs and isolations Lamp Changing???? 56

57 Contractors and sub-contractors By employing contractors and subcontractors it is the employers responsibility to either: Ensure that the individuals appointed to carry out the works are competent to do so, or The contracting company has procedure in place to vet their employees Many large companies have an approved contractor database 57

58 Food Industry Fatality A contractor s employee made direct contact with 40 mm of an uninsulated live cable at an in-line connector joint. He was removing a redundant cable from a trunking. The subsequent HSE prosecution in 2003 resulted in a fine of 220,000 and 30,000 costs to the company ordering the work for not ensuring that the subcontractor was sufficiently competent to perform such work and not ensuring a safe system of work was in place. The subcontractor who employed the electrician was also fined 25,000 for not ensuring a safe system of work was in place. 58

59 Competence - Workshop We have to consider: How do we know whether somebody is competent? Own Electricians Contractors OEM technicians Multi skills High Voltage Contractor Foreign Workers Training, academic achievement, age, experience? What specific proof of competence? How do we monitor performance- audits etc? 59

60 Foreign Workers

61 Live Work Risk Assessment - Workshop What live work can be allowed? What live work is forbidden? What is reasonable under regulation 14 EAWR 1989? Who takes the decision? Build a series of questions that will be required in a risk assessment Identify the workplace precautions that will be required before live work can commence 61

62 Dead Working - Workshop We have to consider: Who will carry out the isolation? How we will identify that person? How we identify, make dead and Isolate, what is an approved point of isolation Applied Caution Notices to points of isolation Prevent Re-energisation, how, control of locks, what if a lock cannot be applied? Proved Dead at the point of work, with what? when? Take precautions to adjacent live equipment including applying Danger Notices Issued Permit, under what circumstances and by who? 62

63 IDENTIFY, ISOLATE AND MAKE DEAD APPLY CAUTION NOTICES PREVENT REENERGISATION PROVE DEAD PRECAUTIONS TO ADJ LIVE EQUIPMENT INC DANGER NOTICES 6 STEP PROCESS FOR ELECTRICAL ISOLATION FILL IN THE BLANKS TO DESCRIBE HOW THIS WILL BE ACHIEVED ISSUE PERMIT TO WORK 63

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65 Safety Rules Model Survey Audit & Review Gap Report Training Drafting Publishing Approval 65

66 Safety Rules Model RULES PROCEDURE 1 PROCEDURE 2 PROCEDURE 3 GUIDANCE 66

67 Electrical Safety Rules HSG85 Electricity at Work Safe Working Practices Need to make sure that the rules fit the basic principles such as Competence, authorisation should be driven by the task and cover all electrical activities. Risk Assessment especially live work Set out simple basic rules & responsibilities Reflects relevant and local organisation personnel, working environment complexities. 67

68 Electrical Safety Rules Compact for electrical workers Not by a wish list must reflect what Will happen Procedures work on particular equipment or circumstances should be separate documents Fit in with existing rules/procedures. Based on current legislations and guidance. Approval of equipment, tools, instruments & PPE. 68