Download Electrical Safe Working Practices

EKAS 2.18.2
Electrical Safe Working
Practices
UEE31307 Certificate III in
Refrigeration and Air Conditioning
Stage 2A
Units: UEENEEPOO1B, UEENEEPOO2B
Chris Hungerford
Saturday, April 29, 2017
Principle and purpose of risk management
• The process of hazard identification, risk
control and evaluation is the principle of
risk management.
• The purpose is the reduction of workplace
incidents.
2..18.2.A
Workplace Safety Checks
Step 1: Identify all hazards by:
•observing, inspecting, investigating,
communicating and consulting
•making a record of the hazards
identified.
2..18.2.A
The five step risk management process
Identify all hazards in this photo.
•electric shock,
•falls,
•slips,
•Others ?
Bent back
Sunburn
Jewellery
Thongs
2..18.2.A
Workplace Safety Checks
Step 2: Assess the risks
these hazards create by:
•assessing and prioritising the
risks
•dealing with the highest
priority risks first
•dealing with less risks or least
significant risks last.
•electric shock,
•burns,
•falls,
•sunburn,
•slips,
•back injuries,
2..18.2.A
Workplace Safety Checks
Step 3: Decide on measures to
control the risks by:
•eliminating the risk -if elimination of the
risk is not possible, select these control
measures in the following order of
preference:
(i)substitution,
(ii)isolation (not administrative),
(iii)minimisation by engineering means
(iv)application of administrative
measures,
(v)use of personal protective equipment
(PPE).
•electric shock,
•burns,
•falls,
•sunburn,
•slips,
•back injuries,
2..18.2.A
The five step risk management process
Workplace Safety Checks
Step 4: Implementing
appropriate control measures
should:
•adequately control the risks
•not create other risks
•allow workers to do their work
without undue discomfort or
distress.
•electric shock,
•burns,
•falls,
•sunburn,
•slips,
•back injuries,
2..18.2.A
Workplace Safety Checks
Step 5: Monitor the control
measures and review the process:
A: Monitor
•Have the control measures been
implemented as intended?
•Are the control measures adequate?
•Did the implementation of control
measures create other hazards or
risks?
B: Review
•Has anything changed over time
since the risk process was
implemented?
•Is the control of risks still adequate?
•Was the risk management process
conducted effectively?
2..18.2.A
The five step risk management process
Workplace Safety Checks
2..18.2.A
STANDARDS AUSTRALIA/STANDARDS NEW ZEALAND
AS/NZS3000: 2007, including ADMT 1, July 2009.
(known as the Australian/New Zealand Wiring Rules)
1.4.90 Voltage
Differences of potential normally existing between conductors and
between conductors and earth as follows:
(a) Extra-low voltage Not exceeding 50 V a.c. or 120 V ripple-free d.c.
(b) Low voltage Exceeding extra-low voltage, but not exceeding
1000 V a.c. or 1500 V d.c.
(c) High voltage Exceeding low voltage.
Standards online
http://www.saiglobal.com/online/
id.
3690699457
Password
IRCKRITFJP
User name
Skillstech
2..18.2.B
Extra Low Voltage
0-50vAC or 0-120vDC,
examples: control circuits, printed circuit boards, indicators, battery operated
devices, standby backup power, data, communications, small loads such as
fans, low power heaters, pool lighting
Types of Extra low voltage.
Safety Extra-Low Voltage (SELV): protective-separation, double insulation from all
circuits, other SELV, PELV and from earth. Example ELV lighting with own transformer.
Protected extra-low voltage (PELV): only requires protective-separation from all
circuits other than SELV and PELV but it may have connections to other PELV systems and
earth. In contrast to a SELV circuit, a PELV circuit can have a protective earth connection.
Example, control wiring in a large mechanical services switchboard.
Functional extra-low voltage (FELV) is not adequately protected from accidental
contact with higher voltages in other parts of the circuit. Therefore the protection
requirements for the higher voltage have to be applied to the entire circuit. Circuits include
those that generate an extra low voltage through a semiconductor device. Examples, switch
mode power supply, UPS, variable speed controls.
2..18.2.B
Low Voltage system
High Voltage
3 phases
11-33kV
240v each
415v between.
Neutral
Approx every 4-5
Pole MEN
Low Voltage.
2..18.2.B
Switchboard
Low voltage.
General load
ie. AC, TV, light
Low voltage.
Very high fault current near transformer
500kVA approx 13.5kA
High Fault Currents
At point of entry the resistance of the
service lines reduce the current.
Domestic approx = 10-6kA
Fault currents are limited by:
1. Size of transformer
2. CSA of conductors
3. Length of conductors.
In a domestic Switchboard cable resistance has
further reduce current to approx 5-3kA
2..18.2.B
At a domestic load
Fault current approx 1.5 -.5kA
High Voltage
11kv HV Switch room
2..18.2.C
11kV-240V Transformer
Can be: pole mounted, Pad mounted,
or in a transformer room
High voltage appliances
•
•
•
•
Microwave ovens………..2000V
Gas igniters ……………….15kV
Neon lighting………………10kV
Electro static devices
– Photocopiers
– Spray painters, powder coating
– Dust suppression ………….10kV
2..18.2.C
Touch Voltage
Touch voltage is caused by a fault current in
a conductive material establishing a
voltage between an earth contact point
(feet) and another part of the body (hand)
in contact with the energized material.
2..18.2.C
Step Potential
When current is flowing thru
the ground due to a
ground fault, the voltage
difference developed
between two points on the
ground separated by the
distance of one pace is
know as step potential.
2..18.2.C
Creepage
Creepage is the shortest distance between
two conductive parts and the surface of an
insulator.
2..18.2.C
High Voltage Procedures
When working near HV.
• Only be carried out on the authority of certified access
permits and switching schedules.
• Written lock out, isolation & switching events
• Safety earthing, location in the field & methods of
earthing plan.
• Erection of safety barriers.
• Identify any personal or business that will be interrupted.
• All persons required to enter the work area are to sign
the Permit to work access form.
• When complete, all persons required to enter the work
area also sign another form giving written authority for
the re-energising of the supply.
2..18.2.C
•
•
•
•
•
•
•
•
2..18.2.D
Fibre Optics
Fibre optic cables consist of glass or polymer cores that should be treated
equally with “medical sharps”.
Keep all food and beverages out of the work area. If fibre particles are
ingested they can cause internal haemorrhaging.
Always wear safety glasses with side shields to protect your eyes from fibre
shards or splinters. Treat fibre optic splinters the same as you would treat
glass splinters.
Never look directly into the end of fibre cables – especially with a
microscope – until you are positive that there is no light source at the other
end – having tested it with a power meter. Use a fibre optic power meter to
make certain the fibre is dark. When using an optical tracer or continuity
checker, look at the fibre from an angle at least 6 inches away from your
eye to determine if the visible light is present..
Do not touch your eyes while working with fibre optic systems until your
hands have been thoroughly washed.
Only work in well-ventilated areas.
Keep all combustible materials safely away from the curing ovens and
fusion splicers.
Thoroughly clean your work area when you are done.
Class 3A Lasers
Lasers in this class are mostly dangerous in
combination with optical instruments which
change the beam diameter or power
density. Output power does not exceed
5 mW. Beam power density may not
exceed 2.5 mW/square cm. Many laser
sights for firearms and laser pointers are in
this category.
2..18.2.D
3 Common Low Voltage Electrical Hazards.
• Electric Shock.
• Arcing : a short circuit can cause an intense arc of
electrical energy and when released will result in burns.
Fault currents of up to 20 times the rated
can flow, Heat = I2R.
• Toxic Gases: may be emitted during arcing which
can cause adverse effect to a target human organ, may
also contain carcinogens.
2..18.2.E
Risk with low voltage
Electrical hazards: Electric shock, Arcing, toxic gases.
1.
2.
3.
4.
5.
6.
7.
8.
2..18.2.E
Exposed electrical parts
Contact with overhead services
Defective/inadequate insulation
Improper earthing of equipment
Overloaded circuits
Damaged test equipment and tools
Lack of training
Work not as per Australian & New Zealand standards.
Controlling Low voltage Hazards.
The essential element for creating a safe work
environment is to:
• de-energise,
• proving the circuit is dead, and
• locking out of electrical equipment before
making repairs.
2..18.2.E
Restrictions in working Live.
ELECTRICAL SAFETY REGULATION 2002
11 Requirements for electrical work
An employer or self-employed person must ensure that,
unless the circumstances required under this division for
the performance of live work apply, live work is not
performed.
Maximum penalty—40 penalty units.
2..18.2.E
Control measures for working live.
As per Regulation 12 “Requirement for performance of live work”, to perform live
work you must satisfy the following seven (7) questions:
1. Have you prepared a risk assessment?
2. Is your test equipment appropriate to perform live work? Minimum Cat III @ 500v ac.
3. Has your test equipment been maintained and confirmed that it is operating correctly?
4.
5.
6.
7.
2..18.2.E
Regulation 18.2(b) “the instrument is tested at least every 6 mths to ensure it is in
proper working order”, and Regulation 12.1(f) “the instrument is tested immediately
prior to work to confirm that the instrument is operating correctly”
Have you the correct PPE, (Safety boots, long pants, long sleeved shirt, insulated
gloves, safety glasses)? As per AS/NZS 4836 Safe working on low voltage electrical
installations.
Is the isolation point clearly identified?
Is the isolation point able to be reached without any obstructions?
Is the area where the electrical live work is performed clear of any obstructions?
Control measures for working live.
PPE.
Headwear complying with AS/NZS 1801.
Eye protection without metal frames and
complying with AS/NZS 1337.
Ear plugs or muffs
complying with AS 1270.
Insulating gloves
Gloves complying with AS 2225 and
insulated to the highest potential
voltage expected for the work being
undertaken, and
Flame retardant
clothing covering the
full body (including
arms and legs) and not
made from conductive
material or containing
metal threads.
Flame-resistant gloves
Gloves complying with AS/NZS 2161.4
and protected against heat or fire to the
highest level for the work being
undertaken and air tested each time
prior to use.
Shoes or boots complying with AS/NZS 2210.2
and selected and maintained in accordance with
AS/NZS 2210.1.
2..18.2.E
Bling
Watches, rings
Bracelets, neck chains
Ear rings, piercing
Harmful Dusts
• Excessive dust emissions can cause both health and
industrial problems:
• Health hazards
- Occupational respiratory diseases
- Irritation to eyes, ears, nose and throat
- Irritation to skin
•
•
•
•
•
2..18.2.F
Risk of dust explosions and fire
Damage to equipment
Impaired visibility
Unpleasant odours
Problems in community relations
Harmful Dusts
Not all dusts product the same degree of health hazard;
their harmfulness depends on the following factors:
• Dust composition
- Chemical
- Mineralogical
• Dust concentration
-On a weight basis: milligrams of dust per cubic meter of air (mg/m3)
-On a quantity basis: million particles per cubic foot of air (mppcf)
• Particle size and shape
- The particulate size distribution within the respirable range
- Fibrous or spherical
• Exposure time
2..18.2.F
Harmful Dusts
Excessive or long-term exposure to harmful respirable
dusts may result in a respiratory disease called
pneumoconiosis.
• Silicosis - Silicosis is a form of pneumoconiosis caused by the dust
of quartz and other silicates. The condition of the lungs is marked by
nodular fibrosis (scarring of the lung tissue), resulting in shortness of
breath. Silicosis is an irreversible disease; advanced stages are
progressive even if the individual is removed from the exposure.
• Black Lung - Black lung is a form of pneumoconiosis in which
respirable coal dust particles accumulate in the lungs and darken
the tissue. This disease is progressive. Although this disease is
commonly known as black lung, its official name is coal worker's
pneumoconiosis (CWP).
• Asbestosis - Asbestosis is a form of pneumoconiosis caused by
asbestos fibres. This disease is also irreversible.
2..18.2.F
Harmful Dusts
Reducing employee exposure to dust can be
accomplished by three major steps:
• Prevention.
• Control Systems, dust collection systems, wet dust
suppression systems
• Dilution or Isolation.
2..18.2.F
Safety characteristics of Electrical testing devices
Arc from transients (lightning, load switching)
Protection: Independent certification to meet CAT III-1000 V or CAT IV 600 V
Voltage contact while in continuity or resistance
Protection: Overload (fuse) protection in OHMs up to the meter’s volt rating
Measuring voltage with test leads in current jacks
Protection: High energy fuses rated to the meter’s voltage rating
Shock from accidental contact with live components
Protection: Test Leads double insulated, recessed / shrouded,
finger guards, CAT III – 1000 V.
2..18.2.G
Safe use of Electrical device
•
•
•
Don’t work alone.
Choose the correct device & range
Practice safe measurement techniques.
– Always connect the grounded lead first, hot second.
– Disconnect the hot lead first, grounded lead second.
•
Use the three-point test method.
1. Test known circuit,
2. measure target circuit,
3. then re-test known circuit.
2..18.2.G
Electricity Safety Regulation 2002
18 Employer or self-employed person to ensure suitability of testing instruments
(1) This section applies to the following—
(a) an employer of a person required to perform tests on electrical work or safety
equipment;
(b) a self-employed person required to perform tests on electrical work or safety
equipment.
(2) The employer or self-employed person must ensure—
(a) the test instruments used for the testing are designed for, and capable of
correctly performing, the required tests; and
(b) if a testing instrument can not be visually confirmed as being correctly
functioning and safe—that the instrument is tested at least every 6 months to
ensure it is in proper working order; and
(c) records of tests performed are kept for at least 5 years.
Maximum penalty for subsection (2)—40 penalty units.
2..18.2.G
SECTION6
TE ST E Q U I PM E NT
AS/NZS 4836:2001
6.2 SUITABILITY OF EQUIPMENT
Test equipment shall pose no danger of electric shock to personnel or damage to the
electrical equipment during testing.
Test equipment shall comply with the following:
(a) Test equipment used in hazardous areas shall be of an approved design and shall be
clearly marked as being suitable for use in such locations.
(b) Test probes and other equipment shall be designed and selected so that they cannot
inadvertently short circuit between energized conductors and energized conductors
and earth.
The terminals of test equipment should be shrouded and all other test sockets on
measuring instruments should be designed so as to prevent inadvertent contact with
any energized test socket and/or conductor when the equipment is in use.
Where appropriate, test leads and testing devices should be provided with suitable
overcurrent protection.
NOTE: AS/NZS 2381 specifies requirements for the use of electrical equipment in
hazardous
2..18.2.G
Care and Storage
• Always handle carefully.
• Practice cleanliness
• Protect from knocks.
• Store in a dry place.
• Replace batteries yearly.
• Remove batteries if you plan not to use your meter
for extended periods.
• Never replace the internal fuse with a larger fuse.
2..18.2.G
Further reading: Workbook Risk management
Questions: Workbook, Topic 2, Q1-Q51.