ELECTRICAL SAFETY MEASURES

As a source of power, electricity is used in all aspects of life. In the home and at work, electricity provides the power for everything from domestic appliances to industrial machines, from office equipment to electric tools. When compared to the potential dangers of machinery and chemical substances, electrical hazards can be easily overlooked. Unfortunately, this neglect often causes serious accidents and loss of property. Many of these accidents can be prevented as they are mainly caused by electricity users who lack basic safety awareness.

This table reviews the industrial accident statistics involving electricity in the past decade.

Sources of electricity

The electricity we used is mainly supplied by local electricity companies, and is connected homes, working places, and other areas, through distribution systems.

Frequency: 50 Hz Voltage: 

Single-phase: 220 Volts (V) alternating current

3-phase: 380 Volts (V) alternating current

The electricity used in our homes and offices is single-phase alternating current, and 3-phase alternating current normally serves the industry.

Electricity principles

Ohm’s Law

A complete electrical circuit is composed of 3 elements: Current, Voltage and Resistance.

Their correlative relationship can be shown by the following formula:

The above formula applies to the human body during an electric shock, provided that the voltage remains constant and there is Resistance (R) in the human body. A reduction in resistance in

the human body will lead to higher electrical currents passing through it, and any injury will be more serious.

Electrical hazards

 Electric shock

Electric shock refers to the electricity passing through the human body, affecting the normal function of the heart, lungs and nervous system. Ventricular fibrillation caused by electricity is the main reason

for death from electric shocks. Electric shocks may indirectly lead to accidents, e.g. falling from heights and bruising due to body trauma etc.

Ventricular fibrillation involves a series of disordered contractions of the heart’s ventricular muscle

fibers, which prevents regular heartbeat. Under normal conditions, the human heart rate is from

around 60 to 100 times per minute. During an electric shock, the heartbeat may increase up to several

hundred times per minute. When the heart cannot sustain such rapid contraction and relaxation, it

may stop beating and cause death.

Burns

During an electric shock, the current passing through the body may lead to burns on the skin,

muscles or internal organs. As electric shocks and burns are closely related, preventative measures

should be considered together.

Fires and explosions

High temperatures caused by currents under abnormal conditions, may result in accidental fires

and explosions. The common causes leading to high temperatures include:

• Overloading of electricity

• Insulator breakdowns or short circuits

• Improper contact of electrical circuit

• Improper maintenance of

electrical appliances or wiring

• Poor ventilation, etc.

If flames, sparks or metallic solutions due to electric arc welding are not controlled, hazardous fires or explosions can occur.

Special process (electric arc welding)

Electric arc welding is commonly used for metallic welding and cutting. The various hazards from

welding or cutting include the following:

Hazards

• Burns

Sparks or hot metal fragments from arc welding or cutting may result in serious burns. Proper

protection is essential.

• Radiation

If proper eye protectors are not used while welding or cutting, radiation or other objects may hurt the

welder.

Safety measures:

Wear proper personal protective equipment, e.g. approved eye protectors, hand shields, leather aprons, leather gloves and safety shoes, etc.

Electric shock

It is dangerous to conduct the arc welding in a wet environment or on rainy days.

Safety measures:

• Avoid electric welding in such conditions.

• Earth the tools and equipment properly.

• Adjust the current required for welding to the minimum amount.

• Add an automatic voltage regulator to reduce the open-circuit

no-load voltage of the transformer output, reducing the chance of getting an electric shock.

• Poisonous fumes and gases Inhalation of poisonous fumes and gases during welding

or cutting may cause serious health problems.

Safety measures:

• Provide adequate ventilation.

• Use exhaust systems to remove poisonous fumes and gases.

Protective measures for prevention of direct electrical contact

The following procedures will prevent the human body from contact with electrical conductors, wiring, electrical sources, etc.

Protective measures

• Insulation

Shield the electrical conductor with an insulator to prevent direct contact

• Obstacles

Place obstacles to prevent any accidental contact with the electrical conductor

• Barriers or enclosures

Create barriers or enclosures that prevent any direct contact with the electrical conductor

• Placing out of reach

This prevents accidental contact with the electrical conductor

                                                                                                                                                        

VEHICLE ERGONOMICS TIPS

Introduction

About 80% of us will experience back pain at some stage in our lives. A number of work and leisure activities can contribute to back pain, but if you spend long hours driving, you may suffer from prolonged discomfort or pain in your back.







Sitting in the same position for long hours gripping the steering wheel and being exposed to vibration from the road can contribute to the wear and tear on your back, but there are things you can do to reduce your chances of suffering from back pain.

• Vary your work activities as much as possible during the day. Swap between the roles of driver and officer so that your posture changes. Try not to keep the same role for more than four hours.

• Take a break from driving every couple of hours.

• Make sure you get out of the vehicle as often as possible, move about and carry out small stretches if you can. Do not carry out any sudden intense physical activity (such as lifting, bending or stretching) without warming up first.

• Make small adjustments to your driving position every couple of hours.

• Follow this guide to make sure you are sitting correctly.



Driving Posture Guide

Start with the initial set up position, where adjustable:

• Steering wheel fully up and fully forward.

• Seat height at its lowest.

• Cushion tilted so that front edge is in the lowest position.

• Backrest approximately 30 degrees reclined from vertical.

• Lumbar adjustment backed off.

• Seat fully rearwards.


1. Raise the seat as high as is comfortable to improve your vision of the road.

l Check you have adequate clearance from the roof.

l Ensure you have a maximum vision of the road.

2. Move the seat forwards until you can easily fully depress the clutch pedal and the accelerator pedal.

• Adjust the seat height as necessary to give good pedal control.

3. Adjust cushion tilt angle so that the thighs are supported along the length of the cushion.

l Avoid pressure behind the knee.

4.Adjust the backrest so it provides continuous support along the length of the back and is in contact up to shoulder height.

l Avoid reclining the seat too far as this can cause excessive forwards bending of the head and neck and you may feel your thighs sliding forwards on the cushion.
 

5.Adjust the lumbar support to give even pressure along the length of the backrest.

• Ensure lumbar support fits your back, is comfortable with no pressure points or gaps.


6.Adjust the steering wheel rearwards and downwards for easy

l Check for clearance with thighs and knees when using pedals.

l Ensure display panel is in full view and not obstructed.


   7.Adjust the head restraint to ensure the risk of injury is reduced in the event of a car accident.

8.Adjust the rear view and side mirrors ensuring that they can be used without excessive straining of the neck or upper body.

Repeat 1-8 and fine tune as necessary

Be aware that many vehicles will not allow you as much flexibility of driving posture as you may wish. Particular vehicles may cause you to adopt a coping posture. For example, limited headroom forces a reclined posture, making the reach to the steering wheel a problem. This leads to excessive forward bending of the head and neck and a slouched posture.

SOIL CLASSIFICATION AND TESTING METHODS FOR EXCAVATION

This module describes the classification of soil and rock deposits based on site and environmental conditions, and on the structure and composition of the earth deposits. This appendix contains definitions, sets forth requirements, and describes acceptable visual and manual tests for use in classifying soils.

Key Definitions:


Cohesive Soil means clay, or soil with a high clay content, which has cohesive strength. Cohesive soil does not crumble, can be excavated with vertical side slopes, and is plastic when moist. The cohesive soil is hard to break up when dry and exhibits significant cohesion when submerged.


Fissured means a soil material that has a tendency to break along definite planes of fracture with little resistance, or a material that exhibits open cracks, such as tension cracks, in an exposed surface.


Granular means gravel, sand, or silt, (coarse-grained soil) with little or no clay content. The granular soil has no cohesive strength, cannot be molded when moist, and crumbles easily when dry. Some moist granular soils exhibit apparent cohesion.


Type A means cohesive soils with an unconfined compressive strength of 1.5 tons per square foot (tsf) or greater. Examples of cohesive soils are: clay, silty clay, sandy clay, clay loam, and, in some cases, silty clay loam and sandy clay loam. Cemented soils such as hardpan are also considered Type A. No soil can be Type A if fissured, subjected to significant vibration, or has been previously disturbed.


Type B means cohesive soils with an unconfined compressive strength greater than 0.5tsf but less than 1.5 tsf. Some examples are granular cohesionless soils including angular gravel, silt, silt loam, sandy loam, and , in some cases, silty clay loam and sandy clay loam. Type B also includes previously disturbed soils except those which would otherwise be classed as Type C.


Type C means cohesive soils with an unconfined compressive strength of 0.5 tsf or less. Some examples include gravel, sand, and loamy sand. Also included may be submerged soil or soil from which water is freely seeping, and submerged rock that is not stable.


Classification of Soil and Rock Deposits


_ Classification must be based on the results of at least one visual and one manual analysis conducted by a Competent Person.


_ In a layered soil system, the system must be classified in accordance with its weakest layer. However, each layer may be classified individually where a more stable soil lies under a less
stable soil.


Visual Tests

Observe samples of soil that are excavated and soil in the sides of the excavation. Estimate the range of particle sizes and the relative amounts of the particle sizes. Soil that is primarily composed of fine-grained material is cohesive material. Soil composed primarily of coarse-grained sand or gravel is granular material. Observe soil as it is excavated. Soil that remains in clumps when excavated is
cohesive.

Soil that breaks up easily and does not stay in clumps is granular. Observe the side of the opened excavation and the surface area adjacent to the excavation.

 Crack-like openings such as tension cracks could indicate fissured material. If chunks of soil spill off a vertical side, the soil could be fissured. Small spills indicate moving ground and can pose potentially hazardous situations.

Observe the area adjacent to the excavation to identify previously disturbed soil (i.e. evidence of existing utility and other underground structures).


Observe the opened side of the excavation to identify layered systems. Examine layered systems to identify if the layers slope toward the excavation. Estimate the degree of slope of the layers.

Observe the area adjacent to the excavation and the sides of the opened excavation for evidence of surface water, water seeping from the sides, or the location of the water table level.

Observe the area adjacent to the excavation and the area within the excavation for sources of vibration that may affect the stability of the excavation face.

OR-OSHA 302 Excavation Safety

This material is for training use only Manual Tests

Plasticity and Pat Test - Mold a moist or wet sample of soil into a ball and attempt to roll it into threads as thin as 1/8 inch in diameter. Cohesive soil can be successfully rolled into threads without crumbling. If at least a 2 inch length of 1/8 inch thread can be held on one end without tearing, the soil is cohesive. Spread a 1/8 or 1/4 inch thick sample of wet soil on the palm of the hand. Wipe the
surface of the sample with a finger to remove visible water. With the palm facing up, slap the back of the hand moderately 5 to 10 times. If water rises to the surface of the sample (surface will appear shiny), then the soil is mostly cohesionless silt or sand. If no water appears, then the soil is mostly cohesive clay.


Dry Strength - Granular soil, when dry, crumbles on its own or with moderate pressure into individual grains or powder. Soils with clay content, when dry, crumbles into clumps which break up into smaller clumps but the smaller clumps can only be broken with significant force. If the dry soil breaks into clumps which do not break up into small clumps and which can only be broken with difficulty, and there is no visual indication the soil is fissured, the soil may be considered
unfissured.


Thumb Penetration - The thumb penetration test can be used to estimate the unconfined compressive strength of cohesive soils. This test should be conducted on an undisturbed soil sample as soon as practicable after excavating to reduce the chance of air drying the sample. If later the trench is exposed to moisture (rain, flooding, etc.), the soil classification must also be changed.

Type A soils can be readily indented by the thumb. However, they can be penetrated by the thumb only with very great effort.

Type C soils can be easily penetrated several inches by the thumb and can be molded by light finger pressure.

Other Strength Tests Estimates of unconfined compression strength of soils can also, be obtained by use of a pocket penetrometer or a hand-operated shearvane. Other tests can include drying and sedimentation.

SAFE MATERIAL HANDLING TECHNIQUES

 Manual Handling and Lifting

1.     Always use mechanical equipment in place of manual handling as

far as possible.

2.     Carry out a risk assessment of the potential hazards that would

be associated with the operations, including health hazards.

3.     Assess the manpower required to handle or lift the load safely,

and arrange the manpower accordingly.

4.     In handling hazardous materials, the workers shall be informed

of the hazards and the safety precautions.

5.     All relevant persons shall be trained in the proper methods of

lifting and carrying.

6.     Where teamwork is required, select the persons whose ages and

physical builds are compatible for teaming up. Co-ordinate the actions of the team members by giving necessary instruction/signal.

7.     Always lighten or suitably shape the load for manual handling as

far as possible. Keep a lookout for splinters, sharp edges, loose banding, and nails.

8.     The Clear path of obstruction and tripping hazards.

9.     Stack and secure goods safely on trucks, otherwise they fall off and injure passers-by.

10.     Always use proper protective equipment such as gloves, safety shoes, etc.

11.        Follow the following procedures whenever you lift a load:

(a) Stand close to the object. Have a firm footing with feet spread on either side of the load;

(b) Bend the knees and keep your back as straight as you can;

(c) Grasp object firmly. Be sure grip will not slip;

(d) Breath-in and throw the shoulders backward;

(e) Straighten the legs, continuing to keep the back as straight as you can;

(f) Hold object firmly close to the body;

(g) Always lift smoothly. Avoid jerky motions. Turn with feet instead of twisting back.

12. The following table lists a rough guideline on the loads for different sexes and ages that can be taken as safe if they are handled properly. However, when the handling is regular and frequent the loads should be reduced by at least 25%. Sex and Age Weight of Load

4.2 Slings and Slinging

1.     Only use slings which had been tested and marked with a safe working load. Inspect the condition of the slings before use. Ensure that the slings be examined every 6 months by a competent examiner.

2.     Never overload a sling. Before lifting, find out the weight of the load and the safe working load of the sling.

3.     Use the correct type and length of sling for the job.

4.     Pad sharp corners of the load to prevent damage to the sling.

5.     Do not use a sling which is damaged or there are broken strands.

6.     Always use suitable guide ropes to prevent spinning or swinging of the load being lifted.

7.     Place slings so that the tension is equaled throughout the sling immediately on lifting.

8.     Give signals to the crane driver which are definite and clearly understood by all workers engaged in the lifting operation.

9.     Never stand under a suspended load, and warn others to keep away.

10. Slings should be coiled or hung up after use and stored away from heat and damp.

11.   All scrap slings must be removed from the site as soon as possible.

12.  Adopt a Colour Coding System for lifting gear,

eg.:

Blue for Jan – Feb – Mar

Yellow for Apr – May – June

Green for Jul – Aug – Sep

Orange for Oct – Nov – Dec

 Red To be removed from site

White Equipment under quarantine in Main Contractor’ s central yard.

The Main Contractor’ s safety officer shall be responsible for ensuring that the appropriate colour codes are painted after checking with the updated register.

14.When using bandages as lifting gears, ensure that the safe working load as marked therein are not exceeded. Bandages should be inspected before use on each occasion by a competent person and be examined every 6 months by a competent examiner.

4.3 Handling of Chemicals and Hazardous Substances

1.     Always substitute hazardous chemicals with harmless or less hazardous ones.

2.     Enclose the process using chemicals, or provide other engineering controls such as local exhaust ventilation, a fume cupboard or a safety cabinet.

3.     Exercise great care in the storage and use of chemicals at all times because they may be explosive, poisonous, corrosive or combustible.

4.     Physically separate different chemicals.

5.     Store chemicals classified as dangerous goods in a properly constructed and approved dangerous goods store. Keep proper records of all chemicals and hazardous substances delivered, stored, and used on site.

6.     Unknown substances and liquids should be regarded as dangerous unless known to be otherwise.

7.     All containers should be clearly labeled to indicate contents. Never use a wrongly labeled container for chemicals.

8.     Smoking shall be strictly prohibited when handling dangerous chemicals.

9.     Check that you are wearing the correct personal protective equipment (PPE) before you handle chemicals. Refer to the Material Safety Data Sheet for safety precautions to be taken and the use of suitable PPE, such as gloves, rubber boots or respirators. A proper file of Material Safety Data Sheets should be kept on site.

10.   When opening containers, hold a rag over the cap or lid as some volatile liquids tend to spurt up when this is released.

11.    Wash before you eat and do not eat or smoke at your work location.

12.   If the skin is splashed with a chemical, rinse it immediately with plenty of clean water. The eye should be flushed out thoroughly with water followed by the immediate medical attention.

13.   Eye fountain, emergency shower and breathing apparatus should be available in the vicinity of the workplace.

14. Safety instruction for handling emergency situations should be displayed prominently in the chemical storage and workplace.

 Asbestos

1.     You may find asbestos in the following situations:

(a) as asbestos insulation or coating used for:

1.     thermal insulation of boilers;

2.     fire protection of structural steelworks;

iii. thermal and acoustic insulation of buildings;

(b) as asbestos insulating board used in a wide variety of places such as:

1.     fire protection on doors, protected exits, structural steelworks, etc.;

1.     cladding on walls, ceilings, etc.;

iii. internal walls and partitions;

1.     ceiling tiles in a suspended ceiling;

(c) as asbestos cement, which is found as:

1.     corrugated sheets (roofing and cladding of buildings);

2.     flat sheeting for partitioning, cladding and door facings;

iii. gutters and downpipes.

2.     Arrange a Registered Asbestos Consultant to conduct analysis and prepare an asbestos investigation report if you are not sure whether the material and boarding contain asbestos.

3.     As soon as asbestos is identified, the concerned area shall be closed off and any work in this area shall only be carried out by approved specialist contractors under continuous supervision by a Registered Asbestos Supervisor.

4.     Use working methods that keep asbestos dust levels as low as possible (e.g. use hand tools and avoid breaking boards).

5.     Wear suitable protective clothing including respirators when working with asbestos.

6.     Provide washing and changing facilities for workers, and arrange to allow the separation of a person from protective clothing. The cleaning of protective clothing shall be carried out in a suitably equipped facility located on the premises where work with asbestos is being done or in a suitably equipped laundry elsewhere, and if protective clothing is to be removed from the person for cleaning or disposal, it shall be packed in a suitable container and labeled.

7.     Do not eat, drink or smoke in an area with the suspected presence of asbestos dust.

8.     Pay attention to the waste collection and disposal to avoid increasing the atmospheric concentration of asbestos fibers. Put the waste in an impervious sack and bury it in a controlled tipping site. Asbestos collection and disposal shall only be carried out by approved specialist contractors.