PERFORMANCE STANDARDS

• Measure advancing occupational health are observed.

• Safety Procedures are practiced.

What Do You Already Know?

Let us determine how much you already know about observing occupational health and safety practices. Take this test.

What Do You Need To Know?

Read Information Sheet 2.1 very well then find out how much you can remember and how much you learned by doing Self-check 2.1.

Information Sheet 2.1

In the process of observing occupational health and safety practices, measures must be set to be followed by the students. Particularly, an electronics lab has these measures to highlight the manner of observing safety practices.

1. As a general rule all passages must be free of any obstruction that will hamper the movement of persons in the area. This provision also provides safety during emergency situations like fire and earthquake.

2. Treat every wire in the electrical system as live wire and act accordingly. Never attempt to work in any “live” electronic or electrical circuits.

3. All tools and equipment must be checked to be in A1 condition before they are lent to users.

4. All instructions must be centralized and must emanate from the person-incharge.

5. The shop is a place of work, so do not engage in a play while at work.

6. Never use tools or equipment you are not familiar with or you do not know how to operate. Always ask assistance from your teacher to avoid accidents.

7. Keep hand tools such as screw driver, files, and pliers on the table or tool cabinet and not in your pocket as it might hurt you or other people.

8. Use only tools that are in good condition.

9. Report accidents and injuries to your teacher no matter how minor.

10. Keep the work area always clean and orderly.

In every field of life whether in school, industries, and elsewhere, the observance of safety is a must. There are basic safety guidelines to prevent minor injuries such as cuts, burns, electrical shock and damage to eyesight as well as the loss of human lives. As good practice, make sure that a fire extinguisher and a first aid kit are available in case of injury or even fire.

Personal Safety Guidelines

These are general guidelines for all types of troubleshooting, installation and maintenance tasks. Take them seriously. They may keep you out of a dangerous situation.

1. Never work alone in any electronics project. Always have someone to keep an eye out for any potential problem.

2. Always use protective eyewear or safety goggles when appropriate.

3. Do not go barefoot when moving tool boxes or laboratory equipment.

4. Never assume that an electrical device is safe to handle. Perform your test with the device disconnected from the power source.

5. Some tests must be connected with power applied. Be extremely cautious when performing these test.

6. Do not wear jewelry of any kind. Remove all rings, wristwatches, bracelets, ID chains and tags, and similar metal items. Avoid clothing that contains exposed metal zippers, buttons, or other types of metal fasteners. The metal can act as a conductor, heat up, and cause a bad burn.

7. Work with one hand in your back pocket or behind your back when working on live circuits. This technique avoids a complete path for current flow that passes through the heart region.

8. Use an isolation transformer when working on AC-powered equipment. The transformer isolates the powered equipment from the power source.

9. Make sure all capacitors are discharged before beginning troubleshooting. Use a capacitor discharge tool to discharge the capacitor.

10. Use grounded line cords and polarized plugs with AC-operated equipment and circuits. They help to reduce the danger from hot chassis.

11. Keep hands off live circuits. Test all circuits with a voltmeter or test lamp before working on them.

12. Work only in clean, dry areas. Avoid working in damp or wet locations because the resistance of the skin will be lower; this increases the chance of electrical shock.

13. Do not wear loose or flapping clothing. Not only may it get caught, but it might also serve as a path for the conduction of electricity.

14. Wear only nonconductive shoes. This will reduce the chance of electrical shock.

15. Do not use bare hands to remove hot parts.

16. Use a shorting stick to remove high-voltage charges on capacitors. Capacitors can hold a charge for long periods of time and are frequently overlooked.

17. Make certain that the equipment being used is properly grounded with polarized plugs. Ground all test equipment to the circuit and/or equipment under test.

18. Remove power to a circuit prior to connecting alligator clips. Handling uninsulated alligator clips could cause potential shock hazards.

19. When measuring voltages over 300 volts, do not hold the test prods. This eliminates the possibility of shock from leakage on the probes. Safety is everyone’s responsibility. It is the job of everybody in and out of class to exercise proper precautions to ensure that no one will be injured and no equipment will be damaged.

ELECTROSTATIC DISCHARGE (ESD)

Static electricity is an electrical charge at rest on a surface. The static charge becomes larger through the action of contact and separation or by motion. The electrostatic discharge takes place when the charged body comes near or touches a neutral surface.

A surface can become charged through three means. The most common means is an electrical charge generated by friction. Rubbing two dissimilar materials together will generate an electrical charge. Walking across a floor or removing a garment will develop a voltage in excess of 5000 volts. It takes approximately 5000 volts to jump approximately 1/4 of an inch.

Induction is a second means of developing a charge. When a person handles a printed circuit board or electronic component wrapped in a plastic material, they induce a charge into the contents of the plastic wrap. When another person removes the plastic wrap, the sudden discharge results in ESD damage.

Capacitance is the third means of generating a static charge. Capacitance is inversely related to the distance between two surfaces. A low voltage can become harmful as one surface is removed further from the other surface or ground. When a circuit is picked up from a table its relative capacitance decreases and voltage increases. When the circuit is grounded again, damage will occur by the large voltage discharging that was generated when the circuit was originally lifted.

Metal oxide semiconductors (MOSs) are extremely sensitive to static charges, as are CMOSs, FETs, VLSI ICs, NMOSs, PMOSs, Schottky diodes, and ECL and linear ICs devices.

High humidity can increase surface conductivity, which reduces friction-generated static electricity. The increased humidity spreads the charge over a larger surface area, reducing the field intensity, and allows the charge to bleed off to ground.

Manufacturers have designed protective circuitry to help dissipate ESD using zener diodes and limiting resistors. ESD prevention requires the awareness and practice of the following procedures.

1. Treat all electronic components and circuits as static sensitive.

2. Do not touch the leads, pins, or components of printed circuit board traces.

3. Before handling a component or circuit, discharge yourself by touching a grounded metal surface.

4. Keep components in original packing materials until needed.

5. Never slide static components over any surface.

The following list identifies precautions required to minimize electrostatic discharge:

1. Before starting work on sensitive electronic equipment or circuits, the electronics technician should be grounded using a wrist strap to discharge any static electric charge built up on the body.

2. Always check manuals and package materials for ESD warnings and instructions.

3. Always discharge the package of an ESD-sensitive device before removing it. Keep the package grounded until the device is placed in the circuit.

4. Minimize the handling of ESD devices. Handle an ESD device only when ready to place it in the circuit.

5. When handling an ESD device, minimize physical movement such as scuffing feet.

6. When removing and replacing an ESD device, avoid touching the component leads.

7. Do not permit an ESD device to come in contact with clothing or other ungrounded materials that could have an electrostatic discharge.

8. Before touching an ESD device, always touch the surface on which it rests for a minimum of 1 second to provide a discharge path.

9. When working on a circuit containing an ESD device, do not touch any material that will create a static charge.

10. Use a soldering iron with the tip grounded. Do not use plastic solder suckers with ESD devices.

11. Ground the leads of test equipment momentarily before energizing the test equipment and before probing an ESD device.

How Do You Apply What You Have Learned?

Show that you learned something by doing this activity

Operation Sheet 2.1

Materials, Tools, and Equipment:

• Electronic components

• Electric wires

• Basic hand tools

• Measuring equipment

• Working tables

• Chairs and other lab facilities

Procedure:

1. Arrange electronic components based on safety considerations.

2. Arrange the basic hand tools together in a tool cabinet as to facilitate the measures regarding tools for occupational health and safety practices.

3. Arrange electrical wires according to standard safety measures.

4. Arrange electronic equipment considering occupational health and safety standards.

5. Arrange lab tables, chairs, and other related facilities in line with standard occupational health and safety practices.

6. Prepare an occupational health and safety practices report according to the result of the operation made.

Operation Sheet 2.2

Materials, Tools and Equipment:

• Meter for measurement

• Drawing papers

• A laboratory room

• Laboratory tables, chairs

• Tool cabinet

Instructions:

1. Using a meter, measure the dimension of the laboratory room and other facilities and make a layout of your room. Review the set occupational health and safety practices and relate it to the existing shop layout.

2. Using your observation and analyses, draw a proposed layout of your shop room showing the flow of shop activities focusing on occupational health and safety practices.

How Well Did You Perform?

Find out by accomplishing the Scoring Rubric honestly and sincerely. Remember it is your learning at stake!