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International Diploma

SAMPLE RESOURCES

This RMS sample resources pack contains a selection of powerpoint slides together with a supporting lesson plan and are representative of the full set of RMS trainer materials for the NEBOSH International Diploma qualification.

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Element IC8 Electrical safety

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Learning outcomes

IC8.1 Outline the basic principles of electricity

IC8.2 Outline the dangers of electricity

IC8.3 Outline the issues relevant to the installation, use, inspection and maintenance of electrical systems

IC8.4 Outline the main principles for safe working in the vicinity of high voltage systems

IC8.5 Outline the main hazards, risks and controls associated with the use of portable electrical equipment

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Contents

IC8.1 Basic principles of electricity

IC8.2 Dangers of electricity

IC8.3 Installation, use and inspection of electrical systems

IC8.4 Safe working in the vicinity of high voltage systems

IC8.5 Portable electrical equipment

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Contents

IC8.1 Basic principles of electricity

IC8.2 Dangers of electricity

IC8.3 Installation, use and inspection of electrical systems

IC8.4 Safe working in the vicinity of high voltage systems

IC8.5 Portable electrical equipment

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Basic principles of electricity

• Difference between low and high voltage

• Potential difference, current, resistance, impedance, OHM’S law

• Basic electrical circuitry

• Earthing principles

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• Electricity is a facility that we have all come to take for granted, whether for lighting, heating, as a source of motive power or as the driving force behind the computer

• Used properly it can be of great benefit to us, but misused it can be very dangerous and often fatal

• Electricity is used in most industries, offices and homes and our modern society could now not easily function without it

• The normal senses of sight, hearing and smell will not detect electricity

• Making contact with exposed conductors at the supply voltage of 110V or 230V can be lethal

• The actual number of electrical accidents is small

Basic principles of electricity

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• The term high voltage usually means electrical energy at voltages high enough to inflict harm or death upon living things

• The Electrotechnical Commission and its national counterparts Institute of Engineering Technology, Institute of Electrical and Electronics Engineers and Verband der Elektrotechnik, Elektronik und Informationstechnik) define high voltage as above 1,000V for alternating current, and above 1,500V for direct current - and distinguish it from low voltage (50-1,000V AC or 120-1,500V DC) and extra-low voltage (<50V AC or <120V DC) circuits

Differences between low and high voltage

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Electrical distribution voltages

Source: Parliamentary Office of Science and Technology.

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• The flow of electrons through a conductor is known as current

• The electric current flows due to differences in electrical ‘pressure’ or potential difference as it is often known

• The unit of potential difference is called the volt, V

• One volt of potential difference exists between two points if one joule of work is done by each coulomb of charge in moving between them

• Potential difference is measured by an instrument called a voltmeter

Potential difference

Potential difference, current, resistance, impedance, Ohm’s law

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• Current is the flow of charge

• The unit of current is the ampere, A

• Current is measured using an ammeter

• Ammeters are connected in series with the part of the circuit through which one wishes to measure the current, I, and they have negligible resistance

Current

Potential difference, current, resistance, impedance, Ohm’s law

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• For any conductor, the ratio of the potential difference across the conductor and the current flowing through it is constant

• This constant is called the resistance of the conductor, R:

• The unit of resistance is the Ohm, Ω

Resistance

Potential difference, current, resistance, impedance, Ohm’s law

I

V(R)Resistance

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• As an alternating current passes round a circuit under the action of an applied voltage it is impeded in its flow

• This may be due to the presence in the circuit of resistance, inductance or capacitance

• The combined effect of which is called impedance and is measured in ohms

Impedance

Potential difference, current, resistance, impedance, Ohm’s law

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Impedance

Source: G Self. RMS SAMPLE

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• “For any particular conductor at a constant temperature, the current that flows through it is directly proportional to the potential difference applied across it”

• There is a simple relationship between electrical pressure (volts), current and resistance represented by Ohm's Law:

• Voltage (V) = current (I) multiplied by the circuit resistance (R)

Ohm’s law

Potential difference, current, resistance, impedance, Ohm’s law

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Basic electrical circuitry

Source: RMS.

By Ohm’s law:Resistance

VoltageCurrent

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• Resistance in a circuit is dependent on many factors

• Most metals, particularly precious metals, allow current to pass very easily

• These have a low resistance and are used as conductors

• Other materials such as plastics, rubber and textiles have a high resistance and are used as insulators

• If the person is on, say, a dry concrete floor, resistance in the body will only be about 2,000 ohms and the resistance in the floor about 4,000 ohms, therefore:

Basic electrical circuitry

R

VI Amps0.04

Ohms 4000 2000

Volts230

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• The conductive mass of the Earth helps as a protective measure

• A conductor called an earth wire is connected to the system

• It is connected at one end to a plate buried into the ground and the other end connected to the metal casing of the equipment

• If for any reason a conducting wire touches the casing so that the equipment casing becomes ‘live’ the current will flow to the point of lowest potential

• By fitting the earth wire the path to this point is made easier as the wire has very little resistance and therefore an easier path

Earthing principles

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Unearthed electrical system

Source: G Self.

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Earthed electrical system

Source: G Self. Note: Harmonisation in Europe has now changed UK mains voltage to 230 Volts.

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NEBOSH International Diploma – Unit IC International workplace and work equipment safety

1 | P a g e

Lesson Plan – Day 2

TIME ELEMENT/TOPIC CONTENT RESOURCE/TASK

08.30 Review of overnight work Give feedback regarding content and structure of delegates work. General discussion with group

09.00 5.2 Risk assessment and use The need for conducting risk assessments in the use of work equipment Slides

Tutor asking questions to whole group and/or specific individuals to establish learning.

Small Group exercises: as sections of the material

are covered and as time permits, divide group

into small groups of 2 or 3 – set selected exam-

style questions relevant to topics being discussed.

Outline answers only required – collect whole

group feedback using flipchart as focus.

The risks associated with the use of work equipment arising from its initial integrity, the location where it will be used, and the purpose for which it will be used

The risks associated with the use of work equipment arising from its: incorrect installation or re-installation; deterioration; or, of exceptional circumstances which could affect the safe operation of work equipment

The risk control hierarchy relating to work equipment: eliminating the risks; taking 'hardware' (physical) measures (such as the provision of guards); taking appropriate 'software ' measures (such as following safe systems of work and the provision of information, instruction and training)

10.45 Break

11.00 5.3 Maintenance, inspection and testing

The hazards and precautions associated with the maintenance of work equipment

Slides

Tutor asking questions to whole group and/or specific individuals to establish learning.

Additional resource for students The Safety Assessment Federation Guidance document MLCC05 - In-Service Inspection Procedures -

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NEBOSH International Diploma – Unit IC International workplace and work equipment safety

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TIME ELEMENT/TOPIC CONTENT RESOURCE/TASK

http://safed.co.uk/technical-guides/machinery-lift-and-crane/

The three maintenance management strategies of: planned preventive; condition based; and breakdown

Factors to be considered in developing a planned maintenance programme for safety-critical components

The need for the maintenance of work equipment, including hired work equipment

The factors to be considered in determining inspection regimes having regard to the type of equipment; where it is used; and how it is used

The need for functional testing of safety-related parts, including interlocks, protection devices, controls and emergency controls

12.30 Lunch

13.30 5.4 Competence, training, information and supervision

The difference between training and competence Slides

Tutor asking questions to whole group and/or specific individuals to establish learning.

Circumstances when training is likely to be required including: induction; changes in work activities; introduction of new technology or new equipment; changes in systems of work; refresher training due to declining skills

Groups of people having specific training needs including supervisors, young and vulnerable persons

The relationship between competence and supervision (external and self-supervision)

The circumstances where there are specific training needs for certain hazardous types of work equipment (including chainsaws, woodworking machines, power presses, abrasive wheels, etc)

14.45 Break

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