Westpoort VCA Eindtermen Basis, VOL, VIL VCU Engels

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Electric shock injury and reaction to electric shock

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DC voltage is less dangerous than alternating voltage (in general)

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Fire and explosion hazard

- 110 V DC and 50 V AC are harmless (under dry conditions) (guideline) - Direct current causes larger arcs than alternating current in the event of short circuits

Influence of an electric current on the body - Voltage difference - Resistance of the surface, including footwear (linoleum and a rubber mat have a high resistance, an earthen, clinker covered floor or a concrete floor are highly conductive and therefore have a lower resistance) In the event of a current passing through, the affected person may be shocked and sustain injury - Being hit by flying material in the event of a short circuit - Being thrown away by the pressure wave in the event of a short circuit Causes of accidents when working with electricity - Defective and defective machines, equipment and pipes - Poor or missing earth connections - Incorrect installation - Direct or indirect contact with live parts - Injudicious use of electrical installations and/or materials - Inattention, carelessness and ignorance Secondary injury when working with electricity -

Safety measures when working with electricity - Physical shielding - Double insulation - Insulation - Earth leakage protection - Use of very low voltages - Grounding

Physical shielding By installing a shield or covering, live parts are made inaccessible

Examples -

Switch box

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Casing of a washing machine

Insulation Live parts are made inaccessible by surrounding them with non-conductive material that can only be removed by breaking it

Examples of insulation materials - Rubber - Plastic - Ceramics

Theory of electrocutions Factors influencing injury -

Path taken by the current through the body

Circuit breaker Detects grounding connection, as soon as current to earth exceeds a certain value, the earth leakage circuit breaker switches off the voltage

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Current

Duration of current passage

Influence of electric current of 30 mA: - Blood pressure increase, difficult, irregular heartbeat, unconsciousness, risk of cardiac fibrillation, cramping - Difference between direct and alternating voltage:

Limitations -

Does not provide absolute security

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Must be tested regularly

Provides no protection against overcurrent, heating and short circuit

VCA (SCC) Final objectives | Page 57 of 66