Questions and Answers
If a hazard may lead to an outcome of death or permanent disability, the level of risk is recognized as ____________ and this should be given the ___________ priority.
High, Highest
When implementing measures to control a risk, which of the following control measures should be implemented first?
What should occur as part of your overall risk management process if an incident occurs?
The following determine the effect of an electric shock on the human body...(You must select all of the correct responses)
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If a low voltage supply can’t be easily isolated, what methods can you use to remove a victim who is suffering from an electric shock?(You must select all of the correct responses)
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If a victim is suffering an electric shock from a high voltage installation, you should still attempt to rescue them by pulling or pushing them clear.
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Extra low voltage is regarded as completely safe, as the voltage and current levels are not sufficient to harm persons, livestock or property.
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An RCD is typically designed to trip when 30mA of earth current is detected. If a person was getting an electric shock of 30mA from an RCD protected circuit, the person would experience a shock with the following expected effects.
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The heat generated in a cable is determined using the following formula?
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If the current in a cable is doubled, the heat generated will increase by the following amount?
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If the current in a cable is tripled, the heat generated will increase by the following amount?
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The maximum continuous current a cable can carry without exceeding its temperature limits is called the..
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With all other things constant, what will happen to the temperature of a cable if the current flowing through it increases?
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Wiring systems shall be selected and installed to be suitable for the highest and lowest local ambient temperature. The designated ambient temperature for cable installations in Australia is:
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The best installation method for cable entry into a switchboard (from the following) is:
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As an electrician you are called out to the job below. The most likely cause of this fault is:
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The requirements for recessed luminaires are shown in which clause in AS/NZS 3000?
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Every permanently connected motor needs an isolation switch so that mechanical maintenance can be carried out when needed.
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Study Notes
Hazards and Risks in Electrical Installations
- A hazard leading to death or permanent disability is classified as High Risk, requiring the Highest Priority attention.
- The first control measure to implement for a risk is to eliminate the hazard altogether.
- After an incident, the risk management process should include monitoring and reviewing for improvements.
- The effects of electric shock on the human body depend on the following factors:
- Duration of the shock
- Amount of current flowing through the body
- Pathway taken by the current through the body
Electric Shock Response
- For low voltage supply incidents, safe removal methods include:
- Kicking the victim clear with the sole of your boots
- Pulling them clear using loose clothing
- Attempting to rescue a victim from high voltage should be approached with caution; it is deemed False to say you should rescue by physical means due to the high risk.
Current and Electric Shock Effects
- Extra low voltage is not regarded as completely safe; dangers still exist.
- An RCD (Residual Current Device) typically trips at 30mA of earth current, which can cause:
- Jolt similar to being punched, with cramping and possible breathing difficulties.
Electrical Properties and Formulas
- The formula for heat generated in a cable is H = I²Rt.
- If the current is doubled, heat generated increases by four times; if tripled, the increase is nine times.
- Current Carrying Capacity refers to the maximum continuous current a cable can handle without overheating.
- Increasing current through a cable leads to a rise in temperature, due to power loss (I²R) in the cable.
Installation Standards
- The designated ambient temperature for cable installations in Australia is:
- 40°C for installations in air and 25°C for underground installations.
- Best installation method for cable entry into a switchboard requires cutting individual holes with cable glands or fire retardant sealant for proper sealing.
Fault Diagnosis and Regulations
- Common causes of electrical faults include short circuits and high resistance joints.
- The requirements for recessed luminaires are specified in Clause 4.5.2.3 of AS/NZS 3000.
- Every permanently connected motor must have an isolation switch to facilitate maintenance safely.
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Description
Test your knowledge on hazards and risks associated with electrical installations. This quiz covers various important aspects of safety and protection in electrical systems. Ensure you're well-prepared to manage risks effectively.
