Electrical Safety on Construction Sites work sheet

What type of cable should be used for indoor use on construction sites, as specified in BS 6500?

• PVC or rubber sheathed

• Steel armored

• Aluminum sheathed

• Copper braided

Answer explanation

According to BS 6500, PVC or rubber sheathed cables are suitable for indoor use on construction sites due to their flexibility and durability, making them ideal for temporary installations.

What precaution should be taken if you have to use a 230 V power tool?

• Supply via an RCD

• Use a surge protector

• Use a voltage stabilizer

• Supply via a transformer

Answer explanation

Using a 230 V power tool requires safety precautions. Supplying via an RCD (Residual Current Device) helps prevent electric shocks by cutting off the power in case of a fault, making it the safest option among the choices.

What is one use for a 230 V supply on a large construction site?

• Battery charging equipment

• Lighting

• Heating

• Air conditioning

Answer explanation

A 230 V supply is commonly used for battery charging equipment on large construction sites, as it provides the necessary power to charge various tools and machinery efficiently.

What is one method of overcoming the problem of increased earth fault loop impedance?

• Use RCD protection locally

• Use longer cables

• Increase voltage

• Decrease current

Answer explanation

Using RCD (Residual Current Device) protection locally helps mitigate the risks associated with increased earth fault loop impedance by providing a safety mechanism that disconnects the circuit in case of a fault, ensuring user safety.

Temporary electrical supplies for construction sites must comply with which standard?

• BS 7671

• BS 6500

• BS 8000

• BS 6004

Answer explanation

Temporary electrical supplies for construction sites must comply with BS 7671, which is the IET Wiring Regulations. This standard ensures safety and proper installation of electrical systems in construction environments.

What is the voltage between contact and earth on a 110 V supply?

• 55 V

• 110 V

• 220 V

• 0 V

Answer explanation

In a 110 V supply system, the voltage between contact and earth is typically half of the supply voltage due to the system's design. Therefore, the voltage is 55 V, making it the correct answer.

Which type of cable is specified for indoor use in BS 6500?

• PVC or rubber sheathed

• Steel armored

• Aluminum sheathed

• Copper braided

Answer explanation

BS 6500 specifies that cables for indoor use should be PVC or rubber sheathed due to their flexibility and insulation properties, making them suitable for various indoor applications.

What is a precaution for using a 230 V power tool?

• Supply via an RCD

• Use a surge protector

• Use a voltage stabilizer

• Supply via a transformer

Answer explanation

Using a 230 V power tool requires precautions to prevent electric shock. Supplying via an RCD (Residual Current Device) ensures that any leakage current is quickly cut off, enhancing safety compared to other options.

How can you overcome increased earth fault loop impedance?

• Use RCD protection locally

• Use longer cables

• Increase voltage

• Decrease current

Answer explanation

To overcome increased earth fault loop impedance, using RCD protection locally is effective. RCDs can detect earth faults and disconnect the circuit, enhancing safety without needing to alter cable length or current.

Do temporary electrical supplies for construction sites need to comply with BS 7671?

• True

• False

Answer explanation

True. Temporary electrical supplies for construction sites must comply with BS 7671 to ensure safety and proper installation, as these regulations govern electrical systems in the UK.