Basic Cable Calculations Quiz

What is the first step when performing basic cable calculations ?

• Determine the design current of a circuit and select an appropriate protective device.

• Identify the appropriate rating factors to consider in cable calculations.

• Perform basic cable calculations including voltage drop.

• Select an appropriate size of cable from the relevant tables in BS7671.

How are the environmental / installation conditions which will affect the cable taken into account when performing cable calculations?

• Design current

• Rating factors

• Voltage drop

• Cable size

Why is it important to select an appropriate overcurrent protective device rating (In)?

• To ensure the device is less than the design current

• To prevent circuit overload

• To match the resistance

• To increase the circuit voltage drop.

What happens to the resistance of a cable as it gets warmer?

• It decreases

• It remains the same

• It increases

• It fluctuates

What is the primary concern when a cable retains too much heat?

• Increased flexibility

• Insulation damage

• Reduced length

• Color fading

What does the formula It ≥ In/CaCgCiCf ensure?

• The cable is lightweight

• The cable is cost-effective

• The cable operates safely

• The cable is colorful

How is the design current Ib calculated?

• Power / Voltage

• Current x Resistance

• Voltage / Current

• In / Ca

What is the rating factor for grouping.

• Ca

• Cg

• Ci

• Cf

What is the correct formula used to determine the voltage drop of a circuit.

• It> In/CaCgCiCf

• In

  0.725

• (mV/A/m) x Ib x Length

  1000

• Power

  Voltage

What is the maximum permitted voltage drop for a lighting circuit.

• 6%

• 5%

• 2.5%

• 3%