Cable Selection

Sample questions

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These sample questions are practice material and have not yet been reviewed by a qualified electrician. They are for revision only — working to BS 7671 on site is never decided by a quiz.

1. Q1.Which of these does NOT reduce a cable's current-carrying capacity?

   • High ambient temperature
   • Grouping with other loaded circuits
   • Thermal insulation around the cable
   • The colour of the cable clips

2. Q2.A cable comfortably carries its load current. Why can a very long run still be a problem?

   • Long runs are not permitted
   • Voltage drop grows with length
   • Current increases with length
   • The cable colours change over distance

3. Q3.A cable is surrounded by loft insulation for part of its run. What happens to its effective rating?

   • It increases
   • It stays the same
   • It is reduced
   • It doubles

4. Q4.Which document sets the voltage-drop limits used when designing UK installations?

   • The property deeds
   • BS 7671
   • The electricity bill
   • GS38