Practise for the 2391 inspection and testing exams.

Try 8 inspection and testing questions

Real questions from electriQual on continuity, readings, test instruments and what to retest after a fault. Pick your answer, then open it to check.

1. from "Why continuity is first"

   What do the R1+R2 readings get used for later?

   1. AThe insulation resistance reading
   2. BThe RCD trip time
   3. CThe expected Zs for that circuit
   4. DThe PFC at the origin
   Show the answer

   C. The expected Zs for that circuit

   Your R1+R2 figures feed straight into the Zs figures later.

2. from "Why continuity is first"

   What does ring continuity actually prove?

   1. AThat the ring is a complete ring, not broken or crossed over
   2. BThat the insulation is sound
   3. CThat polarity is right at every socket
   4. DThat the RCD will trip
   Show the answer

   A. That the ring is a complete ring, not broken or crossed over

   Ring continuity proves the ring is actually a ring before you judge anything else.

3. from "Things that distort a reading"

   R1+R2 on a radial feeding a bathroom was tested twice. Which is the circuit's own R1+R2?

   R1+R2 on a bathroom radial

   Supplementary bonding	Reading (Ω)
   Connected	0.06
   Disconnected	0.45

   The installation was isolated before the bonding was disconnected.

   1. A0.06 Ω, with the bonding connected
   2. B0.26 Ω, the average of the two
   3. CNeither, the bonding has to stay connected for a valid reading
   4. D0.45 Ω, with the bonding disconnected
   Show the answer

   D. 0.45 Ω, with the bonding disconnected

   Bonded metal pipework is the usual source of a parallel earth path, and a parallel path takes some of the test current and pulls the reading down. Disconnecting the supplementary bonding gives you the true value, 0.45 Ω. It is reconnected afterwards.

4. from "When a test fails"

   A test fails part way through a sequence. Once the fault is rectified, what has to be retested?

   1. AThe failed test only
   2. BThe failed test and any earlier test the fault could have affected
   3. CThe whole sequence from the beginning
   4. DOnly the tests that come after the failed one
   Show the answer

   B. The failed test and any earlier test the fault could have affected

   The failed test is carried out again, and so is any earlier test the fault could have affected.

5. from "The instrument for each test"

   Installation test instruments are built to which standard series?

   1. ABS EN 61557
   2. BBS 7671
   3. CBS EN 60898
   4. DBS 1363
   Show the answer

   A. BS EN 61557

   All of these instruments are covered by the BS EN 61557 series.

6. from "Instrument calibration"

   A tester is dropped from a step ladder three months after its last calibration. What should happen to it?

   1. AIt can be used until its annual calibration falls due
   2. BIt only needs a spot check against a known resistance
   3. CIt goes for calibration before it is relied on again
   4. DIt can be used provided the readings look sensible
   Show the answer

   C. It goes for calibration before it is relied on again

   An instrument that has been dropped goes back for calibration, whatever the date says.

7. from "Instrument calibration"

   What is the legal status of a twelve month calibration interval?

   1. AIt is required by the Electricity at Work Regulations
   2. BIt is set out in BS 7671
   3. CIt is required only for instruments used on certification work
   4. DIt is the accepted industry baseline rather than a stated legal interval
   Show the answer

   D. It is the accepted industry baseline rather than a stated legal interval

   Annual is the baseline, but no regulation names twelve months as the rule.

8. from "The earth fault loop path"

   Where does the earth fault loop start and finish?

   1. AThe consumer unit
   2. BThe transformer winding
   3. CThe main earthing terminal
   4. DThe earth electrode
   Show the answer

   B. The transformer winding

   The loop always starts and finishes at the transformer winding.