This question was popular among the candidates and their performance was good.
In part (a), majority of the candidates were able to explain preventive and corrective maintenance.
In part (b), majority of the candidates were able to list procedures for preventive maintenance of electrical machines and equipment.
In part (c), majority of the candidates were able to give the uses of the conduit boxes listed.
In part (d), majority of the candidates were able to illustrate using diagram how a point of light could be controlled independently by two 2 –way switch. However, some of the candidates could not answer the question correctly.
Part (e) of this question was fairly answered by majority of the candidates.
The expected answers include:
1(a) (i) Preventive maintenance is a form of regular maintenance carried out on a
(working) machine or equipment to keep it operational / protect it from
complete breakdown.
(ii) Corrective maintenance is the type of maintenance carried out on a faulty/break down machine/device/equipment to put it into use again.
(b) - planning;
- inspection;
- cleaning;
- tightening;
- lubricating/oiling/greasing;
- trouble shooting;
- covering.
(c) (i) It is used at the end of a conduit / lamp holder base
(ii) It is used to branch/link conduit in any four different directions
(iii) It is used to branch/link conduit in any three different directions
(iv) It is used to branch/link conduit in any two different directions
(v) It is used for lighting/ceiling fans final sub-circuit
(d)
(e) (i) Single phasing is the effect produced when an open circuit occurs on
one of the lines or phase conductors supplying a 3-phase motor
(ii) Voltage operated (earth leakage circuit breaker)
Current operated (earth leakage circuit breaker)
(iii) - to prevent earth leakage
- to prevent electric shock
- to prevent excess current
- to prevent low voltage
- to prevent damage by fire
- to maintain continuity of supply
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