Which devices form part of the safety principle in electrical services?

Earthing, fuses, MCB and RCD/ELCB

Which is part of economy and simple design?

Short runs, balanced loads on phases and voltage drop not more than 3-5%

Long runs and unbalanced phases

Single circuit for the whole building

Where should the distribution board and switches be placed?

DB at an accessible central location; switches at about 1.2-1.4 m height

DB inside a locked ceiling void; switches at 3 m

DB in the bathroom; switches at floor level

DB on the roof; switches at 0.3 m

What does the principle of adequacy require?

Points and wire capacity enough for present and future loads

2070 Chaitra (old course) · 4 marks

Short note: General principles of electrical services

Short answer

The general principles are: ensure safety via earthing and protective devices; provide adequate capacity for present and future loads; design economically with low voltage drop; ensure reliability by separate circuits; make systems accessible for maintenance; follow standards; and maintain neat appearance with concealed wiring where possible.

Write a short note on the general principles of electrical services.

Electrical services in a building supply power for lighting, ventilation, appliances, communication and lifts. The general principles are:

Safety: protect people and property from shock and fire (earthing, fuses, MCB, RCD/ELCB).
Adequacy: the number of points, capacity of wires and loads must be enough for present and future use.
Economy and simple design: short runs, balanced loads on phases, minimum voltage drop (not more than 3-5%).
Reliability and continuity: separate circuits for lighting (5 A) and power (15 A); a fault on one circuit should not stop others.
Accessibility: distribution board at an accessible central location; switches at about 1.2-1.4 m height.
Standards: follow the Nepal Electricity rules and standard (NBC / IS 732 / IEC); use ISI/NS marked materials.
Appearance and flexibility: concealed wiring where possible; provision for extension; good lighting levels.

✓ Answer checked by Claude Opus 5.5 (high effort)

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