- 2068 Jestha (old course) · 8 marks
Types of electric wiring system compared
Short answer
Common wiring systems include cleat (temporary, lowest cost, poor protection), casing-capping (moderate), batten (low cost, neat, fair protection), lead-sheathed (high cost, good moisture/mechanical), and conduit (highest cost, best mechanical/fire/moisture protection, long life, easy rewiring). Conduit is preferred for permanent installations, batten for dry houses, cleat only for temporary works.
Explain the various types of electric wiring system. Compare them on the basis of cost, life, maintenance and protection against mechanical injury, fire and moisture.
An electric wiring system is the method of running insulated conductors from the distribution board to the points (lights, fans, sockets) in a building. The common types are:
- Cleat wiring: PVC or VIR cables are held on porcelain/plastic cleats screwed to walls and ceilings. Cheap and quick; used for temporary installations (exhibitions, construction sites). Untidy and unprotected.
- Casing and capping (wooden) wiring: cables run inside a wooden casing with grooves, covered by a wooden capping. Older method; now replaced by PVC casing (PVC channel) wiring, which is cheaper and resists moisture better.
- Batten (TRS/CTS) wiring: tough-rubber-sheathed or PVC-sheathed cables are fixed on a straight teak-wood batten with brass/aluminium link clips. Neat and cheap; used in residences and offices for indoor dry places.
- Lead-sheathed (metal-sheathed) wiring: cables with an outer lead/aluminium sheath fixed on battens with link clips; the sheath is earthed. Good mechanical and moisture protection but costly and the sheath can corrode.
- Conduit wiring: PVC cables are drawn through steel or PVC conduit pipes.
- Surface conduit: pipes fixed on the wall surface with saddles (factories, workshops).
- Concealed conduit: pipes buried in walls/slabs during construction (modern buildings). Best appearance and protection; rewiring is easy by pulling wires through the pipe.
Comparison
| Basis | Cleat | Casing–capping | Batten (TRS/PVC) | Lead sheathed | Conduit (steel/PVC) |
|---|---|---|---|---|---|
| Cost | Lowest | Low–medium | Low | High | Highest |
| Life | Short (temporary) | 10–15 years | 15–20 years | 20–25 years | Longest (30+ years) |
| Maintenance | Easy but frequent | Termites, damp attack; moderate | Easy | Low | Lowest; easy rewiring |
| Mechanical injury | Very poor protection | Fair | Fair | Good | Excellent |
| Fire risk | Poor | Poor (wood burns) | Fair | Good | Excellent (steel conduit) |
| Moisture | Poor | Poor (wood absorbs) | Fair (sheath resists) | Good | Excellent if sealed |
| Appearance | Untidy | Fair | Neat | Neat | Best (concealed) |
| Typical use | Temporary works | Old dry buildings | Houses, offices | Damp places | Factories, modern buildings |
Choice: concealed PVC conduit wiring for modern residential and commercial buildings; surface steel conduit or armoured cable in factories with risk of mechanical damage and fire; cleat wiring only for temporary work.
✓ Answer checked by Claude Opus 5.5 (high effort)
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