The document outlines principles of estimating for electrical works, focusing on installation types, system components, and safety measures. It emphasizes the importance of accurate measurement for cost control, detailing various factors affecting material and labor costs. Additionally, it provides guidelines for lighting system design and considerations for electrical installations.

1. BAQS 3290
Principles of Estimating for Building
Services and External Works
1
Topic: Electrical Works

2. OUTLINE
2
• Purpose of M & E Measurement
• Electrical Installations and Main
Components
• Electrical System
• Lighting System
• Domestic Distribution
• Wiring System
• Fittings and Accessories
• Cost Factors – Materials
• Cost Factors - Labour

3. Purpose Of M & E Measurement
3
 To determine elements and components
involved in M & E works
 To estimate with relation to SMM2
 To protect the interest of the client and the
contractor
 A tool for cost control in mechanical and
electrical services.
 To minimize future disagreements

4. Electrical Installations and
Main Components
4

5. Types of electrical works
installation
5

6. Single and Three Phase Theory
6

7. Main Components Electrical
Distribution
7

8. Electrical Distribution in Building
8

9. Main Components Electrical
Installations
9

10. Electrical System
10
• Protection against electric shock
– designed to prevent persons and livestock from
direct contact with live parts of the installation
– preventing a current from passing through the
body of the person or livestock or
– alternatively, by limiting the current which can
pass through the body to a safe value
– automatic disconnection of the supply in a
determined time

11. Electrical System
11
• Protection against thermal effects
– electrical equipment shall not become so hot as
to present a risk of burns to persons or livestock.
– electrical installation shall not pose a risk of
ignition of flammable materials due to high
temperature caused by the electric.

12. Electrical System
12
• Protection against overcurrent
– excessive temperatures or high electromechanical
stresses maybe produced that can cause injury to
persons or livestock and damage to property
• disconnect an overcurrent situation; and
• limit the maximum overcurrent to a safe value and
duration.

13. Electrical System
13
• Erection and initial verification of electrical
installation
– good workmanship carried out by qualified
personnel using proper materials
– identification of conductors, reliable electrical
connections and measures taken to eliminate risk
of fire

14. Electrical System
14
• Division of installation
– divided into several circuits to avoid danger
and minimise inconvenience
– in the event of an electrical fault it
facilitates safe investigation and testing

15. Electrical System
15

16. Electrical System
16
• Protection against direct contact:
• Insulating the live parts
– covering the live parts with insulation
• Use of barriers or enclosures
• Placing out of reach
• Earthing
• Combustible constructional materials
– cause a fire to the walls, floors and ceilings

17. Electrical System
17
• Fire propagating structures
– some structures may facilitate the spread of fires
– recommended to install fire detectors
• Protection against overheating
– ensure that the required airflow be established before
the heating elements are activated
– when the air flow is stopped, the heating element
shall be stopped
– two temperature limiting devices, independent of
each other, shall be installed to prevent permissible
temperatures from being exceeded

18. Electrical System
18
• Wiring system
– an assembly consisting of cables, busbars or cable
trunkings and parts, which secure, support or
enclose them
– components including cables and wiring
accessories shall be installed at temperatures
within its limits

19. Electrical System
19
• Wiring system
– protected from heat sources by:
a) shielding;
b) placing sufficiently far from heat source;
c) selecting a wiring system rated for the effects of the
heat source; and
d) local reinforcement or substitution of insulating
material.
– Examples of heat sources are hot water systems
or steam pipes; manufacturing process; and the
sun.

20. Electrical System
20
• Wiring system
– not to be damaged by water
• make provisions for the water to escape
– not to be damaged by solid foreign objects
• dusty environment
– corrosive or polluting environment
• protected or made from materials resistant to these
detrimental substances

21. Electrical System
21
• Wiring system
– minimise the damage due to mechanical stress,
e.g. install a steel plate to protect the wiring
system by impact
– care shall be taken that the cable connections are
not compromised by vibration
• use of cables with a flexible core

22. Electrical System
22
• Wiring system
– care shall be taken that the cable connections are
not compromised by vibration
• use of flexible conduit
• use of flexible trunking

23. Electrical System
23
Socket Wiring system

24. Electrical System
24
Single Phase
Source: Suruhanjaya Tenaga, A Guidline for Electrical Wiring for Residential (2014)

25. Electrical System
25
Three Phase
Source: Suruhanjaya Tenaga, A
Guidline for Electrical Wiring
for Residential (2014)

26. Lighting System
26
• Lighting designers must consider eight key factors
when specifying lighting systems
– The owner's project requirements (OPR) that include
project costs and schedule
– The basis of design (BOD)
– Codes and standards, including energy guidelines
– Sustainability certifications (GBI, etc.)
– Recommended lighting levels
– Lifecycle costs
– Safety and security
– Maintenance and warranty

27. Lighting System
27
• building occupants do not necessarily want
LEDs or wireless control—they want to be
comfortably seeing what they are doing
• enhancing the architecture,
• integrating with the available daylight,
• minimizing building energy use, and
• aligning with the overall construction process
and budget

28. Lighting System
28
• illuminate the architectural forms and
surfaces

29. Lighting System
29
• criteria for both quantity and quality of light
depend on the type of task performed in each
space and work area

30. Lighting System
30
• interior design choices, such as surface
finishes, can have a dramatic impact on the
lighting system and how much light is
required to make a space feel bright
• visual elements of lighting equipment must
also coordinate with the interior design

31. Lighting System
31

32. Lighting System
32

33. Compound Lighting
33

34. Compound Lighting
34

35. Taking-off List for Electrical
Installations
35

36. 36
 Internal – domestic
 Distribution board

37. 37
 Internal – domestic
 Sub-circuit
 DB to sub DB
 Final sub-circuit
 Sub DB to fittings

38. 38
Distribution Boards

39. 39
 Trunking
 Conduit

40. 40

41. 41
Conduits

42. 42
 Power outlet
 Switches

43. 43
Switches,
Socket and
points

44. 44

45. Taking-off List for Electrical
Installations (cont’d)
45

46. Electrical System
46
• Manufactured equipment and fittings:
– Switches
– Socket outlets
– Cable outlets
– Light fittings
• Connected by
– Electrical cables of various sizes

47. Electrical System
47
• Labour:
– Delivery
– Storing
– Setting or supporting during installation
– Connecting equipment, outlets and fittings

48. Cost Factors - Materials
48
• Wiring
• Trunking/conduit
• Installation route
– In wall – chased
– In celing
– In floor
• Fittings

49. Cost Factors - Materials
49
Wiring – Factors that affect the cost of wiring
Type of the building
Size of the building
Arrangement of the buildings
Materials used in the construction of the
building
Building frame (Steel, masonry, concrete)

50. Cost Factors - Materials
50
Wiring – Factors that affect the cost of wiring
per outlet
Length run between outlet
Kind of installation
Size of wire required
Type of conduit used
Materials
Labour

51. Cost Factors - Materials
51
Wiring – Item to be included in the Cost of
Wiring
Service Wire
Meter Box
Switch Box
Conduit
Wire
Switches
Sundries Supplies (where necessary)

52. 52

53. 53

54. 54

55. Cost Factors - Labour
55
Labour Factors
There are three (3) approach to estimate labour
cost for wiring:
 Cost per outlet
 Percentage from cost of materials
 Time required to perform the task/ labour
constant

56. Cost Factors - Labour
56
Labour Factors
 Cost per outlet

57. Cost Factors - Labour
57
Labour Factors
 Time required to perform the task
Normally requires two labour, an
electrician and a helper (semi-skilled).
Labour-hour

58. Estimating for Electrical
Works
58
 Materials
 Fittings and Accessories
 Cables (times 2 – thru and for/ or sometimes 3
depending on the specification)
 Conduits
 Total of all material cost to add wastages
 Labour Cost
 Testing and Commissioning
 Overhead and profit