ELECTRICAL POWER SYSTEM
DESIGN OF HIGH-RISE
RESIDENTIAL/COMMERCIAL
CONDOMINIUM BUILDING
By: Engr. Emiliano G. Marabulas,PEE
The development of the electrical power system
design of high-rise residential and/commercial
condominium building is long and tedious.
However, in this presentation, the development
is in summary form.
It includes the following:
1. Review of the applicable provisions of codes,
laws, and regulations that have jurisdiction over
the electrical Installations.
A.) Philippine Electrical Code Part 2009
Most of the provisions needed are in chapter
1,2,3,4, and article 6.95.
B.) New Electrical Engineering Law
Some of the provisions needed are in sections
26,31,32, and 34.
C.) National Building Code (PD 1096)
D.) Distribution Service Open Access Rules
(DSOAR) of the Energy Regulatory Commission
(ERC)
Some of the provisions needed are those for
connection point, and service drops.
2. Coordination Works
The requirements of design shall be
coordinated with the architect/owner, the
engineers involve the electric utility, and the
government agencies having jurisdiction over
the electrical works.
3. Development of the Design Criteria
These are agreements of the architect/owner
and all engineering disciplines regarding data
other the mandatory requirements of laws,
ordinances, codes, etc.
4. Development of the Design
A.) Notes
It is assumed that the electrical engineer
knows already how to design the electrical
system of a single occupancy residential
building.
B.) Study of the Architectural drawings
This is determination whether the area, space,
location, other requirements are adequate for
the electrical equipment, devices, and
materials to be installed.
C.) Single Line Diagram
This is a drawing which shows all the major
components of the electrical system. The
single line diagram is usually prepared after
the detailed computations. However in this
presentation, it is shown ahead so that we will
be guided where in the particular system the
computation is referred to:
D. Computation (Residential)
1. Sub Service Entrance per Floor
a.) Compute for the total connected load of each
unit
b.) Add the total connected load for each floor
c.) Compute for the current based on the
number of units in each floor and the demand
factor shown in Table 2.20.4.5
d.) Determine the size of subservice entrance
conductors, conduits and protective device
based on the computed current.
2. Main Service Entrance
a.) Add the connected loads of all the units.
b.) Compute for the total current based on the
total number of units and the demand factor
shown in Table 2.20.4.5
c.) Determine the size of the main service
entrance conductors, conduits or busduct and
a protective device based on the computed
current.
E. Computations (Commercial)
Basically the process of computations is
similar to the computations for residential
F. Computations (Administration)
1. Lighting and Convenience Outlets
Basically the process of computations is
similar to the computation for residential
2. Elevators (motor-generator set)
(a) Branch Circuit
a. Size of conductors and conduits
Current=Full load current of the motor (Table
4.30.14.4) multiplied by 140% for intermittent
duty cycle [Table 4.30.2.2(e)] plus 125% of
other continuous load currents.
With this value of current, the size of
conductors and conduits can be determined.
b. Protective Device
The size of the protective device is based on
the full load current multiplied by the
percentage as shown in Table 4.30.4.2 plus
other continuous loads.
(b) Feeder Circuit
a. Size of Conductors and Conduits
Current=Sum of the full load of all the motors
multiplied 140% [Table 4.30.2.2 (e)] multiplied
by demand factor based on the number of
elevator motors (Table 6.20.2.4) plus 125% of
the other continuous loads
With this value of current, the size of
conductors and conduits can be determined
b. Protective Device
The rating of the protective device shall not be
greater than the protective device of the
highest noted elevator motor plus the sum of
the full load current of the remaining motor
plus other continuous loads as section
6.20.7(c).
(b) Overcurrent Protective Device
With the horsepower rating and code letter,
the protective device is determined by the
kilo-volt ampere per horsepower as shown in
Table 4.30.1.7(b)
3. Fire Pump and Pressure Pump
(a) Branch Circuit
The size of conductors and conduits
Current= Full load current multiplied by 125%
with the value of current, the size of
conductors and conduits can be determined
(b) Overcurrent Protective Device
With the horsepower rating and code letter,
the protective device is determined by the
kilo-volt ampere per horsepower as shown in
Table 4.30.1.7(b)
Current= kilo-volt ampere x horsepower rating
horsepower
of the fire pump
divided by [square root of 3 times line to line
voltage (KV)]
With the value of current, the rating of the
protective device can be determined.
(c) Overload Protection
The power circuit shall be provided with
automatic protection against overload
4. Other motors
Other motors shall be considered as ordinary
motors.
5. Main Service Entrance
(a) Size of conductors and conduits
The current shall consider all the demand
loads of the feeders, subfeeders, and branch,
including the application of the 125%.
(b) Overcurrent Protective Device
With the value of current and the rating of the
protective device of the highest rated motor,
the main service entrance protective device
can be determined
G. Computations (Voltage Drop)
With the value of current and the impedance
of each part of the circuits, the voltage drop
can be computed.
H. Computations (Short Circuit Current)
With the value of available short circuit
capacity at the area, the impedance of the
transformer, the impedance of the lines, and
the motor contributions, the short circuit
current at any point can be computed.
I. Computations (Emergency/Standby generator)
The generator shall carry all the loads as per
design criteria. The starting of locked rotor
current shall also be considered.
J. Development of Lighting Protection System
1. Conventional
This is computing the number of air terminals
and determining the materials based on
height as per Table 2.90.3.5, grounding
electrodes, and others to complete the system
2. Enhanced
Enhanced lightning protection system ma be
used provided it is approved by the authority
having jurisdiction or listed by an organization
that is also approved
K. Preparation of all necessary documents
With all of the above. The plans, single line
diagram, specifications, and other documents
as required by PEC 1 2009 can be prepared.
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