Electrical System Design
and Load Calculations
as per
Philippine Electrical Code
PREPARED AND PRESENTED BY:
`
I I E E - S Q C 1 s t S t u d e n t s Te c h n i c a l We b i n a r s
March 26, 2021, via Zoom Video Conferencing
INTRODUCTION
PEC 2017
OV E RV I E W
How to use PEC
• Depending on Work Experience
• Understand the technical terms
LIVEPARTS?” DEADFRONT?
• Arrangement of PEC
Changes of PEC 2017
• Major Revision from 2009
• One Volume
• Letter Page Format
consisting two columns
• PEC tables is now
Chapter 10
• Based of NEC 2017
Layout of PEC
Chapter -1 General
Chapter -2 Wiring and Protection
Chapter -3 Wiring Methods and Materials
•
Applies Generally to
Electrical Installations
• the scope of this book
all
Chapter -4 Equipment for General Use
•
Supplements or modifies chapter 1 to 4
•
Specific Rules (Motion Picture Projectors,
Recreational Vehicles, Cranes and Hoists, XRay Equipment, etc.)
Chapter -5 Special Occupancies
Chapter -6 Special Equipment
Chapter -7 Special Conditions
Chapter -8 Communication Systems
Radio, TV Equipment and Cable TV Systems
Chapter -9 Watercrafts
Generally, for waterborne unit
Chapter -10 Tables
Physical Properties
Layout of PEC(cont’d)
2. Articles- is a specific subject, such as:
• Grounding
• Fixtures
• Services
• Motors
• Feeders
• Appliances
• Branch Circuits
• AC, etc.
3. Parts- when an article is sufficiently large, the article is subdivided
into parts. The parts break down the main subject of the article into
organized groups of information.
For example, Article 2.30 contains eight parts, such as Part A-General,
Part B-Overhead Service Conductors, and Part H-Services Exceeding
600 Volts, Nominal.
PEC Introduction: Layout of PEC
4. Sections and Tables.
The actual PEC Code rule is called a section and is identified with
numbers and letters.
A Code section may be broken down into subsections (by letters in
parentheses) and each subsection may be broken down further by
numbers in parentheses.
For example, the section that requires all receptacles in a dwelling unit
bathroom to be GFCI protected is Section 2.10.8(a)(1).
Many Code sections contain tables, which are a systematic list of Code
rules in an orderly arrangement.
For Example, Table 3.10.1.16 contains the ampacity of conductors.
PEC Introduction: Layout of PEC
5. Exceptions- are in italic type and provide an alternate choice to a specific rule.
Two types of exceptions:
• Mandatory- uses the words shall or shall not in the wording.
• Permissible-uses such words as shall be permitted, this means that it's okay to do it
in this way.
6. Fine Print Notes (FPN)
• Are explanatory material, not Code rules.
• Attempt to clarify a rule or give assistance, but they are not a Code requirement.
For example,
FPN No. 4 of Section 2.10.19(a) states that the voltage drop for branch circuits should
not exceed 3% of the circuit voltage. This is not a Code requirement but only a
suggestion
PEC Introduction: Layout of PEC
7. Definitions - are listed in Article 1.1 and throughout the PEC. In general,
• the definitions listed in Article 1.1 apply to more than one Code article
• Definitions at the beginning of a specific article apply to that article only.
• Definitions in a part of an article apply only to that part, and definitions in a specific
Code section only apply to that section.
PEC Introduction: Layout of PEC
Now that you know basically
what’s in each of the
CHAPTERS:
It’s time to go through the
related ARTICLES for our topic
Chapter 1
Article 1.0 Introduction
1.0.1.1 Purpose
A) PRACTICAL SAFEGUARDING of persons
hazards arising from the use of electricity.
✓ Good Quality of Design
✓ Good Workmanship in
Electrical Construction
Chapter 1
and
property
from
✓ Approved Electrical
Equipment and Materials
Chapter 1
For the safety of persons
and property from hazard
arising from the use of
electricity
Chapter 1
• Minimum requirements
• Compliance
and
proper
maintenance is required.
• Consideration
for
future
expansion
Chapter 1
(cont’d)
COMPLIANCE TO THE PEC WILL ENSURE SAFETY AND PREVENT
ELECTRICAL FIRES???
✓ Energy management, maintenance, and power quality
issues aren’t within the scope of the Code.
IIEE-State of Qatar Chapter
In case of conflicting interpretation/s
1.
PEC Part 1 Committee
2.
For Final Interpretation/s
Board
of
Electrical
Engineering
IIEE-State of Qatar Chapter
HON. FRANCIS V. MAPILE
HON. JAIME V. MENDOZA
Conduit required to be
installed for future
Space for future
expansion
IIEE-State of Qatar Chapter
IIEE-State of Qatar Chapter
Let’s discussed some
important
definitions
related to our discussion.
OCPD
Conductors
[;
[;
[;
Loads
Therefore: Branch Circuits is consist of
1. OCPD (CB or Fuses)
2. Conductors (Wires or Cables)
3. Loads (can be motors, lights, small power, etc.)
M
Lightings if used for 3 hours or more
Water Heater
For non dwelling unit such as commercial, industrial, etc all loads are considered
continuous loads except for GENERAL PURPOSE AND APPLIANCE BRANCH CIRCUIT
Let’s do wiring design
examples to illustrate
the application of some
of the provisions of
this Code.
PROJECT NO. 1
S M A L L P OW E R L A YO U T
2.10.3.3
STORAGE
T&B
MAID’S
ROOM
T&B
DINING
AREA
LAUNDRY
AREA
KITCHEN
AREA
LIVING
AREA
STORAGE
2.7m
S M A L L P OW E R L A YO U T
2.10.3.3
STORAGE
T&B
MAID’S
ROOM
T&B
DINING
AREA
LAUNDRY
AREA
KITCHEN
AREA
LIVING
AREA
STORAGE
S M A L L P OW E R L A YO U T
2.10.3.3
STORAGE
T&B
MAID’S
ROOM
T&B
DINING
AREA
LAUNDRY
AREA
KITCHEN
AREA
LIVING
AREA
STORAGE
S M A L L P OW E R L A YO U T
2.10.3.3
G
G
STORAGE
T&B
G
G
T&B
MAID’S
ROOM
G
DINING
AREA
G
G KITCHEN
LAUNDRY
AREA
G
G
G
AREA
G
G
G
LIVING
AREA
STORAGE
G
G
G
S M A L L P OW E R L A YO U T
G
W
MAID’S
ROOM
G
G
T&B
DINING
AREA
G
G KITCHEN
W
G
LAUNDRY
AREA W
G
G
AREA
G
STORAGE
T&B
G
W
W
G
G
W
G
W
LIVING
AREA
STORAGE
W
G
W
W
G
G
W
S M A L L P OW E R L A YO U T
2.10.3.(A)
W
G
G
<0.6m
≥0.6m
P
RAILINGS
W
G
W
P
<0.6m
G
W
N O N - DW E L L I N G U N I T
MEETING
ROOM
FOR MEETING ROOMS
• SPACING OF RECEPTACLE OUTLETS
SAME WITH THE REQUIREMENTS OF
DWELLING UNITS (2.10.3.22)
• WITH 3.7 m width and has a floor area of
20m2 shall have at least one floor outlet
installed not more than 1.8 m from fixed
wall .
OTHER AREAS
• RECEPTACLE OUTLETS LOCATION TO
BE DETERMINED BY DESIGNER/ OWNER
L I G H T I N G L A YO U T
S
S
S
S
S
S
S
S
S
S S
S
S
S
S S SS
L I G H T I N G L A YO U T
S
S
S
S
S
S
S
S
S
S S
Branch Circuit Requirements
G
W
MAID’S
ROOM
G
G
T&B
DINING
AREA
G
G KITCHEN
W
G
LAUNDRY
AREA W
G
G
AREA
G
STORAGE
T&B
G
W
W
G
G
W
G
W
LIVING
AREA
STORAGE
W
G
W
W
G
G
W
Section 2.10.3.3
Branch Circuit Requirements
G
W
MAID’S
ROOM
G
G
T&B
DINING
AREA
G
G KITCHEN
W
G
LAUNDRY
AREA W
G
G
AREA
G
STORAGE
T&B
G
W
W
W
G
G
W
G
W
LIVING
AREA
STORAGE
W
G
W
W
G
G
This section allowing lightings and utilization equipment to
be connected in one branch circuit.
Section 2.10.1.11(C)
Branch Circuit Requirements
G
W
MAID’S
ROOM
G
G
T&B
DINING
AREA
G
G KITCHEN
W
G
LAUNDRY
AREA W
G
G
AREA
G
STORAGE
T&B
G
W
W
G
G
W
G
W
LIVING
AREA
STORAGE
W
G
W
W
G
G
W
Section 2.10.1.11(C)
Conductor Selection Factors
600V
THHN/THWN-2
50mm2
SIZE
CONSIDERING
CORRECTION
FACTORS
VOLTAGE
INSULATION
AMPACITY
In the PEC, generally, rules of application are divided into for
cables 0 to 2000 Volts and for cables over 2000 Volts.
COMMON BUILDING WIRES AND CABLES ARE
▪ No H 60°C insulation rating (such as TW wires & cables)
▪ H 75°C insulation rating (such as THW wires & cables)
▪ HH 90°C insulation rating
Note: as per Table 3.10.16
THHN / THWN-2
▪ -2 Conductor is permitted to be used at a continuous
90ºC operating temperature in a wet or dry location
Insulation Acronym Letter Meaning
H - Stands for Heat Resistant
HH - High Heat
Cable
ampacity
should
W - Wet and Damped Location
match the requirement of
N - Nylon Jacket
the DEMAND LOAD of a
T - Thermoplastic Insulation
circuit.
There are Twenty Six (26) Ampacity Tables on PEC
•
Six (6) for up to 2000 Volts
•
Twenty (20) for more than 2000 Volts
A m p a c i t y Ta b l e
Lifted from PEC 2017 page 174
A m p a c i t y Ta b l e s o n P E C
Fo r E x a m p l e
What if :
More than 3 conductors or
Ambient temperature is 45oC or 15oC
Conductor Sizing to considering
these Factors
•
•
•
•
•
•
•
Compliance with the minimum sizing
of branch circuits,
Conductor bundling (grouping factor),
Ambient temperature,
Equipment Terminal Rating,
Voltage Drop
Short Circuit
Insulation
Equipment Terminal Rating
Consideration were included in
the 10 Most Common Philippine
Electric Code Violations
SECTION 1.10.1.15(c)
TEMP. RATING
TW-60C, THW-75C
& THHN-90C
CB TERMINAL HAS
TEMP RATING
THIS TERMINAL
HAS
TEMP
RATING
ARTICLE 1.10.1.15(C)
Unless
listed
and
marked
otherwise,
conductors must be
sized using the 60◦C of
Table 3.10.2.6(B) (16)
Unless listed and marked
otherwise, conductors must
be sized using the 60◦C of
Table 3.10.2.6
Equipment Over 100A
3.10.2.6(B) (16)
RULES OF PHILIPPINE
ELECTRICAL CODE
FOR SIZING OF
BRANCH CIRCUITS
Section 2.10.2.2
FPN No. 1
There are Twenty Six (26) Ampacity
Tables on PEC
• Six (6) for up to 2000 Volts
• Twenty (20) for more than 2000
Volts
ARTICLE 3.10 Conductors for General Wiring
L e t ’s d o
some
ex e r c i s e s
Section 2.10.2.2(1)
Example:
A branch circuit with continuous load of 16 amperes and
noncontinuous load of 30 amperes.
The conductor must be sized to have an ampacity not less
than
30A + (16A x 1.25) = 50A
According to Table, 14mm2 conductor is suitable, because
it has an ampere rating of 55A, before any conductor
ampacity adjustment and/or correction.
2.10.2.3 Overcurrent Protection
2.50.6.13 Size of Equipment Grounding Conductors.
Applying Branch Circuit Calculation
CKT
NO.
LOAD DESCRIPTION
VOLT-AMP
LOAD
AMPERE
LOAD
WIRE
OCPD
ECG
1
22-Light Outlets at Ground Floor
2200
9.57
2.0
15
2.0
2
26-Light Outlets at Second Floor
2600
11.31
2.0
15
2.0
3
17-Receptacle Outlets at Grd Floor
Note:: Article 2.20.2.5(D) –Luminaire(s) shall be calculated based on the maximum volt-ampere rating
of the equipment and lamps for which the luminaire(s) is rated.
Note:: Article 2.20.2.5(I) –Receptacle Outlets shall be calculated at not less than 180 volt-ampere .
• Branch Circuit #1: 2200 Volt-Amperes Lighting Load
• What size of conductor and overcurrent protection a 1100 Volt-Amperes Lighting Load
required?
•
2200/230 = 9.57 Amps;
9.57 A x 1.25 = 11.96 Amps
• According to Table 3.10.2.6(B) the conductor suitable is 2.0mm2 THHN
• According to Table 2.40.1.6(A) the suitable size is 15 AT,
• Equipment Grounding refer to Table 2.50.6.13 is 2.0mm2 THHN
Applying Branch Circuit Calculation
CKT
NO.
LOAD DESCRIPTION
VOLT-AMP
LOAD
AMPERE
LOAD
WIRE
OCPD
ECG
1
22-Light Outlets at Ground Floor
2200
9.57
2.0
15
2.0
2
26-Light Outlets at Second Floor
2600
11.31
2.0
15
2.0
3
17-Receptacle Outlets at Grd Floor
3060
13.31
2.0
15
2.0
Note:: Article 2.20.2.5(I) –Receptacle Outlets shall be calculated at not less than 180 volt-ampere .
• Branch Circuit #3: 3060 Volt-Amperes Branch Circuit Small Appliance Load
• What size of conductor and overcurrent protection a 3060 Volt-Amperes Branch Circuit
Small Appliance Load required?
•
3060/230 = 13.31 Amps
• Note: Small Appliance Load is not Consider a continuous loads, Hence 13.31 Amperes
for branch circuit 3
• According to Table 3.10.2.6(B) the conductor suitable is 2.0mm2 THHN
• According to Table 2.40.1.6(A) the suitable size is 15 AT
• Equipment Grounding refer to Table 2.50.6.13 is 2.0mm2 THHN
FOR SIZING OF MOTOR AND
AIR-CONDIOTIONING
BRANCH CIRCUIT REFER TO
ARTICLE 4.30 and 4.40
Sizing of Motor Conductor refer to
ampacity table 3.10.2.6(B)
The required ampacity and motor
ratings shall be determined as
specified in 4.30.1.6(A), (B), (C), and
(D).
To determine the Full
Load Current (FLC) – Go
to table 4.30.14.2
FLC is equal to is 52
Amps
Full Load Amperes (FLA)
is equal to 34.9 Amps
FLA vs FLC
FLA is use to size the OVERLOAD PROTECTION
FLC is use to size the CONDUCTOR and SHORT CIRCUIT & GROUND FAULT PROTECTION
FLA – FULL CURRENT BASED ACTUAL
(NAMEPLATE OF MOTOR)
FLC – FULL CURRENT BASED ON CODE
Conductor for a single motor must be sized not less
than 125 percent of the FLC rating in table
4.30.1.6(A) or 4.30.2.2(A) through (G)
This device use purpose is to protect the
motor, the motor equipment, and
conductor against short circuit or ground
faults. But not against overload.
The next size up fuse or circuit breaker is
permitted when the protection device
value determined from table 4.30.4.2
doesn’t correspond with the standard
device rating listed Table 2.40.1.6(A)
•
•
•
•
•
•
•
Step 1:Determine the branch circuit conductor of
2-hp, 230V motor FLC = 12A
12A × 1.25 = 15A
A 2.0mm2 conductor is rated 20A
Step 2: Determine the branch circuit protection
12A × 2.50 = 30A
Step 3: The circuit equipment grounding conductor
must be sized to the 30A overcurrent device —
5.5mm2 [Table 2.50.16], but it’s not required to be
sized larger than the circuit conductors — 14 AWG
[250.16(A)].
What is a hermetic refrigerant motorcompressor? It's a combination consisting of
a compressor and motor enclosed in the
same housing. These have no external shaft
or shaft seals, and the motor operates in the
refrigerant.
Short Circuit and Ground fault protective
device must not be greater that 175% of
equipment load current rating
If you reached the 175% threshold but the
OCPD can’t carry the starting current of the
motor compressor, you can use the next size
larger OCPD. However, this OCPD can’t
exceed 225% of the motor compressor
current rating.
Conductor sized at 125% of compressor rating
A key term to understand is “rated-load
current.” This is the current resulting when
the motor-compressor operates at rated load
and rated voltage.
CKT
NO.
LOAD DESCRIPTION
AMPERE LOAD
WIRE
(mm2 THHN)
13
1.0 Hp Booster Pump
8
2.0
14
1.5 Hp Window Type AC
10
2.0
15
3.0 Hp Split Type AC
17
5.5
16
3.0 Hp Split Type AC
17
5.5
17
1,0 Hp Window Type AC
CIRCUIT
BREAKER
EQPT GROUND
(mm2 THHN)
• Branch Circuit #13:
• Branch Circuit #15:
• 1.0hp, 230V, 1 phase Booster Pump
• 3hp, 230V, 1 phase Split Type AC
• What size branch-circuit THHN conductor • What size branch-circuit THHN conductor
does a 1.0hp, 230V, Booster Pump need ? does a 3hp, 230V, Split Type AC required?
• Referring to Table 430.14.2 (FLC, 1 phase, • Referring to Table 430.14.2 (FLC, 1 phase,
AC),
AC),
• Therefore: 8.0A x 1.25 = 10.0 Amps
• Therefore: 17A x 1.25 = 21.25 Amps
• According to Table 3.10.2.6(B) (16) the
• According to Table 3.10.2.6(B) (16) the
conductor suitable is 2.0mm2 THHN
conductor suitable is 5.5mm2 THHN
CKT
NO.
LOAD DESCRIPTION
AMPERE LOAD
WIRE
(mm2 THHN)
13
1.0 Hp Booster Pump
8
2.0
14
1.5 Hp Window Type AC
10
2.0
15
3.0 Hp Split Type AC
17
5.5
16
3.0 Hp Split Type AC
17
5.5
17
1,0 Hp Window Type AC
8
2.0
CIRCUIT
BREAKER
EQPT GROUND
(mm2 THHN)
• Branch Circuit #14:
• Branch Circuit #13:
• 1.0hp, 230V, 1 phase Booster Pump
• 3hp, 230V, 1 phase Split Type AC
• What size Short Circuit and Ground Fault
• What size branch-circuit THHN conductor
Protection for 1.0hp, 230V, Booster Pump
does a 3hp, 230V, STAC required?
need ?
10A x 2.50 = 25.0 Amps
17 x 1.75 = 29.75
• According to Table 2.40.1.6(A) the suitable
• According to Table 2.40.1.6(A) the suitable
size is 30 AT
size is 30 AT
• Equipment Grounding refer to Section
2.50.6.12(B) is 5.5mm2 THHN, HOWEVER • Equipment Grounding refer to Section
2.50.6.12(B) is 5.5mm2 THHN
• GROUNDING CANT BE HIGHER, HENCE
USE 2.0mm2
BRANCH CIRCUIT SIZING FOR
• Branch Circuit #18:
• 230V, 1ph, 5.0kW Water Heater
• What size branch-circuit THHN conductor 230V,
1ph, 5kW Water Heater need?
•
P =VI ;
I = P/V
I = 5000/ 230 = 21.74 Amps
• Therefore: 21.74 A x 1.25 = 27.17 Amps
• According to Table 3.10.2.6(B) (16) the conductor
suitable is 5.5mm2 THHN
CKT
NO.
18
LOAD DESCRIPTION
5.0 kW Water Heater
AMPERE LOAD
WIRE
(mm2 THHN)
21.74
5.5
CIRCUIT
BREAKER
EQPT GROUND
(mm2 THHN)
The overcurrent device can’t exceed 150%
of the rated current, but next size can be
used if the appliance rating at 150%
doesn’t correspond to a standard size
overcurrent device.
• Branch Circuit #18:
• 230V, 1ph, 5kW Water Heater
• What size branch-circuit overcurrent protective
device for 230V, 1ph, 4.5kW Water Heater need?
•
P =VI ;
I = P/V
I = 5000/ 230 = 21.74 Amps
• Therefore: 21.74 A x 1.50 = 32.61 Amps
• According to Table 2.40.1.6(A) the suitable size is
40 AT
CKT
NO.
18
LOAD DESCRIPTION
5kW Water Heater
AMPERE LOAD
WIRE
(mm2 THHN)
CIRCUIT
BREAKER
EQPT GROUND
(mm2 THHN)
21.74
5.5
40
5.5
BRANCH CIRCUIT SIZING FOR
2.20.2.9 Maximum Loads
CKT
NO.
19
LOAD DESCRIPTION
8.0 kW Electric Range
AMPERE LOAD
WIRE
(mm2 THHN)
CIRCUIT
BREAKER
EQPT GROUND
(mm2 THHN)
27.83
• Branch Circuit #14: 230V, 1ph, 8.0 kW Electric Range
• What size branch-circuit overcurrent protective device and conductor for 230V, 1ph, 230V, 1ph,
8.0kW Electric Range required?
• Refer to Table 2.20.3.16, including note 4
•
8000x 80% = 6400 W (Column B @ 80%)
I = 6400/ 230 = 27.83 Amps
Hence, 27.83 x 1.25 = 34.78
• According to Table 2.40.1.6(A) the suitable size is 40 AT
• According to Table 3.10.2.6(B) (16) the conductor suitable is 8.0 mm2 THHN
• Equipment Grounding refer to Table 2.50.6.13, is 5.5 mm2 THHN
LOAD SCHEDULE
Design Analysis/ Load Computation
AREA : 224.00 SQ.M.
❑ AIR-CONDITIONING LOADS (See Section 2.20.4.3) :
•
1 UNIT - 1.0 HP, 230V, 1∅ WINDOW TYPE A/C @ 8 FLC. …….…………………………………………...…. 1,840.00 VA
•
1 UNIT - 1.5 HP, 230V, 1∅ SPLIT TYPE ACCU @ 12FLC…………………………………………………….. 2,760.00 VA
•
2 UNITS - 3.0 HP, 230V, 1∅ SPLIT TYPE ACCU @ 17 FLC......................................................................... 7, 820.00 VA
❑ OTHER LOADS :
•
LIGHTING LOAD @ 24 VA/SQ.M. (224.00 x 24) ………..………………………...............…… ,5,376.00 VA.
•
SMALL APPLIANCE LOAD : 5 - 20A CKTS @ 1500 VA/CKT……………….……………..…... 7,500.00 VA
•
LAUNDRY CIRCUITS : 1 - 20A CKTS @ 1500 VA/CKT……................................................. 1,500.00 VA
▪
1 UNIT - 8.0kVA., 230V, 1∅ RANGE @ NAME PLATE RATING.. (8,000.00 VA x 0.80 D.F.).. 6,400.00 VA
•
•
1 UNIT - 5.0KVA, 230V, 1∅ WATER HEATER ………………………………………..……........ 5,000.00 VA
1 UNIT - 5.0KVA, 230V, 1∅ CLOTHES DRYER ……………………………………..……........ 5,000.00 VA
•
1 UNIT - 1.5 HP, 230V, 1∅ BOOSTER PUMP @ 12FLC……………..……………………….. 2,760.00 VA
SUB TOTAL ……………………………….…………….………..… 17, 680.00 VA
Application of Demand Factors: [See Section 2.20.4.3(C)]
First 10 000 volt-amperes@ 100% D.F. ………………………….……………………………………………………. 10, 000.00 VA
Remainder@ 40% D.F (23,536.00x 0.40) . ………………………………………….……………….………….…….
9, 414.40 VA
TOTAL NET COMPUTED LOAD ……………..………………………………..…..… 31, 834.40 VA
Design Analysis/ Load Computation (cont’d)
TOTAL ………………………… 31, 834.40 VA
I=
31,834.00
+ 17.00 (25%) = 142.66 Amperes
230
• SERVICE ENTRACE CONDUCTOR:
142.66 A x 1.25 = 178.32 Amperes
for Conductor more than 100A use 75% Column, unless listed and marked (terminal rating
consideration)….
According to Table 100mm2 conductor (THW or THHN) is suitable, because it has an
ampere rating of 185A at 75ºC
THEREFORE:
USE: 2 #185mm2 THW & 1 #14mm2 TW
200A, 2P 250V. CB AS MAIN.
V O L TA G E D R O P
C A L C U L AT I O N S
Exer cises
NEC Table 8
What is voltage drop of a 179A, 1ph at 230 volts 0.85pf
with conductor 100mm2 at length of 70 meters
3. PEC FORMULA TO TABLE 10.1.1.9
For Single Phase
VD = 2 x I (R cosθ + X Sin θ) x L/1000
Where:
R-Resistance of Cables
X -Reactance of Cables
For 3 phase
I- Current
VD = 1.732 x I (R cosθ + X Sin θ) x L/1000
L- Length of Conductor in ft.
For the purpose of calculating voltage drop within a cable, the table below
gives the reactance and resistance values for Copper and Aluminum cables,
however this is for 3 phase, it is advisable that the designer to request to
wire and cable supplier for the table.
VO LTA G E D R O P M E T H O D O F
C A L C U L AT I O N
Applying the previous problem:
R (as per table 10.1.1.90) = 0.51
θ = Acos(0.85) = 31.79 deg
X (as per table 10.1.1.90) = 0.063
Sin θ = 0.527
For 3 phase
VD = 1.732 x 179 x [(0.51)(0.85) + (0.063)(0.527)] x 230/1000
VD = 2.36 Volts
2.36
% VD =
x 100 = 1.03 %
230
VO LTA G E D R O P M E T H O D O F
C A L C U L AT I O N
3. PEC FORMULA TO TABLE 10.1.1.9
For Single Phase
VD = 2 x I x Z x L/ 1000
VD = 2 x I (R cosθ + X Sin θ) x L/1000
For 3 phase
VD = 1.732 x I x Z x L/1000
VD = 1.732 x I (R cosθ + X Sin θ) x L/1000
Voltage Drops
To ensure efficiency of operation, Article 2.10.2.1 shall be
the basis of conductor minimum ampacity and size, in a way
of preventing voltage drop exceeding 3 percent at the
farthest outlet of power, heating and lighting loads or
combination of such loads. And a maximum Voltage drop of
not exceeding 5 percent to the farthest outlet on both
feeders and branch circuits (Article 2.10.2.1 (a) FPN No. 4)
PEC RULES IN
GENERATOR
SIZING
GENERATOR SIZING
• CALCULATE THE GENERATOR SIZE FOR
• LOAD = 31,834.40 VA
• FUTURE OF 20%
kVA Total = MDL + 20% SPARE LOAD
= 31,832 (1.20) = 38,201VA
THEREFORE USE
Use minimum of 40kW, 230VOLTS,
1PHASE 60Hz PF STANDBY DIESEL
GENERATOR
GENERATOR SIZING (CONTD)
GENERATOR CONDUCTOR
MINIMUM AMPACITY = 115% x RATED CURRENT
GENERATOR CAPACITY 40kW, 230 VOLTS, 60Hz
= 115 % X [ 40000 / 230] = 200 AMPS
referring to Table 3.10.2.6 (B)(3)(a), 100mm2 rated 220A
GENERATOR SIZING (CONTD)
GENERATOR OVERCURRENT PROTECTIVE DEVICE
GENERATOR CAPACITY 40kW, 230 VOLTS, 60Hz
MAXIMUM AMPACITY : = 40 / 2300 = 173.91AMPS
According to Table 2.40.1.6(A) the suitable size is 170 AT
Equipment Grounding refer to Table 2.50.6.13 is 14 mm2,
PEC 2017
Rules on
Fire Pump
Article 6.95-Fire PumpsIs geared toward protecting
the facility and people.
Keeping that fire pump
running is mandatory.
PEC 2017 Rules on Fire Pump: Introduction
Now,
What is the Rules of
PEC 2017
for Fire Pump
PEC 2017 Rules on Fire Pump: Introduction
Fire Pump Conductor Size
6.95.1.6 (B) Conductor Size.
(1) Fire Pump Motors and Other Equipment.
Conductors supplying a fire pump motor(s), pressure maintenance
pumps, and associated fire pump accessory equipment shall have a
rating not less than 125 percent of the sum of the fire pump
motor(s) and pressure maintenance motor(s) full load current(s),
and 100 percent of the associated fire pump accessory equipment.
(2) Fire Pump Motors Only. Conductors supplying only a fire pump
motor shall have a minimum ampacity in accordance with 4.30.2.2
and shall comply with the voltage drop requirements in 6.95.1.7.
PEC 2017 Rules on Fire Pump
Fire Pump Accpetable Voltage Drop
6.95.1.17 Voltage Drop.
(A) Starting. The voltage at the fire pump controller line
terminals shall not drop more than 15 percent below normal (
controller-rated voltage) under motor
starting conditions.
Exception: This limitation shall not apply for emergency run
mechanical starting. [20:9.4.2]
(B) Running. The voltage at the load terminals of the fire pump
controller shall not drop more than 5 percent below the voltage
rating of the motor connected to those terminals when the
motor is operating at 115 percent of the full-load current rating
of the
motor.
PEC 2017 Rules on Fire Pump
Exercise #6. What size of conductor at 75°C
terminal rating does a 75-hp, 400V, 3Ø Fire Pump,
The fire pump motor controller is 60 meter from
the service ?
(a) 50mm2
(b) 65mm2
(c) 38mm2
(d) none of these
Referring to Table 430.14.4 (FLC, 3phase,
AC), 128 A
• Refer to Table 3.10.2.6(B) (16) the conductor suitable
is 50 mm2 IS 140A
• As per Section 4.30.5 is
Answer: (A) 50mm2, rated 140A
Fire Pump Overcurrent Device Selection.
6.95.1.4 (B) (2) Overcurrent Device Selection.
Overcurrent devices shall comply with 6.95. l .4(B)(2)(a) or (b).
(a) Individual Sources. Overcurrent protection for individual sources shall
comply with 6.95. 1 .4(B)(2)(a)(1) or (2).
(1) Overcurrent protective device( s) shall be rated to carry indefinitely the
sum of the locked-rotor current of the largest fire pump motor and the
pressure maintenance pump motor(s) and the full-load current of all of the
other pump motors and associated fire pump accessory equipment when
connected to this
power supply. Where the locked-rotor current value does not correspond to
a standard overcurrent device size, the next standard overcurrent device
size shall be used in accordance with 2.40.1.6. The requirement to carry
the locked-rotor currents indefinitely shall not apply to conductors or
devices other than overcurrent devices in the fire pump motor circuit(s).
The requirement to carry the locked rotor currents indefinitely shall not
apply to feeder overcurrent protective devices installed in accordance with
PEC 2017 Rules on Fire Pump
6.95.1.3(C).[20:9.2.3.4]
Exercise #7. What size of Overcurrent Device does a 75-hp, 40V,
3Ø Fire Pump?
(a) 1000A
(b) 800A
(c) 700A
(d) none of these
Referring to Table 430.14.5 (B) (LRC, 3phase, AC), 722 A
• According to Table 2.40.1.6(A) the suitable size is 800 AT
• Equipment Grounding refer to Table 2.50.6.13 is 8.0 mm2
As per Section 4.30.5 is
Locked Rotor Current is 722A
Answer: (b) 800A Overcurrent Device
Protection against a
running overcurrent that
would cause overheating
of the Fire Pump
PEC 2017 Rules on Fire Pump: Introduction
Fire Pump Overload Protection
6.95.1.6 (C) Overload Protection.
Power circuits shall not have automatic protection against
overloads. Except for protection of transformer primaries
provided in 6.95.1.5(C)(2), branch-circuit and feeder conductors
shall be protected against short circuit only. Where a tap is
made to supply a fire pump, the wiring shall be treated as
service conductors in accordance with 2.30.1.6. The applicable
distance and size restrictions in 2.40.2.2 shall not apply.
PEC 2017 Rules on Fire Pump
Article. 6.95 Philosophy
The fire pump motor must run, even if that means
overheating the conductors or damage or destroy
the pump.
“Saving the fire pump but losing the facility isn't
much of a bargain.”
PEC 2017 Rules on Fire Pump: Introduction
What if reliable power
cannot be obtained?
PEC 2017 Rules on Fire Pump: Introduction
(B) Multiple Sources. If reliable power cannot be obtained from
a source described in 6.95.l.3(a), power shall be supplied by
one of the following: [20:9.3.2]
(1) Individual Sources. A combination of two or more of the
sources from 6.95.1.3(A).
(2) Individual Source and On-site Standby Generator. A
combination of one or more of the sources in 6.95.1.3(A) and
an on-site standby generator complying with 6.95.1.3(D).
[20:9.3.4]
Exception to (B)(1) and (B)(2): An alternate source of power
shall not be required where a back-up engine driven or back-up
steam turbine-driven fire pump is installed. [20:9.3.3]IIEE-State of Qatar Chapter
6.95.1.3 Power Source(s) for Electric Motor-Driven Fire Pumps.
Highlights of Article 6.95 Fire Pumps
1. Power Sources for Electric Motor-Driven Fire Pumps
o You can have individual sources or multiple sources.
o You can generate the power onsite.
o If Reliable Source in not available a back-up engine
driven or back-up steam.
2. The service conductors supplying a fire pump
o Must be routed outside a building [6,95.1.6(A)(1)].
o If Routed inside it must have 2 hour fire rating
3. You cannot use phase converters for the fire pump
service [6.95.1.3 (G)].
PEC 2017 Rules on Fire Pump: Introduction
Highlights of Article 6.95 Fire Pumps
4. The goal of not interrupting power to the fire pump is
addressed repeatedly throughout Article 6.95. Then we
discussed in 6.95.4(B)(2) that the overcurrent protective device
(not overload protection, these are two different things).
5. Voltage drop is an issue with fire pumps, because
they place such a huge load on any distribution system.
Article 6.95.1.17 requires that voltage dip no more than
15% of rated controller voltage at the fire pump
controller line terminals (includes cable drop) during
normal starting of the fire pump motor.
PEC 2017 Rules on Fire Pump: Introduction
Highlights of Article 6.95 Fire Pumps
7. Note that what's not mentioned in 6.95.1.3 (or
anywhere else in Article 695) is the use of a softstart.
8. You can use EMT for fire pump control wiring
[6. 95.14(F).
PEC 2017 Rules on Fire Pump: Introduction
Separate Utility Connection.
6.95.1.3 Power Source(s) for Electric Motor-Driven Fire Pumps.
IIEE-State of Qatar Chapter
(2) On-Site Power Production Facility. A fire pump shall be permitted to be
supplied by an on-site power production facility. The source facility shall be
located and protected to minimize the possibility of damage by fire.
[20:9.2.2(3)]
(3) Dedicated Feeder. A dedicated feeder shall be permitted where it is
derived from a service connection as described in 6.95.1.3(a)(1). [20:9.2.2(3)]
6.95.1.3 Power Source(s) for Electric Motor-Driven Fire Pumps.
IIEE-State of Qatar Chapter
TABLES
DW E L L I N G U N I T S
A M PA C I T Y T A B L E
`
By:
Engr. Lauren M. Olivos
PEE, ACPE, AER
By:
DW E L L I N G U N I T S
A M PA C I T Y T A B L E
`
By:
Engr. Lauren M. Olivos
PEE, ACPE, AER