050 National Electrical Code
050 National Electrical Code
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SECTION 050
(b) To size the conductors and the protection, when they are going to be connected
transformers and capacitors, the requirements of Section 150 have
priority over those in Section 050.
Wh Feeder:
Team of Transport the energy from the load side of the
measurement main protective device until the entry of
the protection devices of the derived circuits.
The number and sizing of the conductors of the
feeder, is determined according to a the
General Board characteristics of the system and the demand factors
applicable.
Devices of
protection against Derived Circuits:
overcurrents They transport the energy from the last device
protection up to the outlets for the devices or
electrical equipment.
Figure 050(1)
Identification of the Circuits
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Scope
Support of Rule 050-000. This section specifies the nominal values for the
electric equipment that powers various types of loads. Specifically, it covers the
conductivity capacity of the conductors for the connections, the feeders and
the derived circuits, just like the nominal values of the conductors of
power supply or that feed electrical equipment.
This section not only applies demand factors lower than those of values
nominal data of the characteristic plates (for example, an electric stove of 12 kW
in a housing unit is evaluated at 6 kW), it also allows for other demands
are applied to existing demands (for example, if this same kitchen
electricity is in an apartment block, the demand of 6 kW for a
small apartment in a series of more than 20 housing units is taken at 10%,
So the 12 kW electric stove according to the plate now has a demand of
0.6 kW.
Rule 050-000(b) warns that Section 050 also refers to the amounts
minimum positions on the boards of the derived circuits for units of
housing. In this section, care must be taken to understand the difference between a
single-family housing and a housing unit. Putting it simply:
(a) each single-family home is a housing unit (e.g., duplex, triplex,
bungalow); but
(b) each housing unit is not a single-family dwelling (for example, a
small apartment in a block of apartments.
However, both are residential properties.
Generalities
Sustenance and Purpose of Rule 050-100. Section 160 considers the various
types of loads in watts or volt-amperes, for various types of uses. This
the rule proposes to establish a standard voltage base with which all calculations
from currents, based on the loads expressed in watts or volt-amperes, must be
made. By increasing or decreasing the loads in the utilization system it can
affect the system's tension. Using the standardized tensions without having in
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It accounts for the provided tension, the Code establishes a standard basis for
ensure a safe installation within acceptable voltage ranges.
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Distribution Network
Delivery Point
1% Maximum
(a) Service conductor (See Standard of
BT connections
take-off box and/or
demediation
Energy Meter
(b) Feeder
2.5% Maximum
4% Maximum
Maximum Load or
MaximumDemand
Figure 050-102
Maximum Allowable Voltage Drops in a Circuit
The correct procedure is to calculate the load according to Section 050 and then determine
the dimensions of the conductor and the overcurrent device according to the sections
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corresponding to the Code (for example, Section 030 for Drivers, Section 080
for overcurrent devices).
In paragraph (a), the criterion for continuous loads is that they must be on for a total
for 50% of the time (1 hour) or more in a period of 2 hours, for loads not exceeding
the 225 A.
Similarly, in paragraph (b), the criterion for continuous loads is that they are
lit for a total of 50% of the time (3 hours) or more in any 6-hour period
for loads exceeding 225 A.
A lighting system in a retail store or office would fall under the designation
it continues, just like a commercial water heater, since during normal use
it is on more than 50% of the time, even though it is thermostatically controlled
controlled.
The maximum continuous load supplied by the circuit must not exceed 100% of the
nominal currents of overcurrent devices when used the
nominal currents of Table 2 (conductors in conduits), if:
the capacity of the conductors is equal to or greater than the rated current of the
overcurrent devices;
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The maximum continuous load supplied by the circuit must not exceed 85% of the
nominal current of overcurrent devices when the currents are used
nominal values from Table 1 (outdoor conductors), if any:
the capacity of the conductors is equal to or greater than the nominal current of the
overcurrent devices;
(3) the capacity of the nominal current of the conductors shall be determined from
from Table 1.
Note: In Annex B it indicates that the electrical equipment that is not marked or does not have as
plate data, whose nominal current is continuous, should be considered suitable for operation
continuously at 80% of the nominal current capacity of their devices
overcurrent.
Figure 050-104(4)
Typical Continuous Operation Plate
Examples:
(a) A switch with a 1,000 A fuse is rated for continuous operation at
100% of the rated current capacity of its devices
overcurrent. If the conductors of this switch are going to be laid
In a conduit, what size of continuous load can it supply?
response
This switch with a fuse can power a continuous load of 1,000 A yes
is that:
The conductors have an insulation temperature of the current.
nominal of 70 ºC or 90 ºC; and
the nominal current capacity of the conductors is 1,000 A
determined from Table 2 (in channels).
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Response:
This switch with fuse can supply a continuous load of 1000x85%
= 850 A, yes it is that:
The maximum continuous load supplied by the circuit must not exceed 80% of the
nominal currents of overcurrent devices when using the
nominal currents of Table 2 (conductors in conduit), if:
the capacity of the conductors is equal to or greater than the nominal current of the
overcurrent devices;
The maximum continuous load supplied by the circuit cannot exceed 70% of the
nominal current of overcurrent devices when using the currents
nominal of Table 1 (outdoor conductors), if:
the capacity of the conductors is equal to or greater than the nominal current of the
overcurrent devices;
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Examples:
A switch with a 1,000 A fuse is rated for continuous operation.
to 80% of the nominal current capacity of your devices
overcurrent. If the conductors are going to be laid in a
conduit, What magnitude of continuous load can this feed?
switch?
respuesta
This fuse switch can supply a continuous load of 1,000 x
80% = 800 A, if it is that:
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Response:
Continuous load calculated (500 / 70%) = 714.28 A
Continuous load + 480.00 A
Total combined load 1,194.28 A
Example:
Section 030 applies the reductions of the nominal current capacity between the
80% up to 50%. If 80% of Rule 050-104 is applied and a reduction already exists.
from the capacity of the nominal current of 70% applied to the conductor according to the Rule
030-004(1), 80% of Rule 050-104 should be ignored and only 70% should be applied.
from Section 030.
Note: The reductions of the nominal current capacity of Rule 030-004(8) and (9)
are additional to those of Rule 030-004(1) or (2).
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Service Considerations for Rule 050-104. When they are going to be determined
the maximum permitted currents must take into account the considerations of
Services listed in Annex B under Notes for Rule 050-104(7).
Example:
What section of unipolar AC 90 cable (armored cable - 90 °C) can be used for
a continuous load of 450 A, using continuous operation equipment
nominal at 100%, when the cable is to be buried directly as in Detail 1
from Diagram B4-1?
Steps:
Determine the total of the continuous and non-continuous load.
Continuous load — 450 A
Non-continuous load — Not applicable
(3) Determine the dimensions of the conductors using Table D8B- Detail 1
100%, and the Diagram B4-1
Table D8B - 185 mm2AC 90 °C
(4) Determine the capacity of the conductors, using Rule 050-104(4)(b), the
wiring method, the nominal continuous operating current of the equipment, the
loads of the Step (1), and the nominal insulation temperature of the conductor.
Continuous Load—450 A
Divided by the % of 050-104(4)(b) — 85%
529.4 A
But the load does not continue — Not applicable
Driver Capacity 529.4 A
(6) Select the conductor section from Steps 3 or 5 according to Rule 050-
104(7)
Step 3 or 5 — 185 mm2AC-90 °C
Support and Purpose of Rule 050-106(1). The switches and conductors are
classified into standard dimensions and in some cases it may be advisable
the use of switches and conductors with rated currents lower than the load
calculated.
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With the calculated load, according to this Section, the dimensions must be determined.
minimums of conductors and switches. Rarely, the calculated load is equal to the
standard nominal currents of the switches and conductors. They
establish the conditions under which an electric device of size can be accepted
standard, which may be a little lower than the calculated load. For example, if you
It has a calculated load of 210 A; 5% of 210 = 10.5 A and 210 - 10.5 = 199.5 A.
Support for Rules 050-106 (3), (4) and (5). Lower load demand is
produced
(a) when the loads are controlled to prevent the total load from being
operation at the same time;
(b) when environmental systems such as environmental heating are installed
electricity and air conditioning, which are not used simultaneously; or
(c) when the loads can be in operation at the same time, but are of
cyclical nature and do not produce a demand equal to the total connected load.
Purpose for Rules 050-106 (3), (4) and (5). In Subrule (3), it is indicated that
they must use interlocking controls between the loads, so that two or more
loads cannot operate at the same time. In this case, the load that produces the highest
demand is used to determine the total load.
Subrule (5) is a bit more difficult and subjective. Here we have a number of loads.
they are of a cyclical nature. This means that the loads can be
physically connected and that it is possible to operate them at the same time, but the operation
The system is such that in normal operation they should not operate simultaneously. You are
you can call this, the diversity of the system's operation. A good example can
to be a warehouse with vending machines, or a made-to-order manufacturing plant, where,
Although there are many machines, only a few can be in operation.
simultaneous. Since not all machines can be in operation simultaneously
depending on the business cycle, any decrease in the requirements of the
The burden must be carefully discussed between the parties involved. In such
in cases, it is better to err in having too large a team; otherwise, if it is that
the installed electrical equipment is too small for the load, a modification
very expensive it may be necessary.
Support and Purpose of Rule 050-106 (6). The rules of the sections
individuals are supplemental or amend the General Sections and by
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the following take precedence over such General Sections of the Code, (See the Preface and
Rule 020-002). An example of this would be that, despite the Rule 050-104(5)
it says that the load should not exceed 80% of the nominal current
overcurrent devices, other sections may allow higher values
(example, Section 150 of capacitors).
Support of Rule 050-106 (7). It may be that the application of the factors of
demand on some loads, results in the conductors of a feeder or a
the derived circuit exceeds the requirement of the service conductors.
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of the smallest houses. In the case of the feeders, the minimum section
it should be 2.5 mm2.
The following table outlines the minimum number of spaces for devices against
overcurrent of the branch circuits, for the common capacities of the
feed or supply line in single-family homes. It must be taken into account the
different requirements if a centralized electric stove is used.
Support of Rule 050-108(2). The Code presents a minimum standard and when
There is the possibility of installing additional electrical equipment; space must be planned.
additional resources to be able to feed them.
Support and Purpose of Rule 050-108(3). The limitation of the equipment is recognized.
electricity in apartments and similar buildings and therefore, there is less
minimum space requirements for bipolar overcurrent devices
of 220 V and 35 A. However, when using three-phase equipment or cooking, it must
reserve space for three-phase overcurrent device.
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For homes up to 150 m2, with a load greater than 3 kW and up to 5 kW, and supply
single-phase, space must be provided for five bipolar switches, of which
one must be 20 A.
For homes up to 200 m2with a load between 5 kW and 8 kW, with supply
single-phase, space must be planned for seven switches, of which two must
be of 30 A; or two 15 A tripolar if it were the case of three-phase supply.
This rule is very straightforward. The total habitable area of a single-family home is
determined
(1) Calculating the area of the first floor based on the internal dimensions;
(2) Calculating the area of the upper floors based on the internal dimensions;
y
If the building has a basement, calculating 75% of the basement area
based on the internal dimensions.
Instead of the area being calculated with the internal dimensions, it also
you can use the covered area, since it is a data available in the blueprints
architectural.
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Example:
A two-story single-family home measures 10 m x 12 m with a basement that has
200 mm thick walls. What is the total habitable area of the house?
(1) Area first floor [10 - (2 x 0.200)] x [12 - (2 x 0.200)] 111.36 m2
(2) Area of the upper floors [10 - (2 x 0.200)] - [12 - (2 x 0.200)] = 111.36 2 m
% m2
(3) Basement area [10 (2 x 0.200)] – [12 - (2 x 0.200)] x 7583.52
_______________________
Total 306.24 m2
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Subrule (1)(b) indicates that the minimum nominal current of the conductors should be
A board can be installed with a minimum number of space according to the
Rule 050-108 (4).
For the purposes of Rule 050-104, Subrule (3) of Rule 050-200 proposes
that the charges in Subrules (1) and (2) are not considered continuous; for
there is no need to apply any reduction of the nominal current.
(1) from 050-110 - Calculate the total covered area in m²2Covered area that
is indicated in the Location Plan of
Architecture.
Note: The basic load 050-200(1)(a)(i) and the additional load 050-200(1)(a)(ii)
they consider the loads corresponding to the lighting and outlets of the
housing unit.
It should be noted that the loads for outlets are only for the
that do not exceed 1,500 W or those loads that are characterized by being
installations that have independent branch circuits. For these cases
see the notes from step (7).
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Note: The heating loads, among other similar ones, correspond to:
Heating of surfaces, floors, baseboards.
Pipe heating.
Heating for ice melting.
Sauna (Rule 279-500).
(7) of 050-200(1)(a)(vi) - Calculate for the remaining loads greater than 1,500 W
with a demand factor of 25%, if it has been planned
an electric stove.
If electric cooking has not been planned, it should be considered.
the sum of the loads that exceed 1,500 W up to
a total of 6,000 W at 100%, and the excess of the
6,000 W at 25%.
Note 1: Additional loads over 1,500 W, among others similar
correspond to:
Clothes dryer.
Special outdoor lighting.
Garden lighting.
Facade lighting.
Pool lighting.
Elevators (apply Section 160).
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Example 1:
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Example 2:
Waterheaterforbathroom
The load of the housing unit is 39,300 W, which is equivalent to 103.26 A with supply.
three-phase of 220 V and considering power factor 1.
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Example 3.1:
Three-story housing unit - With Electric Kitchen
A three-story house plus a basement (4 levels), with a covered area of 470 m².
100% of the area of the 1st, 2nd, and 3rd floor 390 m²
75% of the basement area 80 m² 60 m²
Total covered area 450 m²
Steps:
Waterheaterforbathroom
The load of the housing unit is 37,040 W, which is equivalent to 97.32 A, with three-phase supply of
220 V and considering a power factor of 1.
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Example 3.2:
Three-story housing unit - Without Electric Kitchen
A three-story house with a basement (4 levels), which has a covered area of 470 m².
100% of the area of the 1st, 2nd, and 3rd floor 390 m²
75% of the basement area 80 m² 60 m²
Total covered area 450 m²
Steps:
The load of the housing unit is 37,740 W, which is equivalent to 91.28 A, with three-phase supply of
220 V and considering a power factor of 1.
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Example 4.1:
Two-story housing unit - With Electric Kitchen
A two-story house without a basement, which has a covered area of 180 m².
100% of the area of 1erfloor 85 m²
100% of the area of 2ofloor 95 m²
Total covered area 180 m²
Steps:
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Example 4.2:
Two-story housing unit - Without Electric Stove
A two-story house without a basement, which has a covered area of 180 m².
100% of the area of 1erfloor 85 m²
o
100% of the area of 2 floor 95 m²
Total covered area 180 m²
Steps:
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Example 5.1:
Housing unit of an apartment - With Electric Kitchen
A one-story house without a basement, which has a covered area of 90 m².
100% of the area of 1erfloor 90 m²
Steps:
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Example 5.2:
Housing unit of an apartment - Without Electric Kitchen
A one-story house without a basement, which has a covered area of 90 m².
100% of the area of 1erfloor 90 m²
Steps:
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Support of Rule 050-200(2) and (3). When the same service line or feeder
supplies energy to two or more housing units of a condominium, the factors
demand can be applied to the service connection or to the feeder according to the diversity
operational of the housing units.
Purpose of Rule 050-200(2) and (3). In the case of a condominium, it must be applied
the same principles that apply to apartments in buildings, in what
regarding Rules 050-202(3)(a) (i) to (v).
Rule 050-104 and Subrule (3) of Rule 050-200 suggest that the loads of
Subrules (1) and (2) are not considered continuous; therefore, it is not necessary to apply
no reduction of the nominal current capacity.
(1) from 050-200(1) - Calculate the total load for each housing unit
of the condominium in watts;
(4) of 050-202(3)(c) - Calculate the total load of the air conditioning for all
the housing units, using the factor of
demand at 100%
Note: According to Rule 050-106(4), only the one that results in greater of the
application of Steps (3) or (4) can be used.
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Calculate the total load by summing Steps (2), (3), (4), and (5);
Note: The loads are not continuous according to Rule 050-202(2); and it is not necessary to apply
a reduction factor.
Example:
Eight Housing Units in a Condominium - Without Electric Heating
The condominium has 3 kW in lighting for pathways and gardens.
Each housing unit has: 4,000 W for clothes dryer, 4,000 W for air conditioning
air conditioning, 11 kW for electric stove and 2.5 kW for water heater.
Water pump 747 W and lift door 373 W.
Covered area of each house 330 m²
100% of the area of 1hefloor 120 m²
100% of the area of 2ofloor 130 m²
2
75% of the basement (of 80 m) ) 60
Total covered area 310 m²
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Steps:
050-200(1) The load of each housing unit is 19,620 W
Support of Rule 050-202(1), (2) and (3). Despite the fact that the individual units
housing can be treated as single-family homes, the operational diversity
from a group of housing units feeding from a single feeder or
connection allows for the application of demand factors.
Purpose of Subrule 050-202(1), (2) and (3). The applicable factors are indicated.
allowed demands when calculating the minimum capacity of the conductors of the
incoming or feeder, which supplies housing units in a building of
departments. The basic principles for a single-family home are applied
according to Subrule (1)(a), with the sole exception of the step added when calculating the load
basic for recognizing a small one-bedroom apartment.
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Subrule (3) specifies the applicable demand factors allowed for the
calculate the minimum capacity of the service or feeder conductors,
from the main connection in an apartment and similar buildings. In order to
use this Subrule to calculate the minimum capacity of the conductors
The feeder or supply must have a minimum of two loads of units.
housing connected to the service or feeder conductors. When it
use this Subrule to calculate the minimum capacity of a feeder that has a
minimum load of two housing units from the main connection, others
rules can be applied (for example, 160-110 for motor loads). It must be
use Subrule (4) when the service connection or the feeder conductors
they only supply the loads outside of the housing units (for example, loads of
passages and external light, loading laundry rooms, elevator loads.
The steps to follow to calculate the minimum capacity of the conductors of the
the connection or the main feeder of an apartment building are the
next:
Note: The basic load (i) and the additional loads (ii) and (iii) consider the loads
corresponding to the lighting and outlets of the apartment.
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Note: The loads of water heaters, among other similar ones, correspond to:
Water heater for bathroom.
Electric shower.
Hot tub heater.
Pool heater.
(h) of 050-202(1)(b) - Use the highest of the calculated loads in 050-202 (1)
(a) or (b) 25 A.
Note: The loads are not continuous according to Rule 050-202(2); and it is not necessary to apply.
a reduction factor.
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(6) Determine, from the loads in Step (5), which loads are continuous and which are not.
do not continue according to 050-104(3);
(7) Apply the current capacity reduction factor according to Rule 050-
104(4) or (5) depending on the nominal current of the equipment used and of the
Tables used to determine the capacity of conductors:
Calculate the total load by adding the loads calculated from Steps (2), (3), (4) and
(7).
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Example 1.1:
Calculation of loads for a typical 45 m apartment2With Electric Cooking
Typical apartment with 45 m² of covered area.
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Example 1.2:
Calculation of loads for a typical 45 m apartment2With Electric Kitchen
Typical apartment with 45 m² of covered area.
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Example 2.1:
Load calculation for a typical 90 m Department2With Electric Kitchen
Typical apartment with 90 m² of covered area.
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Example 2.2:
Calculation of loads for a Typical Department of 90 m2Without Electric Stove
Typical apartment with 90 m² of covered area.
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Example 3.1:
Calculation of loads for a building with 8 typical apartments of 180 m2With Electric Kitchen
Typical apartment with 180 m² of covered area.
The building has a basement of 650 m² for parking and has the following loads:
Exterior lighting 10 points of 100 W each.
02 Elevators of 5,500 W each.
2 water electric pumps of 1190 W each (with alternating operation).
2 drainage electric pumps of 750 W each (with alternating operation).
CO extractor of 1,500 W.
2 lift doors of 375 W each.
Central intercom, 1 point of 500 W.
Alarm Central, 1 point of 800 W.
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they must support a current of 298.5 A, with a three-phase power supply of 220 V and considering a
power factor 1.
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Example 3.2:
Calculation of loads for a building with 8 typical apartments of 180 m2Without Electric Stove
Typical apartment with 180 m² of covered area.
The building has a basement of 650 m² for parking and has the following loads:
Exterior lighting 10 points of 100 W each.
2 elevators of 5,500 W each.
02 water pumps of 1,190 W each (with alternating operation).
02 drainage electric pumps of 750 W each (with alternating operation).
1,500 W CO extractor.
02 sliding doors of 375 W each.
Central intercom, 1 point of 500 W.
Alarm control center, 1 point of 800 W.
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they must withstand a current of 274.8 A, with a three-phase power supply of 220 V and considering a
power factor 1.
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Example 3.3:
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Example 4.1:
Using the previous steps:
DEPARTMENTS
Type A
4
80
12
3
4
4
Steps:
(1) Calculation of the load for each type of apartment:
Type A
Not applicable (N/A) --
(b) (1)(a)(i) First 45 m2of area 1,500
Next 45 m2 of area 1,000
(d) (1)(a)(iii) - Next 95 m2 or fraction --
e) (1)(a)(iv) - Electric heating space loads
according to Rule 207-116(2) (a) and (b)
First 10 kW at 100% 4,000
balance at 75% --
(f) Load of kitchens, first 12 kW 6,000
balance at 40% (C: 40%*2 kW)
(g) Other loads over 1,500 W at 25% of the demand factor
Clothes dryers 4 kW x 25% 1,000
Water heaters 3 kW x 25% 750
Total in W: 14,250
(h) Sizing of feeders
220 V current, three-phase 37.4
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Note - All external loads on the departments are assumed to be continuous loads.
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The requirements of Rule 050-104(4) and (5) must be applied to the loads.
outside of the housing units, which are continuous according to Rule 050-202(2).
Example 4.2:
Using the loads from Example 4.1 of Rule 050-202(1), (2), and (3), the calculation is made.
minimum capacity of the feeder conductors required to supply the
loads outside the housing units.
The minimum nominal current of the equipment is 126 558/(380 x 1.73) = 192 A.
The minimum nominal current of the equipment is 101 246/(380 x 1.73) = 154 A.
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The Subrule (1) indicates the method for determining the minimum capacity of the
conductors of the service or feeder for a school. Subrule (2) indicates
the demand factors that need to be applied to the minimum capacity of the connection
or of the drivers calculated in Subrule (1).
The steps to follow to calculate the minimum capacity of the conductors of the
feed or the main feeder of a school or college are the
next:
(1) from 050-204(1) - determine the total area of the school in m2, based on
the external dimensions;
(2) from 050-204(1) - determine the total area of the school's classrooms in m2;
(3) of 050-204(1)(a) - calculate the basic load in watts for the area of classrooms,
multiplying the total area of halls in m2for 50 W/m2;
(4) of 050-204(1)(b) - calculate the load of the remaining area of the school,
multiplying the remaining area in m2by 10 W/m2.
(6) calculate the total load of the building, summing the steps (3),
(4) and (5);
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(b) calculate the remaining load of the building taking into account the
75% of the remaining total load of the building, minus
any load of electric ambient heating (see
step (7);
(10) determine the wiring method that will be used, and how much of the load it is
continue according to 050-104(3), and from there apply the requirements of 050-104(4) or
(5);
dimension the conductors of the feeder or the service connection and the devices
about overcurrent.
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Example 1:
Determine the minimum capacity of the service conductor for a school with a total area
built of 900 m2of which 750 m2it is the total area of classrooms. The other loads in the school
They total 65,000 W, with an electric ambient heating load of 90,000 W. The voltage
The supply of the connection is 380/220 V, three-phase with 4 wires.
Steps:
Pot. Dem.
Inst. Max.
(W) (W)
050-
204(1)(c)
Other school burdens 65,000
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Example 2:
Steps:
050-
204(1)(c)
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Subrule (1) provides the method for determining the minimum capacity of the conductors.
of the feeders or the supply for a hospital. Subrule (2)
give the demand factors that should be applied to the minimum capacities of the
incoming or feeder calculated in Subrule (1).
(1) from 050-206(1) - determine the total area of the hospital in m2, based on
in the external dimensions;
(2) from 050-206(1) - determine the total area of high intensity areas,
like the operating room, of the hospital in m2;
(6) calculate the total load of the building by adding the steps
(3), (4) and (5);
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(10) determine the wiring method that will be used, and how much of the load is
continue according to 050-104(3), and from there apply the requirements of 050-104(4) or
(5);
(11) size the connection or the feeder conductor and the devices of
overcurrent.
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Example 1:
Determine the minimum capacity of the service conductor for a hospital with
total built area of 12,000 m2, of which 300 m2high-intensity areas. The
The supply is 380/220 V, three-phase, 4 wires.
The hospital has the following loads:
Electric ambient heating 1,200,000 W
Air conditioning 100,000 W
Equipment and other charges 165,000 W
Steps:
The total area of the hospital is 12,000 m.2;
The total area of the high-intensity areas is 300 m2;
(3) The basic load of the hospital 20 x = 240,000
12,000 m2 W;
The load of the high intensity areas 100 x 300
= 30,000 W;
The total of the other charges in the hospital
Electric ambient heating 1,200,000 W
Air conditioning is not considered (see 050-106(4)) ------
Equipment and other loads 165,000 W
Total 1,365,000 W;
The total load of the building
Step (3) 240,000 W
Step (4) 30,000 W
Step (5) 1,365,000 W
Total 1,635,000 W;
The total load of the building minus any ambient heating load
electric
1,635,000 - 1,200,000 = 435,000 W;
Since the total area of the hospital is more than 900m2use step (9) to calculate
the demand factors;
(9) (a) The total load of the electric ambient heating with the factors of
demand of Section 270.
1,200,000 x 75% = 900,000 W;
calculate the load per square meter
435,000 / 12,000 = 36.2 W/m2;
2
(b)(i) calculate the load for the first 900 m of the area
80% x 36.2 x 900 = 26 064 W;
(b)(ii) calculate the load for the remaining area of the hospital
65% x 36.2 x (12,000 - 900) = 261 183 W;
(c) calculate the minimum capacity of the supply connection
1,806 A
(10) Determine the wiring method that will be used, the amount of load
continues; and the demand factors according to Rule 050-104(4) or (5).
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Example 2:
Determine the minimum capacity of the conductor for the service connection for a hospital with
total built area of 900 m2, of which 150 m2high intensity areas. The
Other hospital loads have a total of 65,000W, with ambient heating of 90.
The supply connection voltage is 220/380, three-phase with four wires.
Steps:
The total area of the hospital is 900 m2;
The total area of high-intensity areas is 150 m2;
(3) The basic load of the hospital 20 x 900m2 =18,000 W;
(4) The load of the high intensity areas 100 x 15,000
150 W;
The total area of the other loads in the hospital
155000 155,000 W;
The total load of the building
Step (3) 18,000 W
Step (4) 15,000 W
Step (5) 155,000 W
Total 188,000 W;
The total load of the building minus any ambient heating load
electric 98,000
= 98 000 W;
Since the total area of the hospital is more than 900m2, use step (9) to calculate.
the demand factors;
(9) (a) The total load of the electric ambient heating with the factors of
demand of Section 270.
67,500 = 67 500 W;
(b) the load of the rest of the building is
80% of 98,000 78,400 W;
(c) calculate the minimum capacity of the supply connection
(67 500 + 78 4000) / (380 x 1,73) = 222 A;
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(1) from 050-208(1) - determine the total area of the hotel, motel, dormitory, or
similar establishments in m2based on the
external dimensions;
(2) of 050-208(1)(a) - calculate the basic load in watts by multiplying the area
total of the building in m2per 20 W/m2;
(3) of 050-208(1)(b) - calculate in watts the total lighting load for the
special areas, such as ballrooms,
based on the rated power of the electrical equipment
installed;
(4) of 050-208(1)(c) - calculate the total load in watts, including the heating
electric environmental, the air conditioning and the loads of
force, based on the rated power of the equipment
installed electric
Note: When calculating the load for motors installed in the feeder, it should be
comply with Rule 160-110(1).
Calculate the total load of the building by adding the steps (2), (3) and (4);
Note: The following demand factors can be applied:
(6) subtract any electric ambient heating load from the total load of the
building calculated in step (5);
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(b) calculate the nominal load per square meter, dividing the remainder of the
total load of the building minus the loads of environmental heating
electrical (see Step 7) by the total area of the building (see Step 1);
(i) calculate the load for the first 900 m2of the total area of the
building in watts, taking 80% of the load per square meter
multiplied by 900;
65% of the load per square meter multiplied by the total area
from the building in excess of 900 m2;
(c) calculate the minimum capacity of the conductor of the service connection or of the
feeder, summing steps 8(a), (8)(b)(i), and (8)(b)(ii);
(9) determine the wiring method that will be used, and how much of the load is
continue according to 050-104(3), and then apply the requirements of 050-104(4)
o (5);
Example 1:
Determine the minimum capacity of the service conductors for a hotel with
total built area of 4,800 m2 The supply is 380/220 V, three-phase, 4-wire.
The total load of the building minus any ambient heating load.
electric
958 000 – 500 000 = 458,000 W;
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Since the total area of the hotel is more than 900m2use step (8) to calculate the
demand factors;
(a) The total load of electric ambient heating with the factors of
demand of Section 270.
125000 375,000 W;
(b) calculate the load per square meter
458 000 / 4 800 95.4 W/m2
2
(b)(i) calculate the load for the first 900 m of area
80% x 95,4 x 900 = 68 688 W;
(b)(ii) calculate the load for the remaining area of the hotel
65% x 95,4 x (4 800 – 900) = 241 839 W;
(c) calculate the minimum capacity of the supply connection
(375,000 + 68,688 + 241,839) / (380 x 1.73) = 1,043 A
The following table details the steps to follow to apply step (9). The only step
what has not been considered was how much of the load was continuous and how much was not continuous.
In the example, the calculated load is considered as continuous. This consideration is
it must take into account consulting all parties involved with the electrical installation.
Support and Purpose of Rule 050-210. This rule provides a basis on which
the minimum capacities of the establishments can be determined, apart from the
covered by Rules 050-200 to 050-208. A method is established by which
can properly determine the capacity of the service conductors or
of the feeder that supplies various types of establishments. The concept,
previously presented, in watts per square meter and the application of various
percentages of demands according to the establishment have been extended through the use
from Table 14.
The loads such as electric ambient heating, air conditioning, power and
lighting, they are treated separately from their nominal powers, with factors of
demands permitted by other Sections of the Code, (for example, ambient heating
electric and motor load.
The steps to follow are:
(1) from 050-210 - determine the total area of the establishments in m2
based on the external dimensions;
(2) from 050-210(a) - calculate the basic load in watts, for the type of
establishment using watts per square meter
from Table 14, for the particular type of
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(4) of 050-210(b)- calculate the total special load in watts, such as the
electric ambient heating, air conditioning, the
power loads, lighting of showcases and
stage lighting, based on power
nominal of the installed electrical equipment with any
demand factor allowed by the Code;
Note: When calculating the load for motors installed on the feeder, it should be
comply with Rule 160-110(7).
(6) determine the wiring method used; how much of the load is continuous according to
050-104 (3); and then apply the requirements of 050-104(4) or (5);
(7) determine the dimensions of the service or feeder conductor and of the
overcurrent devices.
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Example 1:
Calculate the minimum conductor capacity for the following establishments.
a shopping center. The voltage is 380/220, three-phase with 4 wires.
Office:
Area 200 m2
Loads 10 kVA air conditioning
electric ambient heating 25,000 W
computer load 27.3 A at 220 V
water heater 1 500 W
Steps:
Area 200 m2;
2
(2) Table 14 - 50 W/m
basic load 50 x 200 = 10,000 W;
(3) Table 14 - 90%, basic load 10,000 x 90% 9,000 W;
(4) Special loads:
air conditioning, is not considered (see Rule 050-106(4)) --------
electric ambient heating 25,000 x 0.75 18,750 W
computer load 27.3 x 220 = 6,000 W
water heater 1,500 W
Total 26 250 W
Minimum capacity of the service connection conductor
(9,000 + 26,250) / (380 x 1.73) = 53.6 A
Mini-market:
- Area - 300 m2
Loads refrigerators 36.4 A at 380 V
showcase lighting 4 000 W
electric ambient heating 30,000 W
30 kVA air conditioning
water heater 4,000 W
Steps:
(1) Area 300 m2;
Table 14 30 W/m2basic load 30 x 300 9,000 W;
Table 14 100%, basic load 9,000 W;
Special loads:
refrigerators 36.5 x 380 x 1.73 24,000 W;
showcase lighting = 4,000 W;
air conditioning 30,000 VA
water heater 4,000 W
Total 62,000 W
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Hobby Store:
Area 100 m2
- Loads:
window display lighting 2,000 W
electric ambient heating 12,000 W
water heater 1 500 W
Steps:
(1) Area- 100 m2;
2
(2) Table 14 - 30 W/m
, basic load 30 x 100 = 3,000 W;
(3) Table 14 - 100%, basic load = 3,000 W;
Special loads:
showcase lighting = 2,000 W;
electric ambient heating 12,000 x 75% = 9 000 W;
water heater 1,500 W;
Total 12,500 W;
Minimum capacity of the connection conductor
(3,000 + 12,500) / (380 x 1.73) = 23.6 A
Bank:
Area - 120 m2
Cargas special lighting 1 500 W
electric ambient heating 15,000 W
3000 W water heater
Steps:
(1) Area- 120 m2;
(2) Table 14 50 W/m2basic load 50 x 120 = 6,000 W;
(3) Table 14 100%, basic load = 6,000 W;
(4) Special loads:
special lighting 1,500 W;
electric ambient heating 15,000 x 75% 11,250 W;
water heater = 3 000 W;
Total 15,750 W;
Pharmacy:
Area 150 m2
Cargas
special lighting 3 000 W
electric ambient heating 15,000 W
water heater 3000 W
10 kVA air conditioning
11 A refrigerators at 380 V
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Steps:
(1) Area- 150 m2;
(2) Table 14 30 W/m2Basic load 30 x 150 = 4,500 W;
(3) Table 14 100%, basic load = 4,500 W;
(4) Special loads:
special lighting = 3,000 W;
electric environmental heating 15,000 x 75% 11,250 W;
water heater = 3 000 W;
air conditioning - is not considered (see Rule 050-106(4)) ----- ---
refrigerators = 7 200 W
Total = 24 450 W;
Beauty Salon
150 m2
loads
special lighting 4,000 W
electric ambient heating 10,000 W
water heater 6,000 W
air conditioning 12 kVA
hair dryers 12,000 W
Steps:
2
(1) area - 150 m
;
(2) Table 14 30 W/m2basic load 30 x 150 = 4,500 W;
(3) Table 14 90%, basic load 4 050 W;
(4) special loads:
special lighting = 4 000 W;
ambient heating - not considered (see Rule 050-106(4)) -------
water heater 6000 W;
air conditioning = 12,000 W
hair dryers 12,000 W
Total 34,000 W
Support for Rule 050-212. The area method for calculating the load is not
always practical, especially when the lighting loads are not confined
to a single geographical location within the building. In this case, another method
Apart from the watts per square meter, it should be used.
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Consider ten circuits of 15 A at 220 V loaded with 4.4 A each and feeding
lighting loads throughout the building (the exits of the signs and of the
lighting can be on the same circuit.
Derived Circuits
Support of Rule 050-300. Kitchen loads vary in different
establishments and certain criteria are required to establish the appropriate capacity
in the branch circuits that supply the kitchen electrical equipment.
Purpose of Rule 050-300. Subrule (1) establishes the principles for calculation.
the capacities of the derived circuits, for electric stoves in units of
housing, which are similar to those previously found in Rules 050-
200 and 050-202 for incoming and feeder demands, except that in this
The claim is only for the drivers of derived circuits.
In Rule 050-200, the demand for a 12 kW electric kitchen was 6 kW. Here.
it is a little bigger, reaching 8 kW. The calculations for the rated currents.
that exceed 12 kW is the same: 40% of the amount of the rated current over
12 kW.
Example:
A single-family housing unit has a 14 kW electric kitchen, 220 V.
The same electric stove in another application that is not a housing unit
unfamiliar, it will have a contribution from the supply based on the demand of
establishment. The capacity of the derived circuit must be the nominal current
from the electric kitchen and in our example, it is 14 kW.
For any other case that is not a housing unit, it must be used by
less one conductor for 14 kW, which would be:
A 16 mm conductor2At 90 ºC, for a single-phase branch circuit
A 6 mm conductor2At 90 ºC, for a three-phase derived circuit.
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Subrule (2) refers to kitchen units, separate from fixed installation, for example,
a stove or an oven. It should be taken into account that the requirements for the
derived circuits for these units are also covered in Rule 150-744. The
Rule 150-746 covers the supply connections for electric kitchens.
Rule 050-300(1).
Subrule (4) recognizes that stoves and similar appliances, which are not fixed installations, that
they connect with cords built into the device, they must not exceed 1,500 W and
They can be operated from a standard kitchen countertop outlet.
The length of the window is measured along the base and 650 W per meter is applied.
to file a lawsuit. The fractions that may remain are not considered, they
you can take advantage of this and say that the figure applies to each full meter. A
A 6-meter window will have a demand of 650 x 6 = 3,900 W.
In Subrule (2), some loads with cyclical or intermittent nature are also
You continue. A water heater is a good example of this. When the tank is
cold, the unit can operate for more than two hours until the
desired water temperature. Depending on the use of water, the unit may be
It is in a frequent cycle. This load can be considered continuous.