•  Current Carrying Capacity and Correction Factors 
•  Base Conditions 
•  Voltage Drop 
•  Energy Conscious Solution 
•  Example of Economic / Ecologic Calculation 
The CableApp uses the correction factors as defined in the Table B.52.1 of IEC 60364552. This allows the user to tailor a circuit rating for their given prescribed installation. These correction factors cover the following parameters: ambient temperature (air, and ground where appropriate), soil resistivity, depth, proximity of multiple circuits for ladder, tray, direct in ground and in ducts in the ground.
Rating Factor Type  Correction Table Ref. IEC 60364552 HD 60364552 
Applicable Reference Method & Ratings Table(s) 
Rating factors for ambient air temperatures other than 30°C, for cables in the air  Table B.52.14  Ref Method: C, E, F, G, K, L, R, S Tables: B52.2, B.52.4, B.52.3, B.52.5, B.52.10, B.52.11, B.52.12, B.52.13 
Rating factors for ambient ground temperatures other than 20°C, for cables direct buried or in buried ducts  Table B.52.15  Ref Method: D1, D2, H, I, J, M, N, P, Q Tables: B.52.2, B.52.3, B.52.4, B.52.5 
Rating factors, for cables direct buried in the ground or in buried ducts, for soil resistivities other than 2.5 K.m/W  Table B.52.16  Ref Method: D1, D2, H, I, J, M, N, P, Q Tables: B.52.2, B.52.3, B.52.4, B.52.5 
Rating factors for depths of laying other than 0.7m for direct buried cables and cables in buried ducts  Ref Method: D1, D2, H, I, J, M, N, P, Q  
Rating factors for one circuit or one multicore cable or for a group of circuits of multicore cables  Table B.52.17  Ref Method: A1, A2, B1, B2, C Tables: B.52.2, B.52.3, B.52.4, B.52.5 
Rating factors for more than one circuit, singlecore or multicores cables laid directly in the ground  Table B.52.18  Ref Method: D2 Tables: B.52.2, B.52.3, B.52.4, B.52.5 Tables: 14 (HD 6033G), 14 (HD 6035G) 
Rating factors for more than one circuit, cables laid in ducts in the ground  Table B.52.19  Ref Method: D1 Tables B.52.2, B.52.3, B.52.4, B.52.5 
Rating factors for groups of more than one multicore cables in free air  Table B.52.20  Ref Method: E Tables: B.52.10, B.52.11, B.52.12, B.52.13 Tables: 15 (HD 6033G), 15 (HD 6035G) 
Rating factors for groups of one or more circuits of singlecore cables in free air  Table B.52.21  Ref Method F Tables: B.52.10, B.52.11, B.52.12, B.52.13 
Rating Factor Type  Correction Table Ref IEC 605022 
Applicable Reference Method & Ratings Table(s) 
Rating factors, for depths of laying other than 0.8m, for cables direct buried in the ground  Table B.12  Ref Method H, I, M, P Tables: B.2, B.3, B.6, B.7 
Rating Factors, for depths of laying other than 0.8m, for cables in buried ducts  Table B.13  Ref Method J, N, Q Tables: B.2, B.3, B.6, B.7 
Rating factors, for monoconductor cables direct buried in the ground, for soil resistivities other than 1.5 K.m/W  Table B.14  Ref Method H, I Tables: B.2, B.3, B.6, B.7 
Rating factors, for monoconductor cables in buried ducts, for soil resistivities other than 1.5 K.m/W  Table B.15  Ref Method J Tables: B.2, B.3, B.6, B.7 
Rating factors, for multiconductors cables buried direct in the ground, for soil resistivities other than 1.5 K.m/W  Table B.16  Ref Method M, P Tables: B.2, B.3, B.6, B.7 
Rating factors, for multiconductors cables in buried ducts, for soil resistivities other than 1.5 K.m/W  Table B.17  Ref Method N, Q Tables: B.2, B.3, B.6, B.7 
Rating factors, for more than one circuit of multiconductors cables direct buried in the ground  Table B.18  Ref Method: M, P Tables: B.2, B.3, B.6, B.7 
Rating factors, for more than one circuit of monoconductor cables direct buried in the ground  Table B.19  Ref Method: H, I Tables: B.2, B.3, B.6, B.7 
Rating factors, for more than one circuit of multiconductors cables in buried ducts in the ground  Table B.20  Ref Method: N, Q Tables B.2, B.3, B.6, B.7 
Rating factors, for more than one circuit of monoconductor cables in buried ducts in the ground  Table B.21  Ref Method: J Tables: B.2, B.3, B.6, B.7 
Rating factors for groups of more than one multicore cable in free air  Table B.22  Ref Method: O, R Tables: B.2, B.3, B.6, B.7 
Rating factors for groups of more than one mono conductor cables in free air  Table B.23  Ref Method: K, L Tables: B.2, B.3, B.6, B.7 
Rating Factor Type  Correction Table Ref HD 620 S2  Applicable Reference Method & Ratings Table(s) 
Rating factors, for monoconductor cables, direct buried in the ground  Ref Method: H, I Table 7 

Rating factors, for monoconductor cables, in air  Ref Method: K, L Table 8 

Rating factors, for multiconductors cables, direct buried in the ground  Ref Method: M, P Table 9 

Rating factors, for multiconductors cables, in air  Ref Method: O, R Table 10 

Rating factors, for monoconductor cables direct buried in ground, for soil resistivities other than 1.0 K.m/W  Table 6 of Part 10B  Ref Method H, I Tables: B.2, B.3, B.6, B.7 
The published current ratings in IEC / HD 60364552 are based on the following conditions:
Parameter  Condition 
Ambient Air temperature  30°C 
Ambient Ground temperature  20°C 
Base installation depth (cables installed in the ground)  0.8m 
Base soil resistivity (cables laid in the ground)  2.5 K.m/W 
The published current ratings in IEC 605022 are based on the following conditions:
Parameter  Condition 
Ambient Air temperature  30°C 
Ambient Ground temperature  20°C 
Base installation depth (cables installed in the ground)  0.8m 
Base soil resistivity (cables laid in the ground)  1.5 K.m/W 
The published current ratings in HD 620 S2 are based on the following conditions:
Parameter  Condition 
Ambient Air temperature  30°C 
Ambient Ground temperature  20°C 
Base installation depth (cables installed in the ground)  0.7m 
Base soil resistivity (cables laid in the ground)  1.0 K.m/W 
The CableApp executes voltage drop calculations using the formulae for voltage drop published in Appendix G of IEC 60364552, for the appropriate cable and installation type. The voltage drop between the origin of an installation and any load point shall not be greater than the values below:
Cable Type  Lighting %  Other uses % 
A  LV installations supplied directly from a public low voltage distribution system  3  5 
B  LV installation supplied from private LV supply  6  8 
C  MV installations 
As far as possible, it is recommended that voltage drop within the final circuits do not exceed those indicated in installation type A
When voltage drops exceed the values shown above, larger cables (wires) must be used to correct the condition
When the main wiring systems of the installations are longer than 100 m, these voltage drops may be increased by 0,005% per meter of wiring system beyond 100 m, without this supplement being greater than 0,5%
Voltage drop is determined from the demand by the currentusing equipment, applying diversity factors where applicable, or from the values of the design current of the circuits
A greater voltage drop may be accepted:
 for motor during starting periods
 for other equipment with high inrush current,
provided that in both cases it is ensured that the voltage variations remain within the limits specified in the relevant equipment standard
The following temporary conditions are excluded:
 voltage transients
 voltage variation due to abnormal operation
Voltage drop may be determined using the following formulae:
u  voltage drop [V] 
b  coefficient equal to 1 for threephase circuits, and equal to 2 for singlephase circuits 
ρ1  resistivity of conductors in normal operation [Ω.mm2/m] 
L  length of the line [m] 
S  crosssection area of conductors [mm2] 
cos Φ  power factor (usual, cos cos Φ = 0.8, sin Φ = 0.6) 
λ  reactance per unit length of conductors (0.08 mΩ/m in the absence of other details) 
I  design current [A] 
Uo  voltage between line and neutral [V] 
The following information provides guidance in energy efficiency, and the calculation method used to provide the Energy Conscious Solution in the CableApp
The calculation requires the end user to define some of the parameters used in the calculation, within the "Settings" menu of the CableApp
The potential savings should be considered as guidance only
According to Joules Law, whenever a conductor carries current, it will generate heat (thermal energy)
Thermal energy of a cable corresponds to the following general formulae:
Where:
E_{p}  energy generated (lost on the line) [kWh] 
n  number of loaded conductors (2 for singlephase/dc or 3 for threephase) 
c  number of cables per phase 
R  conductor resistance [Ω / km] 
L  cable length [km] 
I  line current [A] 
t  time [h] 
If the crosssectional area (S) of a cable is increased, there will be a corresponding reduction in the resistance (R). When carrying the same current I, there will be a reduction in the energy loss (E_{P}). This energy saving can be quantified both as a cost saving in electricity bills and a reduction in CO_{2} emissions.
The cable itself will be more expensive because it will have a higher crosssectional area (S) but the installer will benefit from the following:
 Lower running costs, reduced energy bills.
 Reduced CO_{2} emissions, therefore an environmentally better proposition.
 Extended design life for the cable because it is operating at a lower temperature.
Standard design life is based on the cable being at its maximum load (maximum operating temperature) for every hour of that defined life in years.
 Improved short circuit capability  larger crosssectional areas will carry higher currents in a fault condition.
 Potential to uprate the cable to carry higher loads in the future.
As a rule, cables do not carry the same current (I) continuously. For this reason, it is advisable to consider the mean square value of the current over time or at least to make an estimate.
The CableApp will offer by default the average usage of load (I ') equal to 75% of I, but other values can be selected or defined by the user in the "Settings" of the CableApp:
100% I
40% I (residential)
60% I (public place)
75% I (industrial)
Other %
Thus, the energy saved (E_{A}) by installing conductors of lower resistance (R_{2}) than (R_{1}) will be:
Having calculated the saved energy, the economic savings can be calculated (A£) and the savings in CO_{2} emissions since we have defined the electricity tariffs (Energy Price) in RON/kWh (in the "settings") and the approximate values of CO_{2} emissions (A_{CO2}) kg per kWh generated taking account of the country’s energy mix is defined by the CableApp (note, this value cannot be modified by the user).
Entering the value of the electricity rate and the value of CO_{2} emissions per kWh will therefore give the savings achieved by installing crosssection conductors with a larger section.
Energy Price  0,45 RON / kWh  (is defined by the user in "Settings") 
CO_{2} Emissions  0.40 kg CO_{2} / kWh  (RO default value, not possible to edit) 
Let’s assume we want to carry out an economic and ecological calculation as follows:
System  threephase; 130 m; 268A (dummy data)
CableApp Proposed Technical Size  95mm² copper conductor
To calculate the savings, we must consider increasing the crosssectional area from 95mm² to the next largest standard crosssection, which is 120mm².
Conductor material  Voltage class  Cross section  Resistance 
Aluminum  Low Voltage  2,50  14,538 
Aluminum  Low Voltage  4,00  8,903 
Aluminum  Low Voltage  6,00  5,539 
Aluminum  Low Voltage  10,00  3,700 
Aluminum  Low Voltage  16,00  2,295 
Aluminum  Low Voltage  25,00  1,442 
Aluminum  Low Voltage  35,00  1,043 
Aluminum  Low Voltage  50,00  0,770 
Aluminum  Low Voltage  70,00  0,533 
Aluminum  Low Voltage  95,00  0,385 
Aluminum  Low Voltage  120,00  0,305 
Aluminum  Low Voltage  150,00  0,249 
Aluminum  Low Voltage  185,00  0,198 
Aluminum  Low Voltage  240,00  0,152 
Aluminum  Low Voltage  300,00  0,122 
Aluminum  Low Voltage  400,00  0,096 
Aluminum  Low Voltage  500,00  0,076 
Aluminum  Low Voltage  630,00  0,061 
Aluminum  Low Voltage  800,00  0,050 
Aluminum  Low Voltage  1000,00  0,042 
Copper  Low Voltage  1,00  21,657 
Copper  Low Voltage  1,50  14,478 
Copper  Low Voltage  2,50  8,866 
Copper  Low Voltage  4,00  5,516 
Copper  Low Voltage  6,00  3,685 
Copper  Low Voltage  10,00  2,190 
Copper  Low Voltage  16,00  1,376 
Copper  Low Voltage  25,00  0,870 
Copper  Low Voltage  35,00  0,627 
Copper  Low Voltage  50,00  0,464 
Copper  Low Voltage  70,00  0,322 
Copper  Low Voltage  95,00  0,232 
Copper  Low Voltage  120,00  0,185 
Copper  Low Voltage  150,00  0,151 
Copper  Low Voltage  185,00  0,121 
Copper  Low Voltage  240,00  0,094 
Copper  Low Voltage  300,00  0,076 
Copper  Low Voltage  400,00  0,062 
Copper  Low Voltage  500,00  0,051 
Copper  Low Voltage  630,00  0,042 
Conductor material  Voltage class  Cross section  Resistance 
Aluminum  Medium Voltage  50,00  0,822 
Aluminum  Medium Voltage  70,00  0,568 
Aluminum  Medium Voltage  95,00  0,411 
Aluminum  Medium Voltage  120,00  0,325 
Aluminum  Medium Voltage  150,00  0,265 
Aluminum  Medium Voltage  185,00  0,211 
Aluminum  Medium Voltage  240,00  0,161 
Aluminum  Medium Voltage  300,00  0,129 
Aluminum  Medium Voltage  400,00  0,101 
Aluminum  Medium Voltage  500,00  0,080 
Aluminum  Medium Voltage  630,00  0,063 
Aluminum  Medium Voltage  800,00  0,051 
Aluminum  Medium Voltage  1000,00  0,042 
Copper  Medium Voltage  50,00  0,494 
Copper  Medium Voltage  70,00  0,342 
Copper  Medium Voltage  95,00  0,247 
Copper  Medium Voltage  120,00  0,196 
Copper  Medium Voltage  150,00  0,159 
Copper  Medium Voltage  185,00  0,128 
Copper  Medium Voltage  240,00  0,098 
Copper  Medium Voltage  300,00  0,079 
Copper  Medium Voltage  400,00  0,063 
Copper  Medium Voltage  500,00  0,051 
Copper  Medium Voltage  630,00  0,042 
Reference is made in the background of the App to the electrical resistance table (above), calculated at a given average operating temperature. The R value for the next size is selected, in this case 120mm².
For the simplicity of the calculation, both conductors are assumed to operate at the same temperature. The resistance for the larger conductor will be lower than given in the table when carrying the same load, because the larger conductor will operate at a lower temperature. The subsequent savings will be a conservative estimate.
If the calculation is undertaken for an annual usage, then the time (t) will be 365days • 24h = 8760 h.
We will assume the average usage is 75% (default value in the App, but this can be changed in the “settings” menu)
Now we can calculate the energy that can be saved in a year using 120 mm² instead of 95 mm².
E_{A}  = (n/c • (R_{150}  R_{185}) • L • (%U • I')² • t) / 1,000 
= (3/1 • (0.231  0.185) • 0.13 • (0.75 • 268)² • 8760) / 1000  
= 6480 kWh 
We have defined the chosen installation with a tariff rate for electrical energy of 0.45 RON / kWh (remember the user should define their Tariff in the "settings").
The CableApp uses a default value for CO_{2} emission equal to 0.40 kg CO_{2} / kWh.
Energy Price  0.45 RON / kWh  (value can be changed in "settings" menu) 
CO_{2} emissions  0.40 kg CO_{2} / kWh  (value proposed by default) 
A_{RON}  = 6480 kWh • 0.45 RON / kWh = 2916 RON  
A_{CO2}  = 6480 kWh • 0.40 kg CO_{2} / kWh = 2592 kg CO_{2} 