BS 7450:1991

Committees responsible
National foreword
Method
Introduction
1. Scope
2. Normative references
3. Symbols
4. Calculation of total costs
5. Determination of economic conductor sizes
Annexes
A. Examples of calculation of economic conductor sizes
B. Mean conductor temperature and resistance
Tables
A.1 Cable details
A.2 Economic loading
A.3 Current-carrying capacity criterion
A.4 Economic loading, standard conductor size for all
     sections
Figures
A.1 System layout
A.2 Economic current ranges
A.3 Variation of cost with conductor size

For economic choice of conductor size based on joule losses. Voltage dependent losses are not considered.

This International Standard deals solely with the economic choice of conductor size based on joule losses. Voltage dependent losses have not been considered.

NOTE 1 It is recommended that the method given in this standard should not be used for cables operating on system voltages equal to or greater than the following (see IEC 287):

NOTE 2 Modifications to the method given in this standard in order to take dielectric losses into account are under consideration.

Likewise, matters such as maintenance, energy losses in forced cooling systems and time of day energy costs have not been included in this standard.

An example of the application of the method to a hypothetical supply system is given in Annex A.