Generation connection conditions (GCC). 11 ECBS-10 Electrical Installations of Buildings code, chapter 10, issued by the. This Code Standard for the Electrical Installation of Buildings, EBCS 10: 2013 EBCS-10 is an integral part of the Ethiopian Building Code Standard which SECTION 15: INSTALLATION OF LIGHTING EQUIPMENT EBCS-10: 2013 of the Ethiopian Building Code Standard on Electrical Installation of Buildings. EBCS-10: 2013. EBCS-10 Ethiopian Building Code Standard Electrical Installation of Buildings; EBCS-10 Ethiopian Building Code Standard Electrical Installation of Buildings. Click the start the download. DOWNLOAD PDF. Report this file. Report 'EBCS-10 Ethiopian Building Code Standard Electrical Installation of Buildings'.
There are two terms that seem to confuse designers. These terms are “diversity factor” and “demand factor.” To better understand the application of these terms when calculating the load for a service or a feeder supplying a facility, one must understand their meaning. Diversity factor is the ratio of the sum of the individual maximum demands of the various subdivisions of a system (or part of a system) to the maximum demand of the whole system (or part of the system) under consideration. Diversity is usually more than one. Demand factor is the ratio of the sum of the maximum demand of a system (or part of a system) to the total connected load on the system (or part of the system) under consideration. Demand factor is always less than one.
Application of diversity factor Consider two facilities with the same maximum demand but that occur at different intervals of time. When supplied by the same feeder, the demand on such is less the sum of the two demands. In electrical design, this condition is known as diversity. Diversity factors have been developed for main feeders supplying a number of feeders, and typically, they are 1.10 to 1.50 for lighting loads and 1.50 to 2.00 for power and lighting loads. Diversity factor and load factor are closely related. For example, consider that a feeder supplies five users with the following load conditions: On Monday, user one reaches a maximum demand of 100 amps; on Tuesday, two reaches 95 amps; on Wednesday, three reaches 85 amps; on Thursday, four reaches 75 amps; on Friday, five reaches 65 amps. The feeder’s maximum demand is 250 amps.
The diversity factor can be determined as follows: Diversity factor = Sum of total demands ÷ Maximum demand on feeder = 420 ÷ 250 = 1.68 × 100 = 168% Given Calculate the size of a main feeder from substation switchgear that is supplying five feeders with connected loads of 400, 350, 300, 250 and 200 kilovolt-amperes (kVA) with demand factors of 95, 90, 85, 80 and 75 percent respectively. Use a diversity factor of 1.5. Solution Calculate demand for each feeder:. 400 kVA × 95% = 380 kVA. 350 kVA × 90% = 315 kVA. 300 kVA × 85% = 255 kVA. 250 kVA × 80% = 200 kVA. 200 kVA × 75% = 150 kVA. The sum of the individual demands is equal to 1,300 kVA If the feeder were sized at unity diversity, then 1,300 kVA ÷ 1.00 = 1,300 kVA However, using the diversity factor of 1.5, the kVA = 1,300 kVA ÷ 1.5 = 866 kVA for the feeder. Transformer supplying the main feeder plus wiring methods and equipment can be sized from this kilovolt-ampere rating. Applying demand factors Although feeder conductors should have an ampacity sufficient to carry the load, the ampacity needs not always be equal to the total of all loads on connected branch-circuits. A study of the National Electrical Code (NEC) will show that a demand factor may be applied to the total load.
Remember, the demand factor permits a feeder ampacity to be less than 100 percent of all the branch-circuit loads connected to it. Keep in mind that demand factor is a percentage by which the total connected load on a service or feeder is multiplied to determine the greatest probable load it may be called on to carry.