Part 8 chap 1-appendices a, b, c
- 1. 81 Appendix A Maximum Demand and Diversity Some information on the determination of the maximum demand for an electrical installation are provided in this appendix. It also includes some notes on the application of allowances for diversity. It is impossible however, to specify the appropriate allowances for diversity for every type of installation since determination of such allowances calls for special knowledge and experience. The figures shown in Table A1 are therefore, intended to act as guideline. The current demand of a final circuit is determined by summing the current demands of all points of utilization and equipment in the circuit. Typical values to be used for this summation are given in Table A2. For blocks of residential dwellings, large hotels, and industrial and large commercial premises, allowances are to be assigned by a competent engineer. The current demand of a circuit supplying a number of final circuits may be assessed by applying the allowances for diversity given in Table A1 to the total current demand of all the equipment supplied by that circuit. In the table, the allowances are appraised either as percentages of the current demand or, where followed by the letters f.l., as percentages of the rated full load current of the current using equipment. After the design currents for all the circuits have been determined, enabling the conductor sizes to be chosen, it is necessary to check that the limitation on voltage drop is met. Table A 1 Allowances for Diversity Purpose of final circuit Type of Premises fed from conductors or switchgear to which diversity applies Individual household installations, including dwellings of a block Small shops, stores, offices and business premises Small hotels, boarding houses, guest houses, etc. 1. Lighting 66% of total current demand 90% of total current demand 75% of total current demand 2. Cooking appliances 10 amperes + 30% f.l. of connected cooking appli‐ ances in excess of 10 amperes + 5 amperes if socket outlet is incor‐porated in unit. 100% f.l. of largest appliance + 80% f.l. of 2nd largest appliance + 60% f.l. of remaining appliances 100% f.l. of largest appliance + 80% f.l. of 2nd largest appliance + 60% f.l. of remaining appliances 3. Motors (other than lift motors which are subject to special consideration) ______ 100% f.l. of largest motor + 80% f.l. of 2nd largest motor + 60% f.l. of remaining motors 100% f.l. of largest motor + 50% f.l. of remaining motors. 4. Water heater (ther‐ mostatically contro‐ lled) No diversity allowable
- 2. 82 Table A 2 Current Demand to be Assumed for Points of Utilization and Current using Equipment Point of Utilization or Current‐using Equipment Current Demand to be Assumed 15A socket outlets 13A socket outlets 5A socket outlets Protected outlets other than the above mentioned socket outlets Lighting outlet House hold cooking appliance All other stationary equipment / Appliances 15A with diversity applied 13A with diversity applied At least 0.5A Rated current Current equivalent to the connected load, with a minimum of 100W per lamp holder The first 10A of the rated current plus 30% of the remainder of the rated current plus 5A if a socket outlet is incorporated in the control unit Standard rated current or nominal current.
- 3. 83 Appendix B Useful Tables Relating to Conductor Sizes Table B 1 Number of Single‐core Wire of Different Sizes for Various Sizes of Metal Conduits Conductor Cross‐ sectional Area (mm2) Conduit Diameter (mm) 19 25.4 31.8 38 51 63.5 Number of wires that can be drawn 1.5 5 10 14 ‐ ‐ ‐ 2.5 5 8 12 ‐ ‐ ‐ 4.0 3 6 10 ‐ ‐ ‐ 6.0 2 5 8 ‐ ‐ ‐ 10.0 ‐ 3 5 6 ‐ ‐ 16.0 ‐ ‐ 3 6 ‐ ‐ 25.0 ‐ ‐ 2 4 6 7 35.0 ‐ ‐ ‐ 3 5 6 50.0 ‐ ‐ ‐ ‐ 4 5 Table B 2 Number of Single‐core Wires of Different Sizes for Various Sizes of PVC Conduits Conductor Cross‐sectional Area (mm2) Conduit Diameter (mm) 19 25 32 38 51 Number of wires that can be drawn 1.5 6 10 14 ‐ ‐ 2.5 5 10 14 ‐ ‐ 4.0 3 6 10 14 ‐ 6.0 2 5 8 11 ‐ 10.0 ‐ 4 7 9 ‐ 16.0 ‐ 2 4 5 12 25.0 ‐ ‐ 2 2 6 35.0 ‐ ‐ 2 2 5 50.0 ‐ ‐ ‐ 2 3 Table B 3 Wire Gauges Gauge System Diameter Cross‐sectional Weight of Weight of Area Copper Aluminium AWG SWG (mm) (mm2) (kg/km) (kg/km) 6/0 ‐ 14.73 170.46 1515.4 460.4 5/0 ‐ 13.11 134.92 1199.4 365.0 ‐ 7/0 12.70 126.68 1126.2 342.1 ‐ 6/0 11.79 109.09 969.8 294.6 4/0 ‐ 11.68 107.22 953.2 289.4 ‐ 5/0 10.97 94.56 840.7 255.4 3/0 ‐ 10.41 85.16 757.2 229.6 ‐ 4/0 10.16 81.70 720.7 219.6 ‐ 3/0 9.449 70.12 623.4 189.4 2/0 ‐ 9.271 67.51 600.1 182.1 ‐ 2/0 8.839 61.36 545.5 165.7 0 ‐ 8.255 53.52 475.8 144.4 ‐ 0 8.230 53.19 472.9 143.6 ‐ 1 7.620 45.60 405.4 123.1
- 4. 84 Gauge System Diameter Cross‐sectional Weight of Weight of Area Copper Aluminium AWG SWG (mm) (mm2) (kg/km) (kg/km) 1 ‐ 7.341 42.22 376.2 114.5 ‐ 2 7.010 38.60 343.1 104.2 2 ‐ 6.553 33.94 299.8 90.80 ‐ 3 6.401 32.18 286.1 86.89 ‐ 4 5.893 27.27 242.5 73.63 3 ‐ 5.817 26.57 236.2 72.01 4 ‐ 5.182 21.09 187.5 57.11 ‐ 6 4.877 18.68 166.1 50.44 5 ‐ 4.623 16.78 149.2 45.25 ‐ 7 4.470 15.70 139.5 42.39 6 ‐ 4.115 13.30 118.2 35.91 ‐ 8 4.065 12.97 115.3 35.02 7 9 3.658 10.507 93.41 28.49 8 10 3.251 8.302 73.80 22.59 ‐ 11 2.948 6.818 60.61 18.41 9 ‐ 2.896 6.585 58.54 17.91 ‐ 12 2.642 5.480 48.72 14.80 10 ‐ 2.591 5.272 46.87 14.21 ‐ 13 2.337 4.284 38.08 11.58 11 ‐ 2.311 4.196 37.30 11.26 12 ‐ 2.057 3.325 29.55 8.934 ‐ 14 2.032 3.243 28.83 8.756 13 15 1.828 2.627 23.35 7.093 14 16 1.626 2.075 18.45 5.621 15 ‐ 1.448 1.646 14.64 4.460 ‐ 17 1.422 1.589 14.13 4.290 16 ‐ 1.295 1.318 11.72 3.532 ‐ 18 1.291 1.168 10.38 3.154 17 ‐ 1.143 1.026 9.122 2.808 18 19 1.016 0.8107 7.207 2.223 19 20 0.9144 0.6567 5.838 1.773 20 21 0.8128 0.5189 4.613 1.401 21 ‐ 0.7239 0.4156 3.695 1.111 ‐ 22 0.7112 0.3973 3.532 1.073 22 ‐ 0.6428 0.3243 2.883 0.8756 ‐ 23 0.6096 0.2919 2.595 0.7881 23 ‐ 0.5733 0.2588 2.301 0.6990 ‐ 24 0.5588 0.2453 2.181 0.6620 24 ‐ 0.5105 0.2047 1.820 0.5527 ‐ 25 0.5086 0.2021 1.797 0.5473
- 5. 85 Appendix C Completion Certificate Form (Electrical Works) I / we certify that the installation detailed below has been installed by me / us and tested and that to the best of my / our knowledge and belief, it complies with the requirements of Bangladesh National Building Code and the Electricity Act of Bangladesh (as modified up to 1987) Electrical Installation at . _____________________________________________ Voltage and system of supply _________________________________________ Particulars of Works : a) Internal Electrical Installation No. Total load Type or system of wiring i) Light points ii) Fan points iii) Socket points 2-pin 5 A 3-pin 13 A Flat pin 3-pin 15 A Round Pin b) Others Description hp/kW Type of starting 1) Motors i) ii) iii) 2) Other plants c) If the work involves installations of over head line and/or underground cable 1) i) Type and description of over head line ii) Total length and number of spans iii) Number of street lights and its description 2) i) Total length and size of underground cable ii) Number of joints
- 6. 86 End joint Tee joint Straight through joint d) Earthing i) Description of earthing electrode ii) Number of earth electrodes iii) Type and short description of Brass Earthing Clamp iv) Number of Brass Bolt Nuts provided in the Brass Earthing Clamp for the termination of Earth Lead Cables v) Size of each of the main earth lead cables vi) Number of main earth lead cables Test Results : a) Insulation Resistance values: i) Insulation resistance of the whole system of conductors to earth _________________ mega ohms ii) Insulation resistance between the phase conductor and neutral Between phase R and neutral _________________ mega ohms Between phase Y and neutral _________________ mega ohms Between phase B and neutral _________________ mega ohms Conductor characteristics Conductor flexibility Tinned copper 0.5 mm diameter Conductor material annealed copper