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	Subject - Load Diversity-Non-Dwelling Units rlstoudt I am involved with electrical designs for commercial/light industrial facilities. The experience level of the designers at our firm is limited. We do mostly small commercial & industrial buildings. I am somewhat familiar with NEC with regard to loading requirements. However, the NEC does not cover the diversity factors to be used in sizing motor(HVAC, etc) loads for the type of facilities. We have a debate going in our office as to what diversity factor might be used for the entire building load vs applying diversity factors to each element of the load(lighting, receptacle, motor, resistance heating, etc). Does anyone know of a good reference for load diversity factors for commercial/industrial electrical loads? Scott Vickrey What you are calling diversity factor in the NEC is called demand factor and is defined as the ratio of the maximum demand of a system, or part of a system, to the total connected load of a system or the part of the system under consideration. Demand factor is often shortened to demand. All of these demand factors can be found strewn throughout Article 220. Your not going to get a demand factor for the lighting unless your type of occupancy is listed in Table 220.11. For lighting read section 220.11. Section 22.13 receptacle loads for Nondwelling Units has the applicable demand factors listed in Table 220.13. As for the motors read sections 430.24-26. 430.26 tells you about the demand factors for motors which is basically if you want to apply a demand factor your going to have to conduct an engineering study or evaluation and settle it with your AHJ. Hopefully the future versions of the NEC will fill this void in the code. The heating is covered in section 220.15 which unfortunately suffers the same case by case affliction as the motor feeders. You can be sure your up to code by not using a demand factor for motor and resistive heating feeders. If you absolutely need a demand factor to stay competitive then your going to need the assistance of an EE and/or permission from a willing AHJ. If your having trouble with the code which is the case with almost everyone then use the NEC handbook as opposed to the bare bones codebook. I hope I didn't spend this time telling you what you already know. Remember the AHJ is the key to these gray areas. jackleung For the HVAC or motor load, you should coordinate with the mechanical engineers for the starting or grouping sequences. Just size the electrical load for the worst scenario. e.g. 5 chiller plants are used, but only 3 of them will run at full load. At the same time, only 1 chiller plant will start at a time. Then, you know how to size the power for large chiller load. For others, i.e. lighting, small power etc, local power company may have some data for power per area. For the diversity factor, there is no standard. You should think about the worst senario of the building again. e.g. commercial building. All lightings in office, stair, corridor are expected to be on together for the largest power load consumption. But you can take a smaller diversity factor on back of house or plant room lighting, as they are usually not occupied all the time. Well, there is no absolute answer. Most likely, when the power load is marginal, a debate on diversity factor will start!