"All Others" Lighting Load Demand Factor

Hi, all.

I have always seen the general lighting load demand factor (not dwelling units, hospitals, hotels, or warehouses) set at 125% on projects on different companies. However, NEC table 220.42 states that "all others" lighting loads are to be demanded at 100%. There's an asterisk note there, but it refers only to hospital and hotel loads, not the "all others".

I have asked this to coworkers and they have said this 125% is in response to articles 210.20(A) and/or 215.2(A)(1)(a). Problem is (to me, anyway) is that those articles are specific to branch OCPD and feeders, not demand factors.

Does anyone have a better explanation to the use of this 125% for demand factor for general lighting loads? Or perhaps the use of 125% is not really required by NEC?

Thanks in advance,


  • The demand factor for common lighting loads seems to be misunderstood in some way. The demand factor for "all other" loads, which are general lighting loads rather than specialised hospital or hotel loads, is 100% according to NEC table 220.42; any special remarks provided are not immediately relevant.

    Each firm may apply its own internal rules or preferences when determining these values; the NEC may not mandate that businesses utilise 125% as their demand factor when it comes to general lighting loads. It's important to keep in mind that the NEC rules specify that a demand factor of 100% is permissible for "all other" loads.

  • Thank you,  . Just as I thought - the NEC does not require this 125% factor demand, but only 100% as a minimum (for the "all others" class) - so, engineers are welcomed to increase that factor if they so choose.


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