Settle a Bet on 220.12(A)

[winterovereverything]

Happy Friday Folks,

Before wrapping up work in the office today, a coworker and I shared a difference in opinion about the correct application of Table 220.12 in the 2020 NEC. As far as I am aware, 220.12 is used to calculate branch circuits with lighting loads so long as the actual fixtures themselves do not exceed the value of that which is calculated through the table. A coworker of mine shared a different perspective, that 220.12 supersedes the values of lighting fixtures installed in a branch circuit. The way that I have always performed my calculations is to consider both and that whichever load is higher (either 220.12 or lighting fixture load) is what would determine the branch circuit size. Am I wrong? By all accounts 220.10 and 220.12(A) seem to reiterate my point but I'm curious to hear your thoughts about this.

-WOVA

 

[tjdilly]

Table 220.12 in my opinion is out of date for most states for anything other than a conservative service sizing & branch circuit quantity. With the adoption of IECC 2015+ in the vast majority of states the wattage per square foot limitations are much lower than 220.12 when it comes to actual specified light fixture wattages. I always use the actual lighting loads for branch circuiting, and 220.12 in my service calculations.

I don't even think it's possible to exceed the values in 220.12 unless you are ignoring IECC/Ashrae 90.1/Title 24.

 

[steve66]

The handbook has a note following 220.14(D) that seems to imply you are correct for everywhere except a dwelling. That is, the lighting load must be based on the installed fixtures if that load exceeds table 220.12. However, it also seems to say 220.12 is the only calculation needed for a dwelling unit lighting load, and no additional calc. is needed for actual installed lights.