Mike Dolt Enterprises
Mike Dolt Enterprises
User: winterovereverything, Location: California
Asked on: Friday, August 8, 2025 at 4:09 pm EDT
Answered on: Friday, August 8, 2025 at 4:09 pm EDT
Question: 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
Happy Friday to you too, WOVA!You're on the right track. Let's break down the situation and clarify the application of 220.12.
Here's the core understanding
220.12 provides minimum general lighting load requirements. This is crucial. It's a minimum based on the occupancy and square footage. It's there to ensure a building has adequate general lighting, regardless of the actual fixtures installed. Actual fixture loads must always be considered. You cannot ignore the actual wattage of the lighting fixtures.
Your Approach is Correct
Your method of comparing the 220.12 calculated load and the actual lighting fixture load and using the higher of the two is the correct and conservative (and therefore safer and code-compliant) approach.
Why your coworker is incorrect
Your coworker is misinterpreting the intent of 220.12. 220.12 doesn't supersede the actual fixture load. It provides a floor for the load calculation. The actual load is always considered, and if the actual load exceeds the 220.12 value, the actual load governs.
Let's clarify with the NEC
220.10 General
"Branch-circuit, feeder, and service calculations shall be in accordance with this article or as permitted elsewhere in this Code." This establishes the general rule - use this article unless the Code specifically says otherwise. It doesn't say to ignore actual loads.
220.12 General Lighting
"The unit loads specified in Table 220.12 shall be considered as the minimum acceptable load to provide for a reasonable level of illumination, unless other information is available." This is Key. The loads are
minimums. 220.12(A) General Lighting
"The unit loads specified in Table 220.12 shall be the minimum acceptable loads for dwelling units and all other occupancies. The calculated general lighting load shall not be less than the sum of the unit loads specified in Table 220.
12." Reinforces the minimum aspect.
Example
You calculate the general lighting load for an office space using Table 220.12 and get 3,500 VA. You then add up the actual wattage of all the LED fixtures installed in that space, and it totals 4,000 VA. You must use 4,000 VA for your branch circuit, feeder, and service calculations, not 3,500 VA.
In summary:
Think of 220.12 as a safety net. If the actual lighting load is lower than the 220.12 calculated load, you use the 220.12 value to ensure adequate lighting is provided. If the actual lighting load is higher, you must use the actual load to avoid overloading the circuit.Hopefully this provides some additional clarity and context to discuss with your coworker. Have a great weekend! Flag for review