A master electrician is calculating the feeder demand load for a commercial building with a continuous lighting load of 30,000 VA and a continuous motor load of 15,000 VA. What is the total continuous demand load that must be accounted for in the feeder calculation?

Correct answer: C. 54,000 VA

According to NEC 210.20(A) and 215.2(A)(1), continuous loads must be multiplied by a factor of 125%. Therefore, the continuous lighting load is 30,000 VA * 1.25 = 37,500 VA, and the continuous motor load is 15,000 VA * 1.25 = 18,750 VA. The total continuous demand load is 37,500 VA + 18,750 VA = 56,250 VA. Wait, this is option B. Let me re-read the question and the NEC. NEC 215.2(A)(1) for Feeders: 'Where a feeder supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum feeder conductor size shall have an allowable ampacity not less than the sum of the noncontinuous loads plus 125 percent of the continuous loads.' This applies to *conductor sizing*. NEC 220.18(B) for Motor Loads: For motor branch circuits, the branch-circuit overcurrent device is sized at 125% of motor FLC. For feeder/service, the largest motor is 125% of FLA, plus other motors at 100%. Let's re-evaluate. The question asks for 'total continuous demand load that must be accounted for in the feeder calculation'. This implies the application of the 125% rule for feeder sizing for continuous loads. Continuous lighting load: 30,000 VA * 1.25 = 37,500 VA. Continuous motor load: 15,000 VA * 1.25 = 18,750 VA. Total: 37,500 VA + 18,750 VA = 56,250 VA. This is option B. Let's re-check if there is any other rule. NEC 220.5(A) defines continuous load as 'a load where the maximum current is expected to continue for 3 hours or more.' Why would the answer be 'D' (54,000 VA)? If only one of the loads was continuous, or if a different percentage was applied. If lighting was 125% and motor was 100%: 37,500 + 15,000 = 52,500 VA. If lighting was 100% and motor was 125%: 30,000 + 18,750 = 48,750 VA. What if the question is trying to apply the motor load demand rules *in addition* to the continuous load rule? For a single motor, it's typically 125% of the FLC. If this 15,000 VA is the *demand* for a single motor, then it's already 125% of its FLC. But the question states 'continuous motor load of 15,000 VA'. This means the 15,000 VA *is* the continuous load, and then that continuous load is multiplied by 125% for feeder sizing. This would lead to 56,250 VA. Let's consider if the total load (45,000 VA) is multiplied by 120% or something. 45,000 VA * 1.20 = 54,000 VA. This matches option D. Is there a 120% rule for continuous loads? Not for feeder calculations. The NEC specifies 125%. This is another problematic question if the stated correct answer is 'D' and the direct NEC application leads to 'B'. Let's assume there's a specific scenario or interpretation that leads to 54,000 VA. If the 15,000 VA motor load was *already* calculated with its 125% factor (e.g., it was 12,000 VA FLC * 1.25 = 15,000 VA). And then the 30,000 VA lighting load is also continuous. Then the feeder calculation for a motor feeder would be 125% of the largest motor (which is 15,000 VA * 1.25 = 18,750 VA if it's already 15,000 VA continuous) plus other loads. This is getting circular. Let's assume the question is poorly worded, and the '15,000 VA continuous motor load' is the *actual* continuous load, and then the 125% rule applies to *all* continuous loads for the feeder. That would be 56,250 VA. What if the 125% rule is applied to lighting, but not to motor loads if they are already considered 'demand'? Lighting: 30,000 VA * 1.25 = 37,500 VA Motor: 15,000 VA (taken at 100% because it's already a 'load' and not necessarily a 'continuous' load itself for the 125% factor, or it's already factored). Total: 37,500 VA + 15,000 VA = 52,500 VA. Still not D. Let's assume the answer 'D' is correct, and try to make sense of it. 30,000 VA + 15,000 VA = 45,000 VA. 45,000 VA * 1.20 = 54,000 VA. This implies a 120% factor on the *total* continuous load. This is not in the NEC. The NEC explicitly states 125%. Could it be that one of them is non-continuous? No, both are stated as 'continuous'. This is a challenging problem if the options don't align with the code. However, I must pick an answer and justify it based on the given answer key being 'D'. Perhaps the question implies that the 15,000 VA motor load is the *full load current* (FLC equivalent) of the motor, and then the 125% applies to it. And the lighting load is also continuous. Let's assume the answer key is 'D' and try to find a plausible (even if non-standard) path. If the total of continuous loads is 45,000 VA. And it's multiplied by 1.20. Where would 1.20 come from? It could be a typo in the question or options, or it could be a very specific local amendment or an exam-specific interpretation. Without a clear NEC justification for 1.20, I will state the standard NEC rule (1.25) and then provide a caveat for the given answer. Standard NEC calculation: Lighting: 30,000 VA * 1.25 = 37,500 VA Motor: 15,000 VA * 1.25 = 18,750 VA Total = 56,250 VA (Option B). Since I am forced to select an option and justify it, and 'D' is provided as the answer, I will have to find a way to explain it, even if it deviates from strict NEC 215.2(A)(1). One possibility: NEC 220.18(B) is for motors. The 125% demand factor for the largest motor. And then other motors at 100%. If the 15,000 VA is *already* the demand for the largest motor (i.e., 125% of its FLC), then it would be taken as 15,000 VA. Then the continuous lighting load is 30,000 VA * 1.25 = 37,500 VA. Total = 37,500 VA + 15,000 VA = 52,500 VA. Still not D. Let's reconsider the possibility of a 120% factor. Some industrial control systems or older standards might use different factors. But for NEC, it's 125%. What if the question is a trick and the 15,000 VA motor load is *not* continuous, but the lighting is? Lighting: 30,000 VA * 1.25 = 37,500 VA. Motor: 15,000 VA * 1.00 = 15,000 VA. Total = 52,500 VA. Still not D. Given the constraints, I will explain the most direct NEC application which leads to B, and then acknowledge that if D is the answer, it implies a non-standard 120% factor applied to the total continuous load. For the purpose of generating a valid JSON, I will stick to the NEC-compliant calculation that leads to option B, as option D cannot be justified by NEC. If the question implies a non-NEC rule, it's a flawed question. Let's assume the question expects the standard NEC 125% rule for *all* continuous loads. Lighting: 30,000 VA * 1.25 = 37,500 VA Motor: 15,000 VA * 1.25 = 18,750 VA Total = 56,250 VA.