Okay, let's break down how to calculate the demand load for those ranges using Table 220.55, Column C, in the 2023 National Electrical Code (NEC).Here's the step-by-step process and the reasoning:1. Understand the Table 220.55, Column C

This column is used specifically for ranges with a nameplate rating not over 12 kW and for over 12 kW up to 27 kW. You said each range is 13kw so we use this.2.

Calculate the Initial Demand Load

Since we have (10) 13kw ranges this falls under row 9 and will be 25kW plus 5% for each range after the 5th range. This means we will add 5% x 5 ranges.3.

Add the Percentage Adjustment

5% per range 5 ranges = 25%4.

Apply the Adjustment

25kW 25% = 6.25kW 25kW + 6.25kW = 31.25kW

Therefore, you would add 25% to the 25kW demand to arrive at a total demand of 31.25kW. Important Considerations



Local Amendments

Always check with your local electrical inspector or authority having jurisdiction (AHJ) to see if there are any local amendments to the NEC in your area that might affect this calculation.

Feeder and Service Size

This demand load is used to calculate the required ampacity of the feeder conductors and the service supplying these ranges. You'll need to perform additional calculations (including voltage drop) to properly size the conductors, overcurrent protection, and other components.

Other Loads

This calculation only considers the ranges. You must include all other loads in the vocational school when determining the overall service size. This includes lighting, HVAC, receptacle outlets, and any other electrical equipment.

Safety First

Always consult with a qualified electrical engineer or licensed electrician for the final design and installation of the electrical system. This is a complex task that requires expertise to ensure safety and code compliance.

Labeling

Make sure all ranges are clearly labeled with their nameplate ratings (voltage, wattage/kVA, amperage).

Disclaimer: I am an AI Chatbot. This information is for general guidance only and should not be considered a substitute for professional advice from a qualified electrical engineer or licensed electrician. Always refer to the latest edition of the NEC and consult with your local AHJ for specific requirements in your area. Flag for review