In dwelling load calculations, what is the purpose of applying demand factors?

In dwelling load calculations, what is the purpose of applying demand factors?

• A. To increase the calculated load for safety
• B. To reduce the calculated load by considering diversity
• C. To ignore variability in load
• D. To replace overcurrent protection planning

Answer: (B)

Demand factors in dwelling load calculations account for diversity of usage; not all electrical devices are used at the same time, so the total expected load is less than the sum of all connected ratings. By applying a demand factor to groups of loads, you get a realistic design load for service equipment and feeders, which helps prevent over-sizing while still meeting actual needs. For example, although many appliances could have high individual ratings, they rarely peak simultaneously, so applying these factors yields a practical, safe sizing. This approach does not increase the calculated load, it acknowledges variability in usage, and it’s not about replacing overcurrent protection planning—for sizing the service and conductors you use demand factors to reflect typical simultaneous use.

Demand factors in dwelling load calculations account for diversity of usage; not all electrical devices are used at the same time, so the total expected load is less than the sum of all connected ratings. By applying a demand factor to groups of loads, you get a realistic design load for service equipment and feeders, which helps prevent over-sizing while still meeting actual needs. For example, although many appliances could have high individual ratings, they rarely peak simultaneously, so applying these factors yields a practical, safe sizing. This approach does not increase the calculated load, it acknowledges variability in usage, and it’s not about replacing overcurrent protection planning—for sizing the service and conductors you use demand factors to reflect typical simultaneous use.