When using the optional calculation for a dwelling service, loads above the initial 10 kVA are assessed at what percentage?

The correct answer indicates that when assessing loads for a dwelling service that exceed the initial 10 kVA, these additional loads are calculated at 40%. This calculation is based on standard practices laid out in electrical code provisions, which aim to account for the typical usage and safety factors associated with increased electrical demand.

The rationale behind applying a reduced percentage to loads exceeding 10 kVA is to allow for more accurate estimation of the capacity needed without overestimating the load. In residential settings, the majority of the demand typically falls within the initial kVA range, which is why a lower percentage is used for loads above that threshold. This practice helps to balance the potential for future expansion of electrical systems while still ensuring reliability and safety in residential service.

In analyzing the other options, it is important to understand that the percentages provided do not align with industry standards for this specific scenario. A higher percentage would unnecessarily inflate the load calculation, potentially leading to undersized one or elevated infrastructure costs, detracting from both efficiency and practicality. Thus, the 40% assessment is considered suitable for loads above the specified threshold.