Under the rule for applying the 75% demand factor to EVSE, which condition is necessary?

Under the rule for applying the 75% demand factor to EVSE, which condition is necessary?

• A. EVSE rated under 500W
• B. Dwelling has at least two fixed in place appliances
• C. Dwelling has at least four fixed in place appliances
• D. Vacant dwelling

Answer: (C)

The key idea is that demand factors let you size loads more realistically by assuming not all equipment runs at full power at once. For EV charging equipment in a dwelling, a 75% demand factor can be used only when the dwelling has enough other fixed loads to establish a baseline of ongoing demand. Specifically, the dwelling must have at least four fixed in-place appliances. When that condition is met, you can treat the EVSE load as 75% of its connected rating for sizing. If there are fewer than four fixed appliances, that 75% factor isn’t applicable, so you’d size the EVSE load without applying that reduction. The other options don’t establish the necessary baseline of four fixed in-place appliances, nor do they relate to when the 75% factor can be used.

The key idea is that demand factors let you size loads more realistically by assuming not all equipment runs at full power at once. For EV charging equipment in a dwelling, a 75% demand factor can be used only when the dwelling has enough other fixed loads to establish a baseline of ongoing demand. Specifically, the dwelling must have at least four fixed in-place appliances. When that condition is met, you can treat the EVSE load as 75% of its connected rating for sizing. If there are fewer than four fixed appliances, that 75% factor isn’t applicable, so you’d size the EVSE load without applying that reduction. The other options don’t establish the necessary baseline of four fixed in-place appliances, nor do they relate to when the 75% factor can be used.