Single family home with mother-in-law apartment, 200 amp service, all electric except for gas heat. Customer wants to install a 50 amp hot tub. Using 220.83(A) to determine if service is of sufficient capacity since no HVAC is being added. Should the existing HVAC load and new hot tub load be added to 220.83(A)(1)through(A)(4)before taking first 8kVA of load at 100% and the remainder at 40%.

My read is to do the calcs on the EXISTING items, then add the hot tub.

One may also consider installing an amp recorder to 'see' the real world numbers to have actual (real) load.

John

PS: Welcome to ECN