This is an existing house which the original plans dont match what is in the field. Right now they have the whole house on the gen. The permit drawing, they had taken one of the panels out of the gen. so the calculations were okay, now we have a case wher we need to kow the highedt KW demand, here in South Florida usually is the cooling the highest during the peak summer
Are you talking about the optional calc?
What I don't understand is how the plans approval office can require a letter from the electrical utility for an OPTIONAL standby generator. If the transfer is automatic they can only require that the ampacity of the generator is capable of carrying the loads that will remain connected to it after the load is transferred. Birken Vogt and others have pointed out the calculated load should be the only thing at issue. There is no requirement in the US National Electric Code (NEC) for an optional standby generator to meet a particular load level as long as it is appropriately protected against overload. Given the diversity of dwelling loads, on which the service sizing of 83% of load is based, if the calculation is properly done it is super unlikely that the generator will fail to carry the calculated load. 65,000 watts at 240 volts will provide 270 amperes.
