MAIN CIRCUIT BREAKER DOWNSIZING (MBD) & LOAD CALCULATIONS
“Why would I need load calculations,” you ask?
Landing a PV breaker tie-in in the main electrical panel requires you to adhere to the NECs 120% rule. Sometimes, the existing electrical panel’s bus and main circuit breaker rating leaves you outside of the 120% rule, and with a PV OCPD requirement too large to land on the bus bar. One option, in order to comply with the NEC rule, is to perform a main circuit breaker downsize. A MBD allows you to tie-in a larger PV OCPD then what the existing main circuit breaker would have allowed.
But first! The existing loads in the service panel must be calculated to determine If the main breaker can be downsized and to what rating. When uploading your projects with main breaker downsizes, just upload a panel schedule with a full list of existing breaker sizes and its associated load (i.e. 30A HVAC, 20A washer, 15A gen lighting, etc.) and/or clear photos of the loads in the main service panel and we’ll take care of the load calculations for you.