Interpretation #8072

Original Request

Code Version: 2017
Code: NEC
Code Description
Chapter
Section: 705.12
Topic: Conductor sizing in accordance with NEC 705.12(A)

Question

When connecting a photovoltaic power system on the supply side of the service disconnecting means, does 705.12(A) require an increase in the size of the service conductors if the overcurrent device(es) fed by the photovoltaic system does not exceed the rating of the service conductors?

Attachments

Supply Side Connecitons.pdf Download

Answer Published 02/27/2018 at 11:12 AM

No. The supply side service conductors are not required to be increased in size. The load for the structure did not increase. The size of the conductor between the inverter output and the service equipment needs to be the larger of 2014 NEC 690.8 (A) or 690.8 (B). NEC 705.12 (A) which states that, “The sum of the ratings of all overcurrent devices connected to power production sources shall not exceed the rating of the service.” The size of the wire connected to the supply side of the service disconnect is determined by 690.8 and the capacity of that supply is limited by 705.12. The size of the service conductors do not require adjustment.

Commentary

None.