pvgreeze
Member
- Location
- Philadelphia
- Occupation
- Electrical Engineer
Hi all, question that I'm sure has been discussed ad nauseam in various forms. With the 2023 NEC more explicitly defining a line side PV disconnect as a "service disconnect," this topic seems relevant.
Here is the scenario: For a roof mounted PV system with a line side PV DS interconnection, we need to establish a grounding electrode system separate from the existing service. NEC 250 has several definitions, requirements, tables, etc. outlining the Grounding Electrode System (GES), the Grounding Electrode Conductor (GEC) and the differences between that and the Equipment Grounding Conductor (EGC).
250.53 outlines the installation requirements for the GES. A basic GES is a ground rod, with installation requirements clearly outlined in 250.53(A). 250.53(A)(2) requires a "supplemental eletrode," with examples given as an additional ground rod, bonding to a grounding electrode conductor, bonding to a grounded service-entrance conductor (the service neutral), etc.
250.58 requires that a common grounding electrode exist "where separate services, feeders, or branch circuits supply a building" and that "Two or more grounding electrodes that are bonded together shall be considered a single [GES] in this sense."
So, with a new service DS, which needs a connection to the existing GES per 250.58, can that existing GES service as the "supplemental electrode" to another ground rod as required by NEC 250.53(A)(2)? Basically, do I need two ground rods and a connection to the existing GES or can I get away with one ground rod and a connection to the existing GES. All connections to the GES are sized per 250.66 and are considered grounding electrode conductors (GECs).
Would love to know people's thoughts. Thanks!
Here is the scenario: For a roof mounted PV system with a line side PV DS interconnection, we need to establish a grounding electrode system separate from the existing service. NEC 250 has several definitions, requirements, tables, etc. outlining the Grounding Electrode System (GES), the Grounding Electrode Conductor (GEC) and the differences between that and the Equipment Grounding Conductor (EGC).
250.53 outlines the installation requirements for the GES. A basic GES is a ground rod, with installation requirements clearly outlined in 250.53(A). 250.53(A)(2) requires a "supplemental eletrode," with examples given as an additional ground rod, bonding to a grounding electrode conductor, bonding to a grounded service-entrance conductor (the service neutral), etc.
250.58 requires that a common grounding electrode exist "where separate services, feeders, or branch circuits supply a building" and that "Two or more grounding electrodes that are bonded together shall be considered a single [GES] in this sense."
So, with a new service DS, which needs a connection to the existing GES per 250.58, can that existing GES service as the "supplemental electrode" to another ground rod as required by NEC 250.53(A)(2)? Basically, do I need two ground rods and a connection to the existing GES or can I get away with one ground rod and a connection to the existing GES. All connections to the GES are sized per 250.66 and are considered grounding electrode conductors (GECs).
Would love to know people's thoughts. Thanks!