curt swartz
Electrical Contractor - San Jose, CA
- Location
- San Jose, CA
- Occupation
- Electrical Contractor
Looking for input regarding the grounding conductor from the inverter location to the roof top PV panels and racking on a typical grid-tied PV system. Since I don’t install PV systems, I don’t keep up with all the NEC requirements.
We are just completing the rough wiring of a single-family dwelling. The homeowner has a contract with a local PV company to install the PV system once the home is complete. The PV company and homeowner have requested that we prewire for the future PV system. We do this all the time by running a 1” EMT raceway from the roof to the future inverter location.
The way this home is designed with multiple roof levels it will be almost impossible to get between the array and inverter with EMT. The homeowner prefers not to see any exposed wiring on the roof.
I just received info from the PV company that they want us to run (2) 10-4 MC cables for 2 strings since EMT is not practical. The also specified that we need to run a solid bare CU #8 with the MC cables. I sent a reply back questioning the solid bare #8. They state the #10 ground in the MC is not large enough to bond the rooftop equipment, it requires #8. They also state that solid wire is required if not in a raceway.
I think they are definitely confused as far as the solid wire is concerned. 250 requires grounding/bonding wires smaller that #6 to be protected. It doesn’t have any different protection requirements for solid vs stranded.
The sizing is something I need to investigate. I just received this request so have not reviewed the NEC yet but wanted to post here since I was on the forum now.
From seeing systems installed most installers seem to be all over the place for the ground sizing. I see many systems installed with #10’s for the DC and #10 ground in EMT. I see other systems with #10’s for the DC and #8 or #6 ground in the EMT.
I also question that if a larger ground is required, can it be run next to the MC cables. Generally the grounding conductor is required to be installed in the same raceway or cable sheath as the other conductors.
We are just completing the rough wiring of a single-family dwelling. The homeowner has a contract with a local PV company to install the PV system once the home is complete. The PV company and homeowner have requested that we prewire for the future PV system. We do this all the time by running a 1” EMT raceway from the roof to the future inverter location.
The way this home is designed with multiple roof levels it will be almost impossible to get between the array and inverter with EMT. The homeowner prefers not to see any exposed wiring on the roof.
I just received info from the PV company that they want us to run (2) 10-4 MC cables for 2 strings since EMT is not practical. The also specified that we need to run a solid bare CU #8 with the MC cables. I sent a reply back questioning the solid bare #8. They state the #10 ground in the MC is not large enough to bond the rooftop equipment, it requires #8. They also state that solid wire is required if not in a raceway.
I think they are definitely confused as far as the solid wire is concerned. 250 requires grounding/bonding wires smaller that #6 to be protected. It doesn’t have any different protection requirements for solid vs stranded.
The sizing is something I need to investigate. I just received this request so have not reviewed the NEC yet but wanted to post here since I was on the forum now.
From seeing systems installed most installers seem to be all over the place for the ground sizing. I see many systems installed with #10’s for the DC and #10 ground in EMT. I see other systems with #10’s for the DC and #8 or #6 ground in the EMT.
I also question that if a larger ground is required, can it be run next to the MC cables. Generally the grounding conductor is required to be installed in the same raceway or cable sheath as the other conductors.