adunbar
Member
- Location
- lowell, ma
The Solar industry is moving toward designing ground mounted PV systems with 1500V dc solar modules. The requirements in NEC 2017 article 300.50(A)(3) require underground nonshielded cables rated over 1000V be installed in conduit encased in not less than 3" of concrete. This would require all our underground PV source circuits to be encased in concrete.
If I look at article 300.50(A)(2), it permits nonshielded single conductor cables up to 2000V to be direct buried in industrial establishments if listed for direct burial.
Our PV systems are installed behind a fence, serviced only be qualified persons. Our interpretation is that our 1500V dc source circuits do not need to be concrete encased when installed underground, in conduit, behind a fence.
Please let me know if you agree with our interpretation as we made a similar argument when we moved to 1000Vdc systems during previous code cycles and the code spoke to over 600V. I appreciate any input you can provide as we expect to start designing 1500V systems in the next few months and the cost of encasement would be huge.
If I look at article 300.50(A)(2), it permits nonshielded single conductor cables up to 2000V to be direct buried in industrial establishments if listed for direct burial.
Our PV systems are installed behind a fence, serviced only be qualified persons. Our interpretation is that our 1500V dc source circuits do not need to be concrete encased when installed underground, in conduit, behind a fence.
Please let me know if you agree with our interpretation as we made a similar argument when we moved to 1000Vdc systems during previous code cycles and the code spoke to over 600V. I appreciate any input you can provide as we expect to start designing 1500V systems in the next few months and the cost of encasement would be huge.