But does directly burying individual wires constitute a raceway or cable method?To clarify a bit more, here is a portion of the response from a cable engineer:
... 690.31 states that ?All raceways and cable wiring methods included in this Code and other wiring systems and fittings specifically intended and identified for use on photovoltaic arrays shall be permitted? .... Nowhere in Article 690 are underground installations specifically mentioned.
Neither the language in 690 or 300.50 is perfectly clear. However, based on the language in 690.31, my position is that since our PV conductors are Listed for and ??specifically intended for use on photovoltaic arrays?? our customers should be able to direct bury the single conductors, even when the nominal system voltage is over 600 volts."
Call me skeptical. Photovoltaic arrays are not buried, so 'intended for use on PV arrays' doesn't imply suitability for burial. Is he saying their conductors are listed both as PV wire and as some type subject to 300.50(A)(1)? I've certainly never heard of a product that resembles this.However, based on the language in 690.31, my position is that since our PV conductors are Listed for and ??specifically intended for use on photovoltaic arrays?? our customers should be able to direct bury the single conductors..."
In the case of a PV system, it's unlikely that the metal sheath would act as a return path, since the GFDI is usually in the inverter. Fire dangers could potentially be worse if it did act as such. Not that that's anything but trivia as far as what the code allows.I am in agreement with you. I contend that the intent of 300.50 is personnel protection, should someone come into contact with the cable. The grounded metal sheath would provide a return path. Direct buried cables that are not protected with a ground return path are not in compliance. This is why PVC in earth would not be acceptable as well.
There is nothing special you need to do for 1000 volts and under. The MV requirements are for OVER 1000 volts.By following the NEC 2014, 310.10(F) and 300.5, can we install a 2kV PV (PV and RHW-2) wire (Circuit voltage is 1000V) in a PVC/IMC/RMC raceway 24" below grade? Can it also be directly buried 24" below grade? Or is there any other code that I have t follow? Thanks