Chasing prefabricated line cord through a protective conduit on a roof?

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brycenesbitt

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This question relates to running outdoor electrical conduit through a protective chase on a flat roof. Specifically, 240VAC 12/4 flexible outdoor rated cord manufactured by Enphase Energy for a microinverter solar installation.

The need is to build a physically protective chase between rows to avoid a trip hazard and avoid leaves piling up.

Option A: a junction box at both ends, standard metal conduit a few inches off the ground, pulling 12 gauge wires.
Option B: run a hunk of redwood or U-channel to support the cord. Tack the cord to the redwood/U-Channel.
Option C: Chase the flexible 12/4 cord through conduit.

A local electrician vaguely said that option C was not code compliant, that the insulation would need to be stripped first, and that the conduit would rust out. I'm writing to ask if there's any code basis for that assertion. And if conduit is used, would the conduit fill requirements need to be met based on the capacity of the panels or on the capacity of the wires?
 
Conduit fill requirements are purely mechanical and do not depend on what the wires are carrying.
Note that for a given wire gauge PV wire has a larger diameter because of its thicker insulation.
You will calculate the fill based on the outer diameter of the cable you use.
I do not see any code reason prohibiting C, but you will have to use a higher temperature when figuring allowed ampacity.
The ampacity required will be based on the total inverter output, not the AC breaker size it connects to.
 
@GoldDigger are you sure about the ampacity?

In normal operation the maximum amps is the maximum output of the inverters.

If a defect arises in an inverter at night, current could flow "backwards" through the disconnect OCPD, to the defective inverter. That current could be as high as the breaker allows.
 
brycenesbitt said:
@GoldDigger are you sure about the ampacity?

In normal operation the maximum amps is the maximum output of the inverters.

If a defect arises in an inverter at night, current could flow "backwards" through the disconnect OCPD, to the defective inverter. That current could be as high as the breaker allows.
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OK, a valid point.
I will still assert that the adjusted and corrected ampacity need only reflect the inverter output, although the base ampacity of the wire should be greater than the next smaller breaker size.
But I welcome other opinions.
Like whether the fault current should be considered continuous.... :)
 
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