String Wiring and DC conductors in same cable tray?

[Kevin Whitten]

Hey All,

My question is this: if I am using ladder tray with a cover on it, can I place dc string wiring in the same cable tray as the dc conductors coming from combiner boxes? Based off of 390.22, I would assume it's not a problem, however a colleague believes that we will need a divider in the cable tray to keep string wiring and dc conductors separate in the tray. I can't find where it says something like that in the code, so I'm second guessing myself. Does anyone know the answer to this question?

 

[69gp]

Hey All,

My question is this: if I am using ladder tray with a cover on it, can I place dc string wiring in the same cable tray as the dc conductors coming from combiner boxes? Based off of 390.22, I would assume it's not a problem, however a colleague believes that we will need a divider in the cable tray to keep string wiring and dc conductors separate in the tray. I can't find where it says something like that in the code, so I'm second guessing myself. Does anyone know the answer to this question?

No divider is needed as long as the insulation of the wiring is equal to the highest value of voltage for wiring

 

[Zee]

I can only say that you need a "partition" if there is AC and DC wiring together.
In your case: i do not know the answer.

 

[jaggedben]

Hey All,

My question is this: if I am using ladder tray with a cover on it, can I place dc string wiring in the same cable tray as the dc conductors coming from combiner boxes? Based off of 390.22, I would assume it's not a problem, however a colleague believes that we will need a divider in the cable tray to keep string wiring and dc conductors separate in the tray. I can't find where it says something like that in the code, so I'm second guessing myself. Does anyone know the answer to this question?

Did you mean 392.22?

I definitely don't think there's a need for a divider. Perhaps your colleague is confused over 690.4(B) but that only applies to PV circuits with non-PV circuits, which is not your situation. That's the only section I'm aware of that requires a partition.

 

[Kevin Whitten]

I actually found the section of code that talks about this situation:

690.31(B) Identification and Grouping. PV source circuits and PV output circuits shall not be contained in the same raceway, cable tray, cable, outlet box, junction box, or similar fitting as conductors, feeders, branch circuits of other non-PV systems, or inverter output circuits, unless the conductors of the different systems are separated by a partition.

My new question is now this: does the NEC consider PV output circuits as conductors in this code section? The definition they give for PV output circuits' is "circuit conductors between the PV source circuit(s) and the inverter or dc utilization equipment", yet 690.31(B) seems to not consider it as conductors.

 

[Kevin Whitten]

Did you mean 392.22?

I definitely don't think there's a need for a divider. Perhaps your colleague is confused over 690.4(B) but that only applies to PV circuits with non-PV circuits, which is not your situation. That's the only section I'm aware of that requires a partition.

I did mean 392.22, I apologize. I did find the section in 690 this morning which talks about grouping of pv circuits, which I replied with in this forum.

 

[jaggedben]

I actually found the section of code that talks about this situation:

690.31(B) Identification and Grouping. PV source circuits and PV output circuits shall not be contained in the same raceway, cable tray, cable, outlet box, junction box, or similar fitting as conductors, feeders, branch circuits of other non-PV systems, or inverter output circuits, unless the conductors of the different systems are separated by a partition.

My new question is now this: does the NEC consider PV output circuits as conductors in this code section? The definition they give for PV output circuits' is "circuit conductors between the PV source circuit(s) and the inverter or dc utilization equipment", yet 690.31(B) seems to not consider it as conductors.

What code precisely is that? Because in the 2011 NEC that's 690.4(B), but the phrase "or inverter output circuits" does not appear.

A PV output circuit is a DC circuit, usually referring to the combined output of more than one source circuits (strings). PV source and output circuits will have conductors, yes, but I don't see why you're asking that. I think the purpose of this section is protect personnel from confusion between circuits that are energized by the sun and can't be easily turned off, vs. other circuits. Again, as long as your cable tray (or other raceway) contains only PV source circuits and PV output circuits you do not need a partition and are not violating any other code.