DC Source Circuits and AC in same raceway

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jbl

Member
Location
Portsmouth, Ohio
690.4(B) says that PV Source or Output circuits shall not be installed in the same raceway, etc.........of other systems.
My question is this: I have an installer with a ground mount system. It has 2 separate racks, separated by approx 20 ft. He only installed (1) conduit between the racks and needs to get an AC feed to an inverter as well as a PV Source Circuit in this conduit. (3" PVC installed underground). Seeing that the inverter output circuit is still part of the "PV System", is this permissible to install the AC and DC circuits together in this conduit?
:?
Thanks!
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
It's a grey area, in my opinion.. I've passed an inspection with source circuits and the inverter output circuit in the same raceway, but I sort of think the inspector gave it to us when he could have not given it. The 2011 code says "PV source and PV output circuits shall not be contained in the same raceway, box ...[etc.] as conductors [etc.] of other non-PV systems..." (unless there's a partition, but you're talking about a conduit so that's irrelevant).

Is the inverter output circuit part of the PV system, or is it a non-PV part of the AC distribution system? An argument could be made either way, I think.

If you group and label everything your inspector may say it's okay. Or he may not, and in that case I don't think you'll have an argument that can change his mind.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
It's a grey area, in my opinion.. I've passed an inspection with source circuits and the inverter output circuit in the same raceway, but I sort of think the inspector gave it to us when he could have not given it. The 2011 code says "PV source and PV output circuits shall not be contained in the same raceway, box ...[etc.] as conductors [etc.] of other non-PV systems..." (unless there's a partition, but you're talking about a conduit so that's irrelevant).

Is the inverter output circuit part of the PV system, or is it a non-PV part of the AC distribution system? An argument could be made either way, I think.

If you group and label everything your inspector may say it's okay. Or he may not, and in that case I don't think you'll have an argument that can change his mind.
I agree. The safe thing to do would be to run separate conduits.
 

SolarPro

Senior Member
Location
Austin, TX
This has been a gray area. The proposed language for NEC 2014 is more clear:

690.31 Methods Permitted

(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. [italics added for emphasis]


This clarifies that the CMP does indeed want the inverter output circuits in a separate conduit from the PV source or PV output circuits.
 
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jbl

Member
Location
Portsmouth, Ohio
Thanks for the info. And yes, the proposed language will definitely clear this up. Unfortunately the installer is going to try his luck with leaving them in one conduit. I think he will have a good argument based off of the 2011 code. I have Mike Holts book on PV Systems in the 2011 Code. He shows an example in the book and he says "allows" these conductors in the same raceway. Hopefully it passes and the installer will not be hand digging another 50ft trench. Thanks again for all the input.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Thanks for the info. And yes, the proposed language will definitely clear this up. Unfortunately the installer is going to try his luck with leaving them in one conduit. I think he will have a good argument based off of the 2011 code. I have Mike Holts book on PV Systems in the 2011 Code. He shows an example in the book and he says "allows" these conductors in the same raceway. Hopefully it passes and the installer will not be hand digging another 50ft trench. Thanks again for all the input.
Why doesn't the installer simply ask the AHJ whether it will pass or not?

Of course, the rigor of inspection varies widely between jurisdictions. I had one electrical inspection last all of about two minutes. The inspector put DVM probes on the inverter side of the AC disco with the switch on, turned the switch off and saw the voltage drop to zero. Inspection over. I had another inspector ask me if a Sunny Boy 8000 was a microinverter.

Some inspectors, though, go over the installation in great detail.
 

Jubathoph

Member
Location
LA
It is compliant

It is compliant

If I recall correctly, NEC300.3 allows you to run DC and AC conductors in the same raceway provided all are under 600V and all wire is rated at 600V. The handbook specifically talks about PV.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
If I recall correctly, NEC300.3 allows you to run DC and AC conductors in the same raceway provided all are under 600V and all wire is rated at 600V. The handbook specifically talks about PV.

Yeah, but then 690.4(B) says there has to be this partition between PV source and output conductors and 'other systems'.
 

Jubathoph

Member
Location
LA
Inverter output conductors are part of the PV system. The handbook clarifies the intent of 690.4B stating, "Conductors directly related to a specific PV system, such as those in DC and AC output power circuits, may be contained in the same raceway as PV source and output conductors providing they meet the requirements of 300.3C."

The point is you are not permitted to mix Photovoltaic AD and DC conductors with miscellaneous light fixtures, or branch circuits etc. but you ARE allowed to mix AC and DC in general and with PV in particular, as long as they are part of the Photovoltaic System.
 

SolarPro

Senior Member
Location
Austin, TX
Agreed. The explanatory text in the 2011 Handbook is a useful point of reference if you need to make a case for running inverter output conductors in the same raceway with PV source or PV output conductors. (Unfortunately, it looks like that case may be much more difficult to make under the 2014 Code—unless you can partition the raceway.)
 
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jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Physically, I don't think it makes any sense to allow PV circuits in the same raceway as inverter output circuits and not in the same raceway as any other line voltage AC circuits. It's either safe or it's not.

If the notion is to separate PV system components from everything else to make maintenance and troubleshooting safe, that makes some sense.

Seems like maybe the CMP isn't of one mind as to why it's doing what it's doing.
 
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