Raceway

Moorecam

New User
Location
USA
Occupation
Solar Electrician
Hey guys! I want to confirm that's it okay to run AC & DC of the same PV system in the same raceway. Ex. Trough
Art. 690.31(B) 1&2
Art. 300.3 (C)1
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Pretty sure it's not okay to mix them, especially if there are no optimizers involved. In a trough you may be able to use a partition. What code cycle are you on?
 
  • Like
Reactions: Zee

Carultch

Senior Member
Location
Massachusetts
In the '17 Code 690.31(B) spells out that they can not be.

The rule first began in 2014. Prior to 2014, you were allowed to mix them in the same trough as long as you bundled them and identified them. It still allows a partition to make use of the same wireway for both.
 
  • Like
Reactions: Zee

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
The rule first began in 2014. Prior to 2014, you were allowed to mix them in the same trough as long as you bundled them and identified them. It still allows a partition to make use of the same wireway for both.
The rule has existed since before the 1999 code. In the 2011 and earlier codes the rule was found in 690.4(B). In 2014 code that language was relocated to its current location in 690.31(B). Below is the 1999 language.
690-4
(b) Conductors of Different Systems. Photovoltaic source circuits and photovoltaic output circuits shall not be contained in
the same raceway, cable tray, cable, outlet box, junction box, or similar fitting as feeders or branch circuits of other systems,
unless the conductors of the different systems are separated by a partition or are connected together
 

mwm1752

Senior Member
Location
Aspen, Colo
PV source circuits and PV output circuits (Photovoltaic System DC Circuit.)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, (your AC circuit) unless the conductors of the different systems are separated by a partition.
 
  • Like
Reactions: Zee

ceb58

Senior Member
Location
Raeford, NC
In the '17 Code 690.31(B) spells out that they can not be.
Is there any code section that permits it? Case in point 1- 3/4 inch EMT with 4 - 120vac branch circuits from new back up panel to existing panel where the branch circuits will be tied on for the chosen back up loads AND the 2 DC conductors that charge the battery bank from the solar inverter?
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Is there any code section that permits it? Case in point 1- 3/4 inch EMT with 4 - 120vac branch circuits from new back up panel to existing panel where the branch circuits will be tied on for the chosen back up loads AND the 2 DC conductors that charge the battery bank from the solar inverter?

Battery conductors may be different from pv source and output circuits. Depends on more details of how your system really works. For example are there optimizers or a charge controller in between the panels and this raceway.
 

SolCon

Member
Location
United States
Occupation
Designer
@jaggedben : I've seen the 'if you have optimizers' mentioned before here. Is there something in the NEC 2017 code that allows mixed DC and AC from the same inverter system if the DC strings in the same raceway have optimizers? I have PV Panels with Tigo TS4-A-O optimizers which have short circuit and rapid shutdown features on each PV panel creating DC strings of from 350 to 450VDC. Would I still have to partition the high voltage DC coming from the optimized strings from the AC output of my inverter? I currently have them both entering a 8x8x48" wiring trough as I've seen all the time in videos and documentation and those were not partitioned inside the trough. Thanks for any advice.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
You have this, however art 690 would supercede art 300

(C) Conductors of Different Systems.
(1) 1000 Volts, Nominal, or Less. Conductors of ac and dc
circuits, rated 1000 volts, nominal, or less, shall be permitted to
occupy the same equipment wiring enclosure, cable, or raceway.
All conductors shall have an insulation rating equal to at
least the maximum circuit voltage applied to any conductor
within the enclosure, cable, or raceway.
Secondary wiring to electric-discharge lamps of 1000 volts or
less, if insulated for the secondary voltage involved, shall be
permitted to occupy the same luminaire, sign, or outline lighting
enclosure as the branch-circuit conductors.
 

SolCon

Member
Location
United States
Occupation
Designer
@Dennis Alwon Thanks for the quick reply, however I'm still not certain of your answer. Are you saying that because I have optimizers and my wire insulation is rated higher than any voltage that might be in the raceway (600V THHN) I'm ok to mix and match AC and DC conductors and do not need a partition? You say article 690 supersedes 300 and bout you quote 300 so I'm guessing you are saying that "690.31(B) 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." means I need to create a partition. That being said, I'm still confused by several comments about optimized DC circuits, such as those from the Tigo Optimizers which include disconnects and short circuit protection in them.

If I do need a partition, somebody in another post mentioned split loom as a suitable partition, as the intent is to create an electrically insulating barrier if the wiring insulation fails. This would be easiest for me if it complies with code as a 'partition'.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
You need a partition.

If you are under the 2020 NEC, it is clear. That version of 690.31(B) refers to separation for "PV system DC circuits" which are defined at the beginning of the article to include DC-to-DC circuits.

For the 2017 NEC, it is a little less clear. That version of 690.31(B) refers to separation for "PV source circuits and PV output circuits." And the definition of "Photovoltaic Output Circuit" is "Circuit conductors between the PV source circuit(s) and the inverter or dc utilization equipment," which certainly sounds like it would include the conductors between the DC-DC converter and the inverter.

The only thing that muddies the waters is that Figure 690.1(a) has a label pointing to a conductor that says "PV or DC-DC converter output circuit." Which would suggest that the circuit could be one or the other but not both. But since that would be in contradiction to the plain language of the definition, I would say you still need a partition under the 2017 NEC.

Cheers, Wayne
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
@Dennis Alwon Thanks for the quick reply, however I'm still not certain of your answer. Are you saying that because I have optimizers and my wire insulation is rated higher than any voltage that might be in the raceway (600V THHN) I'm ok to mix and match AC and DC conductors and do not need a partition? You say article 690 supersedes 300 and bout you quote 300 so I'm guessing you are saying that "690.31(B) 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." means I need to create a partition. That being said, I'm still confused by several comments about optimized DC circuits, such as those from the Tigo Optimizers which include disconnects and short circuit protection in them.

If I do need a partition, somebody in another post mentioned split loom as a suitable partition, as the intent is to create an electrically insulating barrier if the wiring insulation fails. This would be easiest for me if it complies with code as a 'partition'.


The only reason I posted that was someone had asked if there was somewhere in the code that spelled it out. Art. 300 spells it out but chapters 1-4 can be overridden by the other chapters. So if art 300 says you can mix ac/dc and 690 says you can't then you can't mix them.
 

SolCon

Member
Location
United States
Occupation
Designer
Thanks All- OK now it seems like a partition is necessary the next question is what to make the partition of – I assume it doesn’t have to be some type of UL approved enclosure or material – therefore would some split loom plastic tubing work to jacket the DC wiring? Or does it need to be more substantial like metallic flex conduit? And how sealed does it need to be? Can there be minor gaps?
 
You need a partition.

If you are under the 2020 NEC, it is clear. That version of 690.31(B) refers to separation for "PV system DC circuits" which are defined at the beginning of the article to include DC-to-DC circuits.

For the 2017 NEC, it is a little less clear. That version of 690.31(B) refers to separation for "PV source circuits and PV output circuits." And the definition of "Photovoltaic Output Circuit" is "Circuit conductors between the PV source circuit(s) and the inverter or dc utilization equipment," which certainly sounds like it would include the conductors between the DC-DC converter and the inverter.

The only thing that muddies the waters is that Figure 690.1(a) has a label pointing to a conductor that says "PV or DC-DC converter output circuit." Which would suggest that the circuit could be one or the other but not both. But since that would be in contradiction to the plain language of the definition, I would say you still need a partition under the 2017 NEC.

Cheers, Wayne
Interesting, I was not aware of that change. It was always a bit of a pet peeve of mine when people would say "you can't have AC and DC in the same raceway" because the PV source circuits part would typically get glossed over.
 

SolCon

Member
Location
United States
Occupation
Designer
Hello All

Now that we've established that a 'partition' is necessary according to NEC 2017 and later, can folks chime in about what would be a suitable partition that would pass inspection for NEC 2017? Would simply wrapping the DC circuits and other non-solar wires in a Flame Retardant Polypropylene Split Wire Loom Tubing work? Or does at have to be more substantial, like metal plates, flexible metallic or non-metallic conduit, etc?

Can there be small gaps in the partitions, like when the wiring enters and exits the trough? In a wiring trough that is put bellow the inverter for all it's wiring and in the examples I have seen these partitions are never used which led me to believe that the partition didn't need to be there.

Attached in an example of a wiring trough below some solar inverters that has a mix of PV DC, Battery DC, battery thermometer wires, CT sensor wires that measure power from the main power coming in. I also assume according to NEC code that the insulation on these non-AC and DC control wiring needs to be rated with at least the maximum voltage I might see, so this would be 500V or so. I'm pretty sure there are no markings on these control wires for insulation rating so how would these pass code?

Thanks all for any advice here.
 

Attachments

  • Sol-Ark wiring trough raceway example.jpg
    Sol-Ark wiring trough raceway example.jpg
    611.8 KB · Views: 9

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
The word partition is not defined in the NEC to my knowledge. Looking at the way it's used and the general meaning, I would expect it to mean a solid rigid barrier that divides the entire enclosed space into two separate enclosed spaces.

Having said that, it's worth noting that 690.31(B) covers only the PV system DC circuits. I don't know if there's a separate article that would require separation for the battery DC conductors, and what they would need separating from.

As to your picture, based on the description, it obviously violates 690.31(B). The PV system DC circuits should be in a separate trough. Or if they connect to only one or two of the EMT risers coming out of the trough, I would think they could be run in conduit within the trough to provide the requisite separation. [Although conduit outside the trough would seem to be cleaner.]

Cheers, Wayne
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Hello All

Now that we've established that a 'partition' is necessary according to NEC 2017 and later, can folks chime in about what would be a suitable partition that would pass inspection for NEC 2017? Would simply wrapping the DC circuits and other non-solar wires in a Flame Retardant Polypropylene Split Wire Loom Tubing work? Or does at have to be more substantial, like metal plates, flexible metallic or non-metallic conduit, etc?

Can there be small gaps in the partitions, like when the wiring enters and exits the trough? In a wiring trough that is put bellow the inverter for all it's wiring and in the examples I have seen these partitions are never used which led me to believe that the partition didn't need to be there.

Attached in an example of a wiring trough below some solar inverters that has a mix of PV DC, Battery DC, battery thermometer wires, CT sensor wires that measure power from the main power coming in. I also assume according to NEC code that the insulation on these non-AC and DC control wiring needs to be rated with at least the maximum voltage I might see, so this would be 500V or so. I'm pretty sure there are no markings on these control wires for insulation rating so how would these pass code?

Thanks all for any advice here.
You and your AHJ are on your own.

Personally the split loom seems fine to me but it might depend on the situation.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
PV source circuits and PV output circuits (Photovoltaic System DC Circuit.)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, (your AC circuit) unless the conductors of the different systems are separated by a partition.
I have seen that, but what is the purpose of the partition? Is it to provide extra insulation between the wires or is it just so they won't get mixed up and you can tell one source from the other when you open the gutter??
 
Top