PV Source circuits from grounded and ungrounded system s in the same conduit

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Is there an issue with running the DC conductors for grounded and ungrounded systems in the same conduit. We are getting requests for expansions to older systems and can use the existing conduit for most of them.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Is there an issue with running the DC conductors for grounded and ungrounded systems in the same conduit. We are getting requests for expansions to older systems and can use the existing conduit for most of them.
I don't see an issue as long as all other conditions are met, i.e., derating for CCC's, conduit fill, no two wires having a voltage differential more than the rating of the insulation, etc.
 
I don't see an issue as long as all other conditions are met, i.e., derating for CCC's, conduit fill, no two wires having a voltage differential more than the rating of the insulation, etc.

PVC is rated at 600V, on the outside chance that a (+) grounded system conductor shorts to a (-) ungrounded conductor would there be a potential for greater than 600V?
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
PVC is rated at 600V, on the outside chance that a (+) grounded system conductor shorts to a (-) ungrounded conductor would there be a potential for greater than 600V?

Maybe in an extreme fluke case, but it's irrelevant because that's not how voltage to ground is defined.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
The code specifies elsewhere that the voltage to ground in an ungrounded source shall be considered to be the largest line to line voltage in the circuit.
Not that plus the highest other voltage to ground in the raceway.
 

pv_n00b

Senior Member
Location
CA, USA
All the conductors in a conduit have to be rated for the highest voltage conductor in the conduit (300.3(C)(1)). So if the old DC conductors have a lower rating than the new system the old conduits can't be reused.
 
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