- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Yes, we are not saying it makes sense but the NEC does appear to require that all insulation be the same voltage rating.
Photovoltaic question
- Thread starter shputnik
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ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
That's an EGC.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
It doesn't make sense at all, seeing as the metal conduit is grounded.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I agree
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Ok yeah it says what it says, but I can't imagine that is the intent. Anyway , I don't think we have "different systems" so I don't see that applying anyway
Just to be clear. There is no metal conduit....the 1000 volt DC conductors are in a cable tray that extends from one array to the other with the 600 volt insulated conductor bonding the tray and the racking....then from the racking to the combiner box ground bar.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I was agree that it was strange... I didn't pay any mind to conduit comment because it didn't matter anyway.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
You are fine. The EGC could be bare if you want.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
No issue.
And you are talking about an equipment grounding conductor. That's what the conductor bonding the racking and cable tray is called.
BradPV
Member
- Location
- North Carolina
- Occupation
- Residential PV Qualifier
The reference to 300.3(C) is for conductors of different systems and does not apply at all. As ggunn and jaggedben stated you ARE talking about the EGC and it CAN be bare so who cares if it is rated 600v send it.....
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
So, do we have the bizarre situation where if the conductor is bare, you're fine, but if you put insulation on it, now it has to be listed for 1,000 volts?
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Is that any different then if you run conduit, say emt, and have a 30 amp circuit then you don't need an equipment grounding conductor however, if you choose to run it then it must be rated 30 amps. You can't just run a 20 amp wire.So, do we have the bizarre situation where if the conductor is bare, you're fine, but if you put insulation on it, now it has to be listed for 1,000 volts?
I know it's not the same but it is a similar concept.
BradPV
Member
- Location
- North Carolina
- Occupation
- Residential PV Qualifier
What system are you using that is 1000v, I was assuming this to be residential due to the NEC references. And again be careful of the NEC headers when you are looking these up. The reference in 300.3 was from "Conductors of different systems". Do you in fact have different systems in this raceway? Most of my experience is in utility and we did not use PV grounding conductors which did drive us to use loom where it was exposed to sunlight (and to protect the conductors from the purlin edges). In residential I don't know of a system using 1000v other than the modules themselves.So, do we have the bizarre situation where if the conductor is bare, you're fine, but if you put insulation on it, now it has to be listed for 1,000 volts?
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
The OP specifically asked about 1,000 volts.
Even if you don't have different systems, the insulation has to be good for the voltage of the ungrounded conductors, right? You wouldn't use THHN on such a system.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
I run THWN-2 ground wires with 2000V PV wire all the time and I have never had an AHJ challenge it.
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
As a matter of practicality, it may make no difference, but THWN-2 is listed only to 600 volts. Is it technically a violation?
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
I know, and I don't think so. I think that if it were, someone would have brought it up. I have designed over 100 commercial PV systems in many jurisdictions, and some of them are real sticklers over fine points in the code.
BradPV
Member
- Location
- North Carolina
- Occupation
- Residential PV Qualifier
But, why does the voltage matter for the EGC? It just needs to be sized appropriately.....
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
That's the conventional wisdom, but I'm not sure I buy it. If you run emt as your EGC, and the circuit inside is on a 30A breaker, then if you have a #12 Cu green wire inside, I agree the green wire is not an adequately sized EGC. But that just makes it an extra green wire you felt like having that is bonded at both ends to the EGC; the EMT is still your EGC. What section prohibits that extra green wire?
Cheers, Wayne
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