PV system labeling requirements

Status
Not open for further replies.
A

apu

Member
Location
Springfield, NJ USA
It was more economical to contract out the solar install than reallocate my usual manpower or hire extra help to put the 125 panels on the roof and run all the wiring. And I'm happy with the workmanship. My only question is with the labeling they did. Am I misreading what the NEC (2014) requires?

On the two service disconnects (A & B in the attached drawing), they attached a label indicating that "terminals on both the line and load sides may be energized in the open position." That seems to be based on NEC 690.17(e) "Where all terminals of the disconnecting means may be energized in the open position, a warning label shall be mounted on or adjacent to the disconnecting means." Except, I don't see how this applies as the PV system line taps are ahead of the disconnect. If the load side is energized in the open position, there is a serious system fault that needs to be fixed. Just reading that label would lead me to believe it is a normal condition that doesn't need to be remedied.

They put that same label on the two main panels (C & D) (but not on the transfer switch or any of the five sub-panels). They also added "system is backfed" labels to both main panels and an "Inverter output connection. Do not relocate this overcurrent device" label on Panel C (but not D). But there is no PV connection to C or D (except via the line taps ahead of A & B) and no OCPD was added to Panel C.

I'm all for safety. And I'm okay with the more generic "solar electric system connected" and "turn off PV AC disconnect before working on this panel" labels downstream of the main disconnects. A "dual power source" label (not installed) would even be appropriate. But, from my reading of the NEC and just general common sense, I find these other labels misleading. Maybe they need them for their typical install, but they don't seem to apply here.

If I was coming in to work on the electrical system and wasn't here for the solar install, I'd be looking for what else I need to de-energize before working on the system instead of just throwing the disconnect, doing my job, and moving on with my day. And isn't the point of the labels to make sure anyone that comes in after I'm gone understands what they are looking at?

I'm reading 690.17(e) and 705.12(d); what am I missing?
 

Attachments

  • SolarSystem.jpg
    SolarSystem.jpg
    14.2 KB · Views: 11
You're not missing anything. Either the installers or the inspectors didn't know what they were doing. I see this a fair amount: inspectors sometimes don't really understand how these systems work, they just know there's supposed to be labeling and seeing a lot labels makes them feel comfortable. Likewise, installers try to make it seem like they've been thorough by slapping all the stickers in their kit somewhere on the equipment, without actual regard to what they say and how it applies. Sometimes the differences affecting whether a label applies are subtle and I can understand how a lack of training can explain it. Your case seems fairly over-the-top though, with just about all the stickers in error.

I particularly hate that "Terminals on both line and load..." label. And I really hate it when an inspector who doesn't understand how utility interactive inverters work makes me slap them all over the place. But I've had it happen several times.

Here's where that label is appropriate:

1) Where it disconnects a system with stand-alone operation capability from the utility. If the system doesn't have batteries, as most don't, then this situation doesn't apply.

2) A DC disconnect that disconnects PV source or output circuit from another source or output circuit to which it is paralleled. e.g. disconnects at combiners or recombiners, typically for large systems with a single central inverter.

3) Sometimes I stick it on string inverters where there's just a DC disconnect and if you throw the switch and open the cover you still have hot DC and AC from both directions. The wording isn't precisely correct but it is a more or less appropriate warning to be aimed at someone who knows enough to make bad assumptions but not enough to make good ones.
 
I see the WARNING LINE AND LOAD SIDES MAY BE ENERGIZED ON AC disconnects all the time. I also see it on micro-inverter systems.
There is no need.
Most common labeling mistake I see.

It actually refers most often to the fact that string inverters have capacitors inside them on their DC (not AC!) inputs. Hence, if you shut off DC power between array and inverter - i.e. "line and load sides" - then capacitors will remain energized. For up to 5 minutes on the inverter side. And indefinitely on the array side.

And so it goes on DC disconnects, not AC.
 
Last edited:
"Inverter output connection. Do not relocate this overcurrent device" that label is to ensure the PV breaker is located at the opposite end of a busbar from the utility feed (line side) to that busbar.

Sounds like it really does NOT serve any purpose if there isn't even an OCPD in that panel.
 
Zee said:
I see the WARNING LINE AND LOAD SIDES MAY BE ENERGIZED ON AC disconnects all the time. I also see it on micro-inverter systems.
There is no need.
Most common labeling mistake I see.

It actually refers most often to the fact that string inverters have capacitors inside them on their DC (not AC!) inputs. Hence, if you shut off DC power between array and inverter - i.e. "line and load sides" - then capacitors will remain energized. For up to 5 minutes on the inverter side. And indefinitely on the array side.

And so it goes on DC disconnects, not AC.
Click to expand...

I don't think it really is a mistake to include that warning as a matter of routine, or as a matter of unifying the text among all disconnects in the system.
 
Carultch said:
I don't think it really is a mistake to include that warning as a matter of routine, or as a matter of unifying the text among all disconnects in the system.
Click to expand...

Why is unifiying text across varied equipment with different operating characteristics a goal?
Color scheme, format etc...... sure.....whenever possible

The label on an AC DISCO would be a warning against a threat that is non existent.
UL1741.

So many labels already in pv......it is possible additional labels actually distract from the real dangers where labels do warn us.
 
Zee said:
So many labels already in pv......it is possible additional labels actually distract from the real dangers where labels do warn us.
Click to expand...

Yeah, it's a 'boy who cried wolf' situation, among other things. Say a seasoned solar service guy gets so used to ignoring those improperly applied labels, then comes across a system that has battery backup...
I think labels should be accurate.
 
The LINE AND LOAD label is so commonly stuck on AC disconnects around here that I have inspectors asking me for it....even where there is NO requirement or reason for it. (on a gridtie-only inverter output circuit).
 
Zee said:
"Inverter output connection. Do not relocate this overcurrent device" that label is to ensure the PV breaker is located at the opposite end of a busbar from the utility feed (line side) to that busbar.

Sounds like it really does NOT serve any purpose if there isn't even an OCPD in that panel.
Click to expand...

That's the one that got me looking at all the others more closely. But when the installers are just doing "what the boss said" and the boss isn't onsite, you're left scratching your head.

Thanks everyone for your feedback.
 
Status
Not open for further replies.
Top