120 % NEC rule and Panel labels

Status
Not open for further replies.
I

ING23

Member
Location
Las Vegas
Occupation
Site Survey Tech
I am figuring out how to pull some info of this panel label in order to comply with NEC 120 % rule . I think this bus rating is not 400 Amps and due there is no mention of BUS Rating ON THE LABEL I am assuming is 200 amp. Any Idea how to comply with 120% NEC rule ?
System Size is 15.2kW interactive and those photo attached are the Panel I am trying to connect the system
 

Attachments

  • 2.JPG
    2.JPG
    995.9 KB · Views: 70
  • 1.JPG
    1.JPG
    1,007.7 KB · Views: 69
You have some violations. Why are the service conductors entering the panel without conduit? Other areas have wires coming thru a nm connector but you can't see the NM
 
Dennis Alwon said:
Why are the service conductors entering the panel without conduit?
Click to expand...
If you're referring to the wires on the line side of the 200A breakers, those are factory installed conductors coming from the meter section to the left.

As to the OP, if you are trying to interconnect (2) 7.6 kW inverters, you can't do that with a single interconnection using the 120% rule. You effectively have (2) 200A services. So you could interconnect (1) 7.6 kW inverter at the bottom of the bus shown, using the 120% rule. The other 7.6 kW inverter would need to be interconnected on the other 200A service. That could be done under the 120% rule if the other 200A service supplies a 200A panel.

Or, since the upper 200A service supplies a 200A feeder, you could do a single 15.2 kW feeder interconnection by intercepting that feeder.

Cheers, Wayne
 
I happen to have confirmed with Square-D that the lower section load-side busbar on this particular meter main (SU3040D400CB) is 200A.

This is a common problem with 2x200A meter/mains that the busbar rating of the load-side panelboard component is not labeled. But it's always 200A so far as I've seen.
 
Dennis Alwon said:
You have some violations. Why are the service conductors entering the panel without conduit? Other areas have wires coming thru a nm connector but you can't see the NM
Click to expand...
I think its 320A a meter on the left that passes thru to the split buss were seeing.
but yeah on the bottom it looks like someone tan THHN thru a NM connector.
 
tortuga said:
I think its 320A a meter on the left that passes thru to the split buss were seeing.
but yeah on the bottom it looks like someone tan THHN thru a NM connector.
Click to expand...
320 amp meter base is based on continuous loads. That 400 amp meter base is good for 400 amps non-continuous.
 
I am not framiliar with that lug kit or how its installed, it is intriguing.
Another option could be to replace that top main breaker with a 200A breaker and set another 200A loadcenter to handle the 100A feeder and the ~65A of solar.
 
jaggedben said:
I had noticed the top breaker is only 100A.

Tortuga no need to replace the top breaker, better to leave as is.

Divert to a 200A panel and feed with the 100A breaker. New panel gets 100A breaker spliced to existing feeder, plus 80A solar breaker. All good.
Click to expand...

Absolutely. This is a simple one.

And you’d probably be ok to use a “vampire” style inline taps on the feeders feeding each breaker from the meter section; however, that’s a listed assembly so it could get rejected.

Your best bet is to simply use the 120% rule with what you’ve already got, 120%x200a rating=240-100a existing breaker=140a net backfeed, so 80a or 15kw should be no problem.

Remember to apply early, 15kw should only be a problem if your service happens to be fed by a 10kva tx from the utility and you’re the solo customer.
 
  • Like
Reactions: Zee
BackCountry said:
Your best bet is to simply use the 120% rule with what you’ve already got, 120%x200a rating=240-100a existing breaker=140a net backfeed, so 80a or 15kw should be no problem.
Click to expand...
Does not apply as the top breaker (which I hadn't realized is only 100A) does not have a busbar.

So the OP could interconnect 100A (after 125%) of PV via that 100A feeder, as long as the panel supplied by the 100A feeder has a main breaker. E.g. bring the PV conductors into the top section and splice to the 100A feeder. The PV conductors would need to satisfy a tap rule.

Jaggedben's proposal is a cleaner but requires an extra panel.

Cheers, Wayne
 
Status
Not open for further replies.
Top