PV Inverter

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geochurchi

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Concord,NH
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Hi All, I was looking at a PV install inverter feed to the Meter/Main/12 circuit panel, the feed from the inverter is back feeding a QO240 breaker,although there is a Warning label on the cover but not on the breaker, is this legal, and is this a normal install?
Geo
 
geochurchi said:
Hi All, I was looking at a PV install inverter feed to the Meter/Main/12 circuit panel, the feed from the inverter is back feeding a QO240 breaker,although there is a Warning label on the cover but not on the breaker, is this legal, and is this a normal install?
Geo
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It could be, but there are several things to consider. What is the rating of the panel busbar? What is the rating of the MDP main breaker? What is the maximum current output of the inverter? Where is the backfed breaker - at the opposite end of the busbar from the main breaker, or elsewhere in the panel?
 
blkmagik21 said:
You need a warning label at the breaker. The NEC is very clear on this


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If you mean the one that says not to move the breaker, not necessarily. If the panel bus is qualified under 705.12(D)(2)(3)(a) or (c), the breaker can be anywhere on the bus and can be moved.
 
Just be aware that many POCO's require a visible disconnect between the breaker and the inverter. I really wonder why. I asked our linemen if they ever check to see if it's open before they work on the lines, and not one said he ever did, since they isolate, test and ground the line anyway before contacting it.
 
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PV Inverter

OK, 200 amp main,200 MDP,inverter back fed breaker is in top slots under the main,not sure what difference that makes,not sure what Art. 705 refers to.
Geo
 
The back fed breaker should be on the opposite side of the main. If the mains on top the backfed breaker should be on the bottom. Also in many cases depending on the bus rating you need to downsize the main breaker so not more than 200 amps can flow across the bus.


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geochurchi said:
OK, 200 amp main,200 MDP,inverter back fed breaker is in top slots under the main,not sure what difference that makes,not sure what Art. 705 refers to.
Geo
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In that case it is a violation. The 40A backfed breaker needs to be at the opposite end of the bus from the main breaker per 705.12(D)(2)(3)(b) and labeled "do not relocate this breaker".
 
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