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Monday, July 11, 2016
Question:
Hello, thank you for providing us the code question of the day. Nothing gets your mind focused in the morning like the code does!
The question I have is this – for a PV system, where does the PV part of the system end if you are connecting to a utility? Let’s say we have inverters feeding a common ac collector cable through step-up MV transformers, and the end of the ac collector is connected to the point of common coupling at the utility (substation). Does the ac collector still need to be considered part of the PV system and subject to the 125 % conductor ampacity requirement given in 690.8(B)(1)? The installation will not be owned nor operated by the utility.
It’s clear that the inverter output is still considered part of the PV system because of 690.8(A)(3). What is not clear is how far down the line we must go before we cross over to non-PV territory, and are no longer required to give ourselves an extra 125 % ampacity boost for conductors.
Thank you, Scott K
A
Answer:
Hey Scott thanks for your question and we are glad to help you focus. If you are interconnecting a PV system to a utility source then Article 705 also applies as stated in 690.3. Inverter system currents are considered to be continuous and the conductors and overcurrent devices must be at least 125 % as stated in 705.60(B). Even for non PV systems the 125% factor for continuous loads still applies as stated in 215.2 and 215.3.