[RE-wrenches] Transformerless inverter conversion

[William Miller]

Friends:



Thanks to all of you for your valuable input on the repowering project I am
researching.  I am learning a lot in the process and generating more
questions as I proceed.  Here is are questions that came up, and if any of
you have insight, I would love to hear it:



1.   Array OCPD/disconnecting.  The existing array has fuses in the
positive leads only.  If we were to upgrade to transformerless inverters,
will we be required to install OCPD in the negative leads as well?  (In
researching this I came upon this entry in 2017 NEC 690.9: *Informational
Note: Due to improved ground-fault protection required in PV systems by
690.41(B), a single overcurrent protective device in either the positive or
negative conductors of a PV system in combination with this ground-fault
protection provides adequate overcurrent protection.*)

*2.   *In the 2014 NEC when installing Ungrounded PV systems, the following
requirement appeared in 690.35:  *Conductors listed and identified as PV
wire installed as exposed, single conductors…*  What happened to 690.35,
and can I now use USE-2 on transformerless inverter installations?



Thanks in advance.



William Miller



Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985
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