Wallace:
William is correct, a PV System is NOT a SDS.
If you're installing a "TL" or transformerless string inverter, a DC GEC
from the inverter is NOT required, only a properly sized EGC.
With Micro-inverters, if the PV+ or PV- has a ground reference in the
micro-inverter, such as an Enphase M215, then a properly sized combined
EGC/GEC is needed.
Newer micro-inverters, such as the Enphase M250, are internally
transformerless so a combined EGC/GEC is NOT needed, only a properly
sized EGC.
Module and rail bonding requires a bonding device listed for the
purpose, or a racking/module system that has been listed as compliant to
the new UL standard.
You can "upsize" the EGC if desired to reduce its impedance for
lightning and surge protection.
Regards,
Gary Willett
Icarus Solar
On 11/9/13, 5:08 PM, William wrote:
W:
A string inverter does not constitute a separately derived system unless it is
transformer isolated. The recreating of the neutral is what creates an SDS.
Your GEC, if required, stops at the inverter. It is not always required, i.e.
Enphase M250.
William Miller
On Nov 9, 2013, at 1:53 PM, "Wallace W. Weeks" <[email protected]> wrote:
Wrenches,
On a recent install I've come across a question I would like to get your
thoughts on.
In regards to running a GEC on a "separately derived power system", more
specifically A single phase 600 v residential PV system with a string inverter.
From my past experience and building from approved plansets throughout the bay
area and Monterey Counties. I have always pulled a #10 ground with my DC
conductors.
A recent conversation sparked The idea a local jurisdiction wanted a GEC (minimum #
8 AWG In conduit & #6 bare free air) pulled from the roof to the inverter ?
Also #6 bare bonding the rails ?
Furthermore The GEC coming from the array shall not be permitted in FMC? The
scenario was transitioning from EMT to FMC in an attic.
Referencing and potentially misinterpreting
250.64 B, It does seem to exclude FMC from approved means of protection ?
My questions are as follows.
-Is it a common requirement to bond rails with # six bare & run a GEC from the
roof to the inverter ?
-Why would the transition from EMT to FMC not be acceptable because the GEC is
in the raceway ? when In a scenario that is free from damage. For example in
attic ?
Thank you for your clarification on these topics.
Cheers-W.W.W
Sent from W.W.W'S iPhone
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