[RE-wrenches] PV GEC

[Gary Willett]

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" <w3solar at gmail.com> 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
>>
>>
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>>
>> Sent from W.W.W'S iPhone
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