[RE-wrenches] FW: 690.47D (revisited)

[Mark Frye]

Kelly,

If I read you right you are talking about two different things.  The EGC
running with the PV DC circuit conductors are just that,  EGC's and are
sized to the largest PV DC conductor. Applying 690.47D to these conductors
is incorrect.

There is a conductor running from the inverters to the main panel however.
Some have argued that this conductor is subject to 690.47D, #8 minimum. What
size conductor are you using here?

There was some discussion that the wire running from the inverter to the
main panel is not in fact the DC GEC, but rather a bonding jumper connecting
the inverter AC/DC systems to the DC GEC and that this wire need only be
sized to the inverter PV AC backfeed breaker. This same conductor also
serves at the EGC for everything on up to the array.


Mark Frye
Berkeley Solar Electric Systems
303 Redbud Way
Nevada City,  CA 95959
(530) 401-8024
www.berkeleysolar.com 

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Kelly
Keilwitz, Whidbey Sun & Wind
Sent: Thursday, June 04, 2009 5:34 PM
To: RE Wrenches listserve
Subject: [RE-wrenches] FW: 690.47D (revisited) 


All,
This issue was discussed here about a year ago, before most jurisdictions
had adopted the 2008 Code and AHJ's started interpreting it.

Our current situation is a residential, roof-mounted PV array, with not an
extraordinary distance to the existing AC GEC. The AHJ has NOT required the
"additional PV" GE, but IS requiring the extra GEC from the array to the
AC/DC GE, on the grounds of (690.47D) "The dc grounding electrode conductor
shall be sized according to 250.166" (i.e. #8 min). We have the standard EGC
inside the conduit, running with the PV DC circuit conductors.

Is there any "grounds" for this requirement? What are your AHJ's requiring?

Thanks,

Kelly Keilwitz, P.E.
Whidbey Sun & Wind, LLC
Renewable Energy Systems
NABCEP Certified PV Installer
WA Electrical Administrator #KEILWKM923RB
987 Wanamaker Rd.
Coupeville, WA, 98239
360.678.7131
sunwind at whidbeysunwind.com
WA Electrical Contractor #WHIDBSW920MS
WA General Contractor #WHIDBSW946M1