690.47 (was enphase) [RE-wrenches]

[Mark Frye]

Ray,

NEC 2008 690.43, "...Equipment grounding conductors for the PV array and
structure....shall be contained within the same raceway or cable, or
otherwise run with the PV array circuit conductors when those circuit
conductors leave the vicinity of the PV array."
 
Mark Frye
Berkeley Solar Electric Systems
271 Vistamont Dr
Grass Valley CA 95945
(530) 401-8024
www.berkeleysolar.com 

-----Original Message-----
From: Dick Ratico [mailto:Richard.L.Ratico at VALLEY.NET] 
Sent: Sunday, June 15, 2008 11:39 AM
To: RE-wrenches at topica.com
Subject: Re: 690.47 (was enphase) [RE-wrenches]


Ray & Mark,

This may prove controversial, but according to 2005 and 2008 NEC Article
250.134(B) Exception No. 2: 

"For dc circuits, the equipment grounding conductor shall be permitted to be
run separately from the circuit conductors."

Accordingly it would seem acceptable to bond the array GE and any and all
other GEs available, with the appropriate size of direct buried bare copper.
This bonding system would also serve as the dc equipment grounding
conductor, if one is not run with the circuit conductors. Doing this
eliminates the inductive grounding loop (but note that metal raceway, if
used, enclosing the dc cicuit conductors could also contribute to a loop),
and puts a lot of CU in the ground to help dissipate any surges. This also
reduces the likelihood of potential voltage differences between GEs, which
cause surges to travel over EGCs run with circuit conductors.

Regards,

Dick
Solarwind Electric
Bradford, VT


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