[RE-wrenches] PV Wiring methods

[Glenn Burt]

Hi August,

 

The handbook has a note regarding this under 690.31(B):

 

. Long runs of separated conductors (with loop inductance and distributed
capacitance) and the resulting long-time constants in dc circuits may result
in improper operation of overcurrent devices. It is suggested that, wherever
possible, both positive and negative conductors of each circuit and the
equipment grounding conductor be routed as close together as possible to
minimize the circuit time constant. The smaller loop resulting from the
close routing also decreases induced currents from nearby lightning
strikes..

 

-Glenn

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of August Goers
Sent: Tuesday, November 19, 2013 12:39 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] PV Wiring methods

 

Hi All -

 

On a related note, I've become good friends with some of the inspectors in
San Francisco and they called me yesterday with a question. Is it okay to
run individual DC conductors through EMT for wire management purposes? We
have always run paired positive and negative conductors in conduit so the
question had never occurred to me. Obviously, you have to bond both ends of
the conduit if it is over 250 v. I know that AC would have induction issues
with running individual conductors but I'm not sure with DC.

 

Thanks,

 

August

 

 

August Goers

Principal

Luminalt Energy Corporation

o: 415.641.4000

m: 415.559.1525

www.luminalt.com

 

 

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of William
Miller
Sent: Monday, November 18, 2013 11:33 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] PV Wiring methods

 

Bill:

 

There is no need to stuff MC4 cables into standard conduit.  You can either
slot the pipe using our easy method or install bulkhead type connectors.
The connectors are readily available.  I get them from PV Cables in Northern
California..

 

Wire routing problems and some solutions can be found on our web-site:

 

http://millersolar.com/MillerSolar/practices/PV_wiring/_PV_Wiring2.html

 

Since the industry won't provide wire management solutions, we are making
our own.  Questions:  Just write or call.

 

William Miller

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of frenergy
Sent: Thursday, November 14, 2013 7:46 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] PV Wiring methods

 

William, Bill....from another Bill,

 

        Two things:  For the rest of us (maybe it's just me?!) that's still
trying to figure out how (or why) to stuff a MC4 connector into conduit and
my hesitation in using SS wire ties for fear of the sharp edges cutting or
chaffing into cables, I'm open for advice. Any wire I use on the roof is
rated for that type of service and I have some off-grid systems that have
been in the sun for some 25 years where the wire still looks nearly new even
when flexing it to look for checking/cracks.  It seems the wire/insulation
can take it, thus it seems like the key to "wire management is to keep the
wire from moving and off the roof, secured to the racking, thus not
compromising the insulation. 

 

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