[RE-wrenches] Polaris gone bad?

Mon Apr 10 12:48:37 PDT 2017

Good discussion here. I will not rule out loose connections entirely but I will say that our installers know that can be an issue and really tighten their connections. I like William's suggestion of fabricating an MC-type connector at the PV Wire to THWN transition. At least I presume that's what he's suggesting. Indeed we've moved away from the screw-type Polaris and are not interested in the old-fashioned wire nut. We're 100% Sunpower and they recommend the Buchannon's so that's what we're installing today. However, I'm going to investigate the Miller method. William has never led me astray!

Eric Stikes
SunHarvest

--------- Original Message --------- Subject: Re: [RE-wrenches] Polaris gone bad?
From: "William Miller" <william at millersolar.com>
Date: 4/8/17 2:48 pm
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>

Wrenches:

I am wondering why the proliferation of splices in PV leads?  We all know splices are a weak link. 

We allow only one connection between a module and the feeder destination-- be it a combiner, inverter or optimizer-- and it is an MC connector, one side of which is factory-made and provided by the module manufacturer. 

If one plans and pulls PV circuits with forethought, splices should not be necessary.   

If anyone wants to know more about how this can be accomplished, look at our web site or contact me off list. 

William

On Apr 8, 2017, at 10:05 AM, Glenn Burt <glenn.burt at glbcc.com> wrote:

   It is also worth noting that many of the SMA installation manuals specifically say do not use wire nuts on DC wiring. 
Of course choosing to ignore the manufacturers installation instructions would be a NEC violation.

From: Drake
Sent: ‎4/‎8/‎2017 12:10
To: RE-wrenches
Subject: Re: [RE-wrenches] Polaris gone bad?

 At 01:35 PM 4/6/2017, you wrote:
 Recently we interfaced with another solar install firm that has gone back to wire nuts due to this same problem. 
 Wire nuts have the advantage of holding the wires tight with a spring. The spring follows the cold flow of the copper over the years. A screw type connection does not. 

 When I service an old breaker box, usually the wires are loose under the screw connections, especially on the neutral and grounding bars. Often they are very loose, and I bet that the screws were tight after the initial installation of the equipment. 

 On old industrial control equipment, I've learned the hard way to tighten all screws before doing anything in the box, as wires are prone to fall out of the loose screw connections. Again, these connections have the weakness of being held by terminal screws, with no spring to follow the cold flow of the metal. 

 With wire nuts, it can be a bit tricky to know if you have a good connection, as the connection is hidden under the plastic cap. It is good to pull hard on each wire separately to be sure it is securely under the spring. It is crucial never to mix copper and aluminum under a wire nut unless it is one specifically designed for the purpose. Unless specifically listed, all out door wire nuts should be in a weather proof box, and preferably taped. 

 Drake Chamberlin
 Athens Electric LLC
 OH License 44810
 CO License 3773
 NABCEP Certified Solar PV 
 740-448-7328
 http://athens-electric.com/ 

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