[RE-wrenches] AFCI disturbances. wire nuts

[Nathan Charles]

Hi All,

Has anybody had success with these butt splices with the adhesive shrink
tubing?  http://www.mcmaster.com/#butt-splices/=skb9qs

Best,



On Wed, Jun 25, 2014 at 1:12 PM, August Goers <august at luminalt.com> wrote:

> Hi All -
>
> We have been using outdoor Ideal brand wire nuts (the blue ones packed
> with waterproof gel/grease) for all of our residential DC side splices
> (typically #10 wire) for 10 years now and have never had a single problem.
> If the installers properly strip the conductors and follow the
> instructions I feel that these wire nuts make very robust connections. We
> always do a good pull test after twisting the wire nut on. I would never
> recommend standard wire nuts without the grease and have seen these fail
> numerous times during inspections of systems installed by others.
> Insulated terminal blocks also work well but don't have that nice
> waterproof grease in them to help avoid moisture issues. You can wrap them
> with a good splicing tape to help keep moisture out but the cost for these
> connections is significantly higher than wire nuts:
>
> http://solutions.3m.com/wps/portal/3M/en_US/EMDCI/Home/Products/Catalog/~?
> N=5433135&rt=c3
>
> Normally I error on the robust conservative side of the installation
> spectrum but in this case it sounds like I may not.
>
> Just my $0.02
>
> Best, August
>
>
> -----Original Message-----
> From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On
> Behalf Of William Miller
> Sent: Wednesday, June 25, 2014 8:40 AM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] AFCI disturbances.
>
> Richard:
>
> Possibly. I think I prefer din mount connector blocks. However, if a wire
> nut can arc internally a connector block might also. I am still wondering
> about this concept.
>
> William
>
> Miller Solar
>
> > On Jun 25, 2014, at 6:09 AM, Richard.L.Ratico at valley.net (Richard L
> Ratico) wrote:
> >
> > William,
> > Would UL listed crimp sleeves be an acceptable substitute where you
> > would otherwise use wirenuts?
> >
> > Dick Ratico
> > Solarwind Electric
> >
> >
> > --- You wrote:
> > Bob-O:
> >
> >
> >
> > When you say verboten, what does that mean?  Not kosher?  Frowned upon?
> > Disallowed by law???
> >
> >
> >
> > I am quite curious about this subject.  Here is what I have learned so
> far:
> >
> >
> >
> > This is a unique case where we are replacing 3 dead SMA U series
> > inverters with 2 US series inverters.  The U series seem to all be
> > dying at about 12 to 14 years of age.  We have about a dozen of these
> > to swap on our calendar and expect more.  It may be that to do this
> > right requires that we pull new wire from the arrays.  This makes the
> job a lot more expensive.
> >
> >
> >
> > We have never used a wire nut on a PV lead until this project.  It's
> > not that we disapprove of wire nuts in general, it is because we know
> > that if we were to use them regularly we would eventually have failures
> and call backs.
> > We allow only one splice in a PV lead: between the cable provided by
> > the manufacturer of the module and a bulkhead mounted MC4 connector
> > direct to THWN in conduit
> > (http://millersolar.com/MillerSolar/practices/PV_wiring/PV_Cable_wirin
> > g/_PV_
> > Cable_Wiring.html).
> >
> >
> >
> > We checked the manufacturer's listing and the wire nuts are rated for
> > 600 volts.  We do use wire nuts on AC circuits, such as switch and
> > receptacle circuits in a power room.
> >
> >
> >
> > A tech at SMA told me that wire nuts "arc internally to the spring"
> > causing the AFCI faults.  I am not aware of any process of "internal
> > arcing."  To me, arcing means, as per the dictionary definition: "a
> > luminous bridge formed in a gap between two electrodes."  The same
> > tech told me to solder the leads and apply shrink tubing.  I don't
> > believe this is an approved method.  By the way, we have spliced leads
> > on both US series inverters and only one is exhibiting AFCI
> disturbances.
> >
> >
> >
> > I do favor mounted terminal blocks, either screw or tubular type. I
> > need to check if the Amp model we stock are 600 volt rated.
> >
> >
> >
> > I was told by another representative from SMA that on a ground-mount
> > system it is legal to disable the AFCI protection.
> >
> >
> >
> > I will be troubleshooting this job tomorrow and I will let you all
> > know what I learn.
> >
> >
> >
> > William Miller
> > --- end of quote ---
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-- 
Nathan Charles
Engineer
NABCEP Certified PV Installation Professional #042013-20
Paradise Energy Solutions
(717) 283-2021 direct
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