[RE-wrenches] AFCI disturbances. wire nuts

Wed Jun 25 11:40:58 PDT 2014

Brian,

You mean something like this? http://www.mcmaster.com/#butt-splices/=skc88h

-N

On Wed, Jun 25, 2014 at 2:38 PM, Brian Mehalic <brian at solarenergy.org>
wrote:

> I agree, the pre insulated splices are okay for if you need an extension
> in a box, that stays dry, and the wire isn't pushed up against something.
> Otherwise apply separate heat shrink after the splice. Just don't forget to
> slip it on the wire before splicing!
>
> I kind of like the idea of a properly torqued set screw splice with
> insulated heatshrink. There's got to be a direct bury kit available.
>
> Brian
>
> On Jun 25, 2014, at 2:01 PM, Ray Walters <ray at solarray.com> wrote:
>
> I've had butt splices fail, due to a ratchet release type crimper that
> didn't pinch the wires tight enough.
> I now use a good old Klein crimper that puts a big indent on one side.
> The problem with this however, is that it damages the built in insulation.
> My favorite butt splice is uninsulated, and then slide adhesive shrink wrap
> up tubing up over the connection after.  We use these on submersible pumps
> that are 100 ft under water with no issues.
>
> R.Ray Walters
> CTO, Solarray, Inc
> Nabcep Certified PV Installer,
> Licensed Master Electrician
> Solar Design Engineer303 505-8760
>
> On 6/25/2014 11:43 AM, Nathan Charles wrote:
>
> 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
>> <http://solutions.3m.com/wps/portal/3M/en_US/EMDCI/Home/Products/Catalog/%7E?%0AN=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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-- 
Nathan Charles
Engineer
NABCEP Certified PV Installation Professional #042013-20
Paradise Energy Solutions
(717) 283-2021 direct
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