[RE-wrenches] AFCI disturbances.
William Miller
william at millersolar.com
Wed Jun 25 08:40:03 PDT 2014
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_wiring/_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 ---
> _______________________________________________
> List sponsored by Redwood Alliance
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> www.members.re-wrenches.org
>
More information about the RE-wrenches
mailing list