[RE-wrenches] AFCI disturbances.

[William Miller]

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 ---
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