[RE-wrenches] Flexible stranded Connectors

[William Miller]

Ray:

Darn good question, especially since I will be doing the exact same thing, *tomorrow*.

I have never been clear on the real problem. Fine stranded cables overheat in the wrong lugs?  Is this true for mechanical or compression?

Aside from code compliance, what is the best common sense approach to Sunny Islands with fine stranded?  Annual retorquing?  Pin terminals?  Solder tinning the strands?????

I used to wrap thin copper sheeting around fine stranded just to corral the strands. Is this a possible solution?

Thanks Ray for bringing up a question I forgot to consider. 

William


Miller Solar

> On Apr 29, 2014, at 10:48 PM, Ray Walters <ray at solarray.com> wrote:
> 
> Hi All;
> 
> In order to avoid any of my work showing up in someone's slideshow of horrors, I'm trying to find the correct way to wire 3 Sunny Islands with Cobra X flex cable.
> While it doesn't actually mention it in the SMA manual, a call to SMA tech support confirmed my suspicions: the DC lugs in the inverter are NOT rated for flex or fine stranded cable.
> Both SMA and CED recommended I try Grainger's for crimp on adapters.  Grainger had no clue, and nothing came up in searches there.
> From a trade show, I have an ILSCO lug book, that shows a crimp on pigtail adapter.  It does not mention whether its flex rated though on the crimp side of the adapter, as the adapter is used primarily to land over sized cables into smaller lugs.  (2/0 to #1, for instance)
> The best I've found so far, is NSI, which makes sleeves, that are installed around the wire, right in the connection:
> http://www.nsiindustries.com/products/electrical/connectors/compression-connectors/copper-compression/fsflex-cable-sleeve.aspx
> I also found a Schneider white paper recommending sleeves with their lugs:
> http://static.schneider-electric.us/docs/Circuit%20Protection/0515DB0301.pdf
> 
> So who has used these sleeves, and where do I get them?
> The sleeves seem like a decent compromise, whilst the ILSCO pigtail adapters are coming in at $40/ ea...... (ouch)
> 
> On the internet, I'm seeing several examples of X flex used directly (no adapters) with the Sunny Islands, so are folks just blowing off articles 690.31(F) and 110.14, that specify the connector be rated for flex cable?
> And finally, couldn't SMA use a lug that was flex rated?
> For example, Marathon makes Class K rated mechanical Lugs: http://www.marathonsp.com/NewRatings.html
> I'd use THHN, but I really don't feel good about wiring the Heineman breakers with that stiff a wire.  I've cracked breaker cases before......that's why the X flex is industry standard for off grid DC.
> 
> Thanks for your help,
> 
> -- 
> R.Ray Walters
> CTO, Solarray, Inc
> Nabcep Certified PV Installer,
> Licensed Master Electrician
> Solar Design Engineer
> 303 505-8760
> 
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