[RE-wrenches] Ferrules for large fine-stranded wire.

Sat Jan 24 07:15:14 PST 2026

Hi,
Before investing in the Greaves adapters, I previously bought both normal
and narrow 4/0 ferrules. Neither fit the 4/0 max terminal block of the
Fortress Envy.

On Sat, Jan 24, 2026 at 8:36 AM Jay via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> I got curious about ferrules.
>
> Turns out they come in different physical  sizes for the same wire size.
>
> I’ve found .63” and .69” OD for 4/0 wire.
>
> With .69 being more normal and. .64 called small diameter
>
> Try measuring what you’ve got. Or the actual diameter in the inverter.
>
> I’m mean no excuse for the rep being clueless
>
> Jay
>
>
>
> On Jan 23, 2026, at 10:46 AM, Kirk Herander via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> 
> William, All,
>
> I was at a workshop on the (sort of) new Fortress battery product the
> other day. I brought up this very
> issue of the terminal lugs of the Envy not accepting a 4/0 ferrule, even
> though 4/0 cable with ferrules are recommended in the manual. The
> instructor had no comment, except to imply that maybe one should use 3/0
> max. Huh?
>
> Anyway these Greaves pin adapters are by far the best I've found for
> working with the 4/0 terminal block.
> The pin diameter matches 4/0 cable and thus fits great. Preferable IMO to
> a reduced 4/0 barrel to 2/0 pin of AL or AL-clad others. And the barrel has
> a generous flange which makes it quite easy to insert high-strand flex
> cable.
> #PT 222FX40. But @ $50 ea, not cheap.
>
> <image.png>
>
>
> On Wed, Sep 3, 2025 at 7:10 PM William Miller via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> Friends:
>>
>>
>>
>> My understanding is if the lug has a set-screw that contacts the strands,
>> fine strands can wind around the set screw, get into the threads and not
>> tighten adequately.  If you are crimping fine strands inside of some type
>> of barrel your connection should be OK.
>>
>>
>>
>> I had been using Outback until they imploded and all of the battery
>> connections were via studs or bolts that required crimped-on rings.  Now I
>> am back to set screw lugs and fine stranding became an issue again.
>>
>>
>>
>> I did try another experiment: I took a 4/0 ferrule that would not fit
>> into the Envy lugs and snipped a section out of it.  I curled it into a
>> slightly smaller diameter and it fit into the lug.  I suppose one could cut
>> the ferrule in half longitudinally and insert a portion of the ferrule
>> between the set screw and the strands.
>>
>>
>>
>> I am pleased with the copper sheeting wrapped around the fine strands.
>> That will be my SOP.
>>
>>
>>
>> William
>>
>>
>>
>> Miller Solar
>>
>> 17395 Oak Road, Atascadero, CA 93422
>>
>> 805-438-5600
>>
>> www.millersolar.com
>>
>> CA Lic. 773985
>>
>>
>>
>>
>>
>> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
>> Behalf Of *Ray Walters via RE-wrenches
>> *Sent:* Wednesday, September 3, 2025 1:40 PM
>> *To:* re-wrenches at lists.re-wrenches.org
>> *Cc:* Ray Walters
>> *Subject:* Re: [RE-wrenches] Ferrules for large fine-stranded wire.
>>
>>
>>
>> I've got to ask: Are none of the lugs on these Chinese inverters approved
>> for fine strand cable?  I just have not had a problem with that, but I've
>> mostly used Magnum, Midnite, and Outback equipment over the years.   What
>> were the lugs on the old Trace DC 250 boxes?  Were they fine strand rated?
>> They sure were tough to get 4/0 into, as William mentioned.
>>
>> Ray
>> Remote Solar
>>
>> On 9/3/2025 12:57 PM, Kent via RE-wrenches wrote:
>>
>> William,
>>
>> If the only reason the ferrule wouldn't fit after using the hex crimper
>> was the ridge left where the dies meet, you could rotate the cable 120
>> degrees and crimp the ferrule again.
>>
>> I doubt that the indenter crimper will do a decent job with large
>> ferrules.
>>
>> I do like your thin piece of copper solution. Not UL approved but I dare
>> say wrench approved.
>>
>> Kent Osterberg
>> Blue Mountain Solar
>>
>>
>>
>> On 9/2/2025 8:55 PM, William Miller via RE-wrenches wrote:
>>
>> Friends:
>>
>>
>>
>> Thank you for all of your input on this question.  I feel it only right I
>> report back how this turned out
>>
>>
>>
>> I tried a crimper like this:
>>
>>
>>
>>
>>
>>
>>
>> It left a jagged ridge on both sides of the ferrule where the dies met.
>>
>>
>>
>> The crimper below was suggested but I have not tried it:
>>
>>
>>
>> This was suggested but I have not tried it either:
>>
>>
>>
>>
>>
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>
> --
>
>
> *Kirk Herander / **kirkh at vermont.solar <kirkh at vermont.solar>*
>
> *Owner|Principal, VT Solar, LLC*
>
> *Celebrating our 35th Anniversary 1991-2026!!*
>
> dba Vermont Solar Engineering
>
> 802.559.1225
> _______________________________________________
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-- 

*Kirk Herander / **kirkh at vermont.solar <kirkh at vermont.solar>*

*Owner|Principal, VT Solar, LLC*

*Celebrating our 35th Anniversary 1991-2026!!*

dba Vermont Solar Engineering

802.559.1225
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