[RE-wrenches] Buchanan Crimp in 1000v Applications and the NEC

[Blake Gleason]

We use MC4 plugs to splice #10 wire inside j-boxes.  You need a slightly
larger (or longer) box, but you get a great, watertight connection, simple
test points, easy string isolation, etc.  And they are UL Listed for 1000
(or 1500) V.

I looked for years for UL listed (not just UL recognized) splice terminals,
but all of the reasonably-priced DIN rail terminal block options seem to be
made to go inside factory-assembled machines, and are UL recognized only.

Ilsco makes UL Listed PDBs, but they are larger, MUCH more expensive, and
really not practical for splicing lots of 1:1 #10 wires.

(And yes, many inspectors around here are willing to die on the
Listed-vs-Recognized hill...)

Blake

On Tue, Nov 11, 2025 at 1:16 PM William Miller via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> https://www.grainger.com/product/MERSEN-Power-Distribution-Block-1-25CC04
>
>
> I prefer terminals fastened in place and accessible tor testing. One
> option is above.
>
> Or:
>
>
> https://www.rexelusa.com/p/2986/allen-bradley/terminal-block-150a-1000v-ac-dc-gray-35mm-feed-through/662073058373/1492-j35
>
>
> https://www.phoenixcontact.com/en-us/products/multi-level-terminal-block-pttb-4-l-1000v-3062744
>
>
> Or McMaster-Carr:
>
> 7641K52
> <https://www.mcmaster.com/product/7641K52>
>
>
> William Miller
> Miller Solar.com
> 805-438-5600
> www.millersolar.com
>
>
> On Tue, Nov 11, 2025 at 10:15 AM Sam Haraldson via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> Wrenches,
>>
>> On the attached product spec sheet for Ideal Copper Crimps (aka Buchanan
>> crimps) you'll see that max voltage for the crimp is rated at 600V but an
>> asterisk indicates up to 1000V when "in fixtures and signs".  In our
>> application this is a 1000v system and we are joining pairs of #10 PV
>> wires.  The junctions are made in a rail-mounted, plastic j-box.  We could
>> not find the definition of "fixture" as it might pertain to this situation
>> in the NEC and as such are interested to learn more about using Buchanan
>> crimps for 1000V applications.
>>
>> [image: image.png]
>>
>> Cheers,
>> Sam
>>
>> [image: OnSite Energy] <https://onsiteenergyinc.com/>
>>
>> Sam Haraldson
>> Operations Specialist
>> (406) 551-6135
>> 1515 N. Rouse Ave Bozeman, MT 59715
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-- 

Blake Gleason, PE | Employee Owner
Director of Innovation and Technical Excellence
O: 510-845-2997 x128
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