M-C branch plugs: Legal? Safe? [RE-wrenches]

[Ray Walters]

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First, you can't use those connectors to create more than 2 parallel  
strings, so I'm not sure how you would parallel 3 strings. (unless  
you doubled them up?)
2nd, we never exceed the fuse string series rating. We use Solar  
World 165s: the series fuse rating is 15 amps, and we have 2 modules  
with a Asc of 5.5, then we have 11 A of current x 1.25 = 13.75 A,  
which is under the 15 A breaker we will use to protect this  
paralleled sub array. We are using a 100% duty rated breaker, so we  
don't need to use the full 1.56 multiplier.
We have actually seen damage many times from over paralleled arrays.  
The connectors themselves (inside the module j-boxes) have melted  
from the heat from a slightly loose connection.
30 amps all day every day x some slight resistance can equal enough  
heat to do damage.
I wouldn't exceed the fuse rating of the module, End of Story. I can  
create some nightmares using all UL listed equipment. Just because it  
goes together doesn't make it right.

Ray Walters


On Feb 4, 2008, at 8:50 AM, Mick Abraham wrote:

>
> Hi, Wrenchers~
>
> The Multi-Contact "branch connectors" connect two PV strings in  
> parallel
> by just plugging them together. MC part numbers for these "branch  
> plugs"
> would include PV-AZS3 & PV-AZB3.
>
> These connectors have a UL recognition mark, but they seem non-code
> because there's no individual fusing for each string of modules.
>
> Are code issues raised by this product? I'm working on something where
> there are no codes, so my other question is: are safety issues raised?
>
> Specifically, if one plug-parallels three Kyocera 135's (with, say,  
> one
> 30 amp breaker to protect the trio from the 12v battery side), is that
> hazardous? 30 amps exceeds the series fuse rating recommended for the
> KC-135 which again seems non-code. On the other hand, if one uses 10
> gauge plug leads (which are likely fine with 30 amp protection),  
> perhaps
> the worries are small.
>
> Multi-Contact rates the branch plugs for 30 amps when 10 gauge wire is
> used. If they're non-code, however, who uses them, and how?
>
> Thanks all around,
>
> Mick Abraham, Proprietor
> www.abrahamsolar.com
>
>
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R. Walters
Solarray.com
NABCEP # 04170442	




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