Missing Junction boxes on modules[RE-wrenches]

John Berdner jberdner at sma-america.com
Tue Aug 21 10:39:56 PDT 2007


John/Wrenches:
 
I discussed this language at length with John WIles, Rob WIlls, and
Ward Bower as part of the 2005 code cycle.
Unfortunately, the Code Panel misinterpreted what we were saying and
this is the reason we got the requirement for conduit or double jacketed
multi-conductor cable for ungrounded systems.
In 2008 we are trying to get the Code back to the real issue and it
looks like they got right it this time, i.e. the proposal has been
accepted in principle.
 
The issues pointed out here on the list are exactly the reason for the
new requirement for conductors to be in conduit in readily accessible
areas.
I have unpleasent visions of some 5 year old swinging on a single
conductor cable with MC connectors that is hanging down off the back of
a pole mounted array.
So far I not found one installer who feels that would be ok if it was
his or her child playing with the wire. 
Locking connectors or not, zip ties or not.
 
The term "readily accessible" is key here.
Roof mounted arrays are typically not readily accessible (as defined by
Code) so single conductors with MC connectors are ok.
The exception would be cases where there was an unlocked door for roof
access.
 
Also, the wiring on the back of an array could be made inaccessible
with the addition of an "L" shaped guard bolted to the back of the
modules on some short standoffs.  There is no reason to cover the entire
back of the module, only the wires.
The guard could go from the module frame down over the wiring and then
bend down towards the module back skin.
The standoffs give room for the wire to pass from module to module.
The wiring would no longer be readily accessible (a tool is needed to
access the wire) so it would not need to be in conduit.
It could even be made of expanded metal to avoid thermal issues.
 
Since by definition the back of the modules are in a readily accessible
are the installation should be pretty quick too.
Perhaps this is something the racking guys could offer if the modules
guys don't step up with J boxes or some type of guard.
 
Best Regards,
 
John Berdner
 
 
 
 
 
 
 

 
 

>>> john at raynes.com 8/18/2007 09:01:14 AM >>>

It's my understanding that the 2008 NEC will require all conductors to

be in conduit if the array is readily accessible (i.e., ground mount 
and not fenced off or barricaded in some manner).

Hopefully this will give some impetus to manufacturers to make some 
more J-Box offerings available. More realistically, I think it will 
take a combination of stricter code/inspection requirements, and a 
solar panel market that is no longer supply-constrained. As long as 
panel manufacturers can sell everything as fast as they can make it, 
most of them figure why bother for now.

We're finding Kyocera KC130TM J-Box modules available at reasonable 
prices through a couple of sources this season, and are using them 
where it makes sense. We're also becoming increasingly curious about 
the Photowatts for this reason, and for the fact that they provide 
12/24 volt models, much better suited for our off-grid work. The 
problem with the Photowatts is that they're not readily available 
through normal distribution channels to my knowledge, which means 
entering into a purchase agreement with Photowatt directly with 
guaranteed volumes. Do any wrenches know more about the supply 
situation with Photowatt, or have experience with using them in 
systems? I think that some of their models are not UL listed but 
others are.


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