Module Conductor Temperatures [RE-wrenches]

[Jason Fisher, Aurora Energy]

Friends,

I just installed 3kW of Astropower 110s for a grid-tied customer and was
pleased to notice that Astropower now has a minimum conductor temperature of
75 degrees noted on these modules.  I checked an older AP-75 and it was 90
but a new AP-120 was also 75.  The series fuse was also stated at 15 Amps on
the 110s and 120s.  This means that legally, one could hook up these modules
with regular THWN (not type II) and most TC cable.  UF would still not be
acceptable because of its 60 degree rating and I'm sure that this change
would not convince Mr. Wiles that "Carflex" (NM Flexible Liquidtight) would
be an acceptable conduit, but it seems like a positive step in the right
direction.  I have always wondered if the 90 degree rating was not the
result of a misunderstanding by the manufacturers and the NEC.  Since THWN
has a 90 degree rating when dry and only drops to 75 in wet locations.  PV
panels can get hot when dry, but usually are not so when wet.  I have also
wondered at what point, technically, can we make a transition to lower temp
wire?  Once you hit a 75 degree rated fuseblock or other terminal, or once
we enter a "dry location"?  I've never asked an inspector though, afraid of
starting an over analysis of a system!

This said, I'm not sure whether I'll start using THWN right away on these
modules.  How about you all out there.  Have you found heat damaged
insulation on module wires on older systems?  I know that UF cable was (and
is?) pretty common as well.  Do you all consider the use of USE-II, RHW-II,
and THWN-II only when getting inspected or is there validity in this
requirement?

thanks
----

Jason Fisher
Aurora Energy
86 Conduit St.
Annapolis, MD 21401
USA

Voice/ Fax: 410-268-3088
email: aurora at toad.net


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