The exception under 690.8(B)(1) definitely applies. All of Midnite'
breakers and boxes are rated for 100% continuous operation. I believe,
this does not apply to their touch safe fuse assemblies, however. Also
FYI, you should be able to use the 90 deg C rating for complying with
110.14 (C) at least for the terminals in Midnite's combiner. (This is
according to my conversations with Midnite)
Also, it seems that you might be exceeding the max fuse rating of the
modules. You might want to check that. Why not have each series
string on its own 15 amp breaker?
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 11/9/2016 6:57 PM, Jerry Shafer wrote:
Wrenches
We are getting some questions from PRMD some questions relating to
690.8 here is what we have
3 modules, 260 watts at 9 amps ISC each module is a single string which
goes into a MNPV6 disco/combiner/disconnect
combined to a 30 amp breaker, it is being replaced with a 40 amp per
690.8(A) 1
leaves there and goes to a 32 amp disconnect in our device.
here is where it gets interesting
690.8 (A) requires the 40 amp breaker but reading down to 690.8 (B) 1 we
need to up-size to 50 amps (no 45 amp is non available)
We also have added the 63 amp GFI in the disco
we have also moved up from # 10 wire to # 8 wire as a result
All this seams over kill for three modules, there are 2 exceptions but
PRMD do
not feel they are relative.
Is the Midnite solar disco considered an assembly with the bus bars
inside if we install the breakers
Any ideas would be helpful
Jerry
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