Gray Flex [RE-wrenches]

[Bob-O Schultze, Electron Connection]

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>Joel and others,
>
>The point is not that air conditioners don't get hot and wet, they just
>don't get nearly as hot as the back side of a PV module.

I'm sorry Bill, but this is absolutely untrue. During summer module 
testing at Home Power a few years back we measured peak module 
temperatures (in contact with the back of the module) between 48 and 
56°C at or near solar noon. The FNC does not contact the back of the 
PV in any way except where it goes into the J-box and that typically 
has an inch or so of plastic J-box material between it and the module 
itself which acts as at least a few degrees of thermal insulation.

> For roof mounted
>arrays in warm climates (Los Angeles), it is best to use 75C as the hottest
>ambient temperature (on the back of the module). This means that the conduit
>must be rated for at least 80C (wet since it is outdoors). The conductors we
>use to connect to the module must be at least 90C rated to allow current
>flow (a 75C wire at 75C has zero ampacity by definition). Non-Metallic
>Flexible Conduit is normally 60C wet rated but can be purchased in 80C,
>which is fine to use.
>
>If you are mounting the modules in an open rack like most of our off-grid,
>ground-mount and pole mount systems, the hottest temperature never go above
>about 65C, so 75C wire is okay, but the 0.33 multiplier must be applied to
>the ampacity calculation (e.g. 10 ga. wire has a 16 amp ampacity at these
>temps).

Bill, you have not actually measured this, have you?
Also, 105° THHN wire is readily available at any electrical 
wholesaler. It costs little or no more and is my wire of choice for 
array wiring.
Bob-O

Bob-O Schultze, Electron Connection
PO Box 203, Hornbrook, CA 96044
800.945.7587 or 530.475.3402
fax 530-475-3401
www.electronconnection.com

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