SB304- SB50 limits [RE-wrenches]

[Phil Undercuffler]

----- Original Message -----
From: <sunwise at cheqnet.net>

<snip> I've used 3/4 inch liquid tight and bushings on
> the RV end on the last couple SB50's I installed.

3/4" liquid tight?  How in God's green earth do you fit adequate wires into
3/4"?  Much less if you use 90s, which seem to be even harder to cram wires
through!

Figure that's two wires in, two wires out, plus ground, plus temp comp, plus
shunt sense.  When I do the math, figuring 40% fill area for more than 2
wires and 18 gauge for the sense wires, that works out to #10 wire max!
Unless you are only using a 3048 AND using it to downcut 48 volt arrays to a
24 volt battery bank that really seems to be choking the performance you
paid for.

I usually  use minimum #6 to utilize the 50 amp output capacity (with a 60
amp breaker).  That gets hard to  cram through even a 1" offset.  My wish
list would be 1 1/4" KOs, not 3/4".  I've only found the 1/2" handy if I'm
routing the temp sense directly to the batteries and not through the main DC
feed conduit.

FYI, in many instances I use a 1" offset out the right hand side of a DC
Disconnect into a QO 2-4 70 box and another 1" offset going up into the SB,
and use a two pole breaker to handle both sides of the controller.  Frees up
a little space in the DC disconnect for ease of access or DC loads and the
trio nestles up nicely.  In addition an oversized array input conduit and
wire can easily be terminated at the QO.  The box and breaker is about the
same cost as two Heinemanns.  John Wiles questions using QO breakers on 24v
array inputs, but I have no reservations.

Enjoy the Sun!

Phil Undercuffler
Positive Energy

"The most beautiful experience we can have is the mysterious....
the fundamental emotion which stands at the cradle of true art
and true science"  --Albert Einstein

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