Single complaint about the classic-input/output terminals

[boB]

Tinman,

Fine stranded wire can be difficult to manage, as it is a bit larger diameter than THHN,   and the conductors have very little rigidity compared to THHN.  This can make it difficult to use.

Fine stranded #4 wire is electrically 4 AWG but is physically more like #3 or #3 1/2 gauge wire.  That's why it can break off
fine strands.  The conductive part of the TB itself is UL rated for #14 to #4 wire.

#4 THHN wire fits just fine in the TB.  It's a bit tight, but I could insert it just fine here.  Also our pre-wired E-panel department does this every day.

As for the screw getting in the way, yes it may give you a problem with fine stranded #4 wire but the screw does not enter into the inside #4 circle of the conductive TB hole itself.  That part is not going to get any larger.

BUT, the terminal block plastic part can be slightly modified to take care of the problem where the #4 wire hits the outside front of the conductive part of the terminal block and this is what is being fixed right now.

There must be a PV disconnect between the combiner and controller.  That is where one can use the proper #4 wire to go into the TB for the short run to the controller.   There will usually also be a negative bus TB for the negative wire as well.

But still, we are working on the TB for the wire to be more easily inserted without hitting the metal conductive TB piece. That should improve things a lot.
boB

[laszlo]

Ryan,

This block looks good. Make it flush with centerline of bottom knockout.   I addressed TB issue early on - last June or July. I am glad Midnite is looking into this.   

TinMan
The box lug in the terminal block is designed for #14 - #4. The issue I see is the blue shroud hides it and makes it VERY hard to access. I have some ideas on making this better. Here is a picture of my crude prototype.

On the temperature jack that has been fixed since around serial#2400 the Ethernet is another issue they just do not seem to make jacks that are backwards? We are looking at removing some circuit board on the next revision to make it easier to get at? We never assumed people would unplug these things that often.

Ryan

[epsgunner]

Ryan,

With all due respect I have had problems recently trying to install one where the client had just damage an old mx and it was being fed with 4awg building wire(19 strand) and I had to cut off about 3 strand to get it inside the termnial box.

Is there any real downside to trimming?? I have multi-strand 75/105C 4 AWG wire with 7 bundles of TC Copper wire in it... can I safely trim off to get it to fit??  I know DC flows around the wire and not thru it..

I have 6 AWG multi-strand 75/105C wire here I am using for testing but it would be nice if I can use the 4 AWG that I bought specifically for this controller..

The run down to my battery bus board will only be about 30"..

[niel]

"I know DC flows around the wire and not thru it.."

where did you get that idea from as that is not true? higher frequency ac tends to migrate to the outside areas of wires and gets more pronounced the higher up in frequency you go. the only advantage the many small strands that make up a cable being used for dc is that it is flexible and less prone to breaking. it has nothing to do with where on or in the wire the current passes as it flows in the entire cross-section of it.

[epsgunner]

I thought I read it..

So can I trim some strands off to get it in??

I really would prefer that 4 AWG to be used and my 100 amp breaker vs. the 6 AWG and 100 amp breaker (which wouldn't kick in till after the fire.. LoL)

[Vic]

Hi Al,

As niel mentioned,   the Skin Effect describes the nature of current flow of high frequency AC.  The skin depth is less,  the higher the frequency.  But DC currents use the entire cross-sectional area of a conductor.

As an aside,  in free air,  #6 AWG THHN building wire has an Ampacity of 105 Amps for ambient temps up to 30 degrees C,  if that would help -- depends upon how exposed the wiring to the CC would be in your installation.

As noted by boB earlier in this thread,  the output breaker is a great place to make the transition from the #4 to#6  AWG wire.  If the length of #6 is short,  less than about 12 inches,  #6 should  be fine.

Have fun,   Vic

[boB]

As for energy flowing around the conductor, he may be thinking of things relating to the "Poynting Vector"

http://en.wikipedia.org/wiki/Poynting_Vector

boB

[epsgunner]

The 4 AWG issue has me miffed and I now have 4 1/2' of 4 AWG wire to use for battery leads I guess..

I changed things up today.. I got the Classic 150 mounted on the side of my combiner box using the 1" pipe nipple trick.. and mounted both to 3/4" plywood for ease of moving it..

Before mounting to wood..



I changed the wire to 6 AWG to go down to my bus board for the battery bank.. I left about 3 1/2 feet of wire length but will be shortening that up upon install in the TX location.. The bus board will end up like only 12" below the classic..

I figure I won't be pushing more than 60 amps to the battery with my setup at this time..

If I add more panels I'll be doubling upto a 24v battery bank so the amps will get cut in 1/2 again anyway..



The battery bus board doesn't have the Plexi cover on it in this shot.. but rest assured I put something over those bars.. and no worries the 3/0 inverter wire will be shorted from that 42" you see to as short as possible when I get setup as well.