Runnin' Down a Mystery. Does the Classic Accept 4AWG Wire?

[harryn]

Just to close the loop on this I finally picked up some #4 THHN. Sure enough it slipped right into the terminals on the controller.

The vendor who sold me the fine stranded wire (Windy Nation) did not think the #4 THHN would fit, thinking that if his fine strand #4 wouldn't fit neither would the THHN. But in fact his #6 didn't really fit without shedding a few strands. The simple fact is that particular fine stranded wire is significantly bigger around. Good wire, just fat.

I feel a LOT better having the THHN wire attached to the controller now. Looks right. Feels right. End of story.

jim

Jim said in the discussion above what size wire fit in the terminal .

Larry

Thanks - yes I saw that AFTER the project attempt on Saturday.

Unfortunately, it doesn't really help with the actual goal of using ABYC wire that we already use for other applications, but looking into work arounds.  Thanks for the help.

[boB]

4 gauge wire has a diameter of 0.204 inches by my wire calculator.

I suppose that stranded wire depends on how compressed it is but there will be
air in between those strands.  The more strands, the more air of course.

boB

[australsolarier]

concerning boot lace ferrules:
a 4awg ferrule will not work, not even a 5awg (16mm2)  the reason is, the crimper will shape that round end of the boot lace ferrule into a rectangle.

i have 4 midnite classics. here the largest wire that gets into those small terminals are 16mm2. but i want thicker wire. i want the connection to be 35mm2 (2awg). so i made a crimp connection between a 16mm2 and 35mm2   coarse stranded wire (both 7 strands). i used normal copper pipe, in this case 9.5mm diameter, which is 3/8 in imperial and crimped with the hydraulic crimper. the 16mm2 end needs some off cut wires inserted to fill the smaller size diameter.
the 16mm2 stub end has to be about 6 inches long. the reason for this lenght is inside the midnite the wire has to be bent. either a 90degree angle to the sides. or an S-bend when directly downwards.
i understand the historical reason for the small diameter terminals in the midnite. however whilst wiring the midnite to the fusebox i spent 90% of the time at the small terminal end. and about 3 minutes crimping the other end for  and connecting to the dc fuse.

i have also tried cutting off half the strands of a 35mm2 wire. the above method though time consuming is more elegant and much safer.

what remains to be hoped is, that when midnite brings out that new mnb17 inverter, that they will take this into consideration. however whilst watching one of the videos there is that same small hole terminal block inside. maybe it is just for prototyping purposes. but i wouldn't bank more than 17 dollars on it.

[ZoNiE]

Sorry to dredge this up. I'm having a hard time with this, as MTW wire, which is fine stranded, is ideal for such a connection from the Classic to the battery in a mobile application - such as my motorhome and having to make a pigtail with THHN wire to MTW wire seems like a band aid.

Short of using a cable reducer, which is not ideal, what I am reading here is that the best course of action for me is to run rather stiff THHN wire with thick strands to a terminal block and then transition to the MTW? A ferrule, which I use plenty of on other things, only exacerbates the problem for me. I'm gonna have to add an Edison block to this installation.

Perhaps future revs of the classic could use a larger terminal block... Don't get me wrong, the Classics are great, but I think there needs to be more attention paid to using a larger terminal block and more space between contacts.

Extra connections are not ideal in any system, land or mobile...

[ClassicCrazy]

There is a lot of discussion on this on the forums - go to first forum menu page and do a search for 4 gauge and you will find them.  CDN-VT  did a mod where he was able to put ring terminals on the wires and made studs to fit in the Classic connector block - that is also documented on one of his posts.

Larry

[ZoNiE]

Yeah, seen some references to that. Site has a clunky search. Perhaps this should be a sitcky.

[australsolarier]

yes i agree the search function is totally useless

[boB]

Doesn't your positive battery wire have a circuit breaker or fuse holder close by to connect to ?  It is a convenient wire transition point.

The PV input is lower current than battery positive and doesn't need to be quite as big and the negative wire.  The Common PV/battery negative wire carries the difference between hot in and hot out so it doesn't have to be as large as battery positive either.

If you are using a separate negative for PV and battery, then the battery negative will carry the same current as battery positive.  But I think that 6 AWG is large enough for up to 100 amps.

Not sure what the deal is with search ?  That's part of the forum package.

boB

[australsolarier]

the deal with the search function is, that it does not bring up what you are looking for even though you know it is somewhere there. and, when doing  slightly different word combinations you have to start from zero again. this might just be for me.
and with the wire thickness, some of us like to use thicker than "recommended" wire. then there is the american standard and the rest of the world standard of wire thickness. you then have to go smaller than what the "american recommendation" is.

besides those screw terminals are not really world's best technology.  you look inside the breakers we have here:  there are two metal plates squeezing together to make a lot of contact. unlike just a screw digging into the wire bundle.
there are kind of ferrules  that have like a solid finger with a crimps at the other end. very difficult to get and expensive. (bought a packet, but they were too long then)

then you have the problem with the fine wire strands wire. it is thicker than the wire with say 13 cores or so. the fine wire strand wire is easy to bend, but not so the thicker core wire. you then have the problem with bending and running out of room. it is a really fiddly thing. unless you compromise with the smaller "recommended" wire.
so you wire up the midnight to the panels and fuse box and about 70% of the work is needed to just hooking up the 4 wires inside the midnite.

[Ron Swanson]

Onan generators for many years used (and may still use) a very simple, stupid system that just works.

Wrap the fine strands with a piece of brass or copper sheet a few thousandths thick.

Then crank down on the standard set screw terminal, no muss no fuss.

I carry this brass material in the truck just for this purpose.  A pair of scissors or a knife is all it needs.

However, it does not solve the problem of the screw terminal being too small for the larger bundle.  The whole terminal area of the Classic is too small as are the 1" knockouts.

[ClassicCrazy]

the deal with the search function is, that it does not bring up what you are looking for even though you know it is somewhere there. and, when doing  slightly different word combinations you have to start from zero again. this might just be for me.

I don't know why but the search for all topic only works from main forum page where all topics are listed. And yes it is a pain that after finding something you have to start all over on the search again. Maybe one of the Midnite forum admins can find the settings on the forum software to fix this ?

Larry

[ZoNiE]

I ended up running THHN to the main breaker, and MTW from that to the battery. For the Neg, I ran the THHN to an edison block and then MTW from that. It required an additional connection in a separate enclosure (an LB, in this case) but works. I just have two more terminals to inspect every so often...