Has anyone used 4 AWG cable on the terminals of the Classic (150 in my case). The manual states that the DC terminal connector will take up to #4 AWG THHN.
I happen to be using #4 AWG thin stranded. It does not even come close to fitting. I want to verify please that #4 THHN does indeed fit before ordering some.
Hi 5 - 2..,
YES, The Classic terminal block DOES accept #4 AWG THHN Stranded cable. The THHN stranding for that wire, is usually 19 strand. I HAVE used #4 THHN, it fits easily, but that is the largest THHN that it will accept.
The almost NO screw terminals are Rated for use with fine-stranded cable -- not only is the diameter of fine-strand cable too large for many busbars designed for a certain gauge cable, the fine strands can migrate out from under the screw (cold flow), and cause a once-good connection to become high-resistance. This can be dangerous, and possibly result in damage to the buss or terminal, it could possibly result in a fire.
If at all possible, use THHN cable of the appropriate gauge for the current flowing in the circuit.
Link to a THHN Wire Table:
http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheetOEM5
Vic
Mystery solved.
Great explanation. Puts me another few seconds down the learning curve.
So.... what is the argument for when to use the fine stranded? Is it only good for battery cables where you're crimping on a connector?
I bought 50' of fine stranded for a run between the combiner and the wiring panel (Magnum MMP). So what.... butt connectors and THHN at the termination points?
Hi 5 - 2..,
Yes, you are correct -- generally, fine-strand cable is intended to be used with appropriate Crimp lugs, and other crimp connections.
Being a bit too nit-picking, any of the crimp connectors used, should be designed for the stranding of the cable, and one should use the Crimper and crimp dies designed for the cable, as well.
Almost all of us DO use fine-strand cable for battery interconnects, inverter cables, and connections to large circuit breakers used for inverters, and other very large loads.
THHN is a compact cable, pulls easily through conduit, can be easily formed for good lead dress (neatness), and virtually all of the terminals and bussbar connections are designed to work well with building wire (THHN, THWN, THW, etc).
Some people use Ferrules on the end of fine-strand cable, but even these can create compatibility issues, at busbars, and other screw terminal connections.
We all have probably made crimp connections, that were not exactly by-the-book ... one needs to be careful, and watchful.
All just my opinions. Vic
Yeah. My finely tuned Jedi senses were setting off alarm bells when I tried to insert even 6AWG fine in the controller terminal block. Even at 6AWG it was a tight fit and a strand or two peeled off and wanted to kiss the adjacent terminal.
That is when I went back to the drawing board.
I've tried to make all my mistakes before spending $$. A few things have slipped by though and have had to make some minor design changes, and thus more $$.
Trying to find all the mistakes before flipping the switch. Baby steps.
It's about 3 minutes to Midnite right now. I should change my handle. ;>
I think VT has posted his solution for a mod to make it so he could put on ring terminals instead of using the screw terminals . It is on the forums here somewhere.
Larry
Switching out all of mine for #4 THHN. Lowe's sells it by the foot. I like "color coordination" but, Lowe's didn't have #4 in red (only black). However, they have #6 THHN in red and black (which will be used for the PV inputs from the MNDC250PLUS. Didn't check Home Depot for the #4 THHN in red. Both honor military with 10% discount.
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
Quote from: 5 Minutes 2 Midnite on May 06, 2017, 09:11:14 AM
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
Thanks for the follow up . Yeah the bigger strands makes the difference and compresses better in those terminals.
Larry
Glad you got it fitting !
boB
If you asked me this question yesterday, I would have said - "No it doesn't".
Of course I was trying to help a guy install one and we were using ABYC, 600 volt, tin plated stranded wire. The size of the 4 awg wire vs the size of the terminal hole are not even close.
Today I attempted to use quality cable inverter lugs as a possible alternative to inserting the wire itself, but even two of those have interference.
Changing wire type is complicated, because the other end is terminated with a heavy 4 awg Quality Cable magna lug that is put onto the MNEDC breaker thread, and my supplier is setup for that wire type.
Any suggestions for a crimp on termination that can be inserted into the classic terminal block?
Thanks
Harry
Hi Harry,
This has been touched on before, in a few different Threads.
The Classic, and most other CCs generally use screw terminal connections fot PVs and the battery cable.
These terminals are really designed for coarse-stranded cable. THHN, and other similar cables fall into this category.
Almost NO Fine stranded cables are designed for this type of terminal connection. Fine strand cables should not be used.
Was unable to find the Anchor stranding spec for their #4 AWG cable, but did see some #6 gauge that had about 261 strands -- this would seem to be inappropriate cable for almost any screw terminal.
It is fairly common to use a short piece of THHN cable, up to #4 AWG size, and then make the transition to fine strand, if you choose, at the battery circuit breaker, using standard APPROPRIATE crimp lugs on a breaker with stud terminals. Of course the correct lug must be used to match the stranding and design of the cable.
Just being a bit redundant. FWIW, Vic
What Vic said...
Try one of these guys maybe....
http://www.ferrulesdirect.com/
https://www.digikey.com/products/en/connectors-interconnects/terminal-blocks-accessories-wire-ferrules/364?k=ferrules&k=&pkeyword=ferrules&pv1989=0&FV=ffe0016c%2C5800996%2C580021f%2C5800229%2C580022d&mnonly=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25
boB
Anyone know what size the hole diameter actually is?
Is there an actual spec on the existing terminal block for what wire it is designed and qualified for?
I read the manual and spec sheet, but perhaps missed it.
So, it appears that the hole diameter is approx 0.25 inch max - with 0.23 inch being a more comfortable fit.
I sliced through a lug on the existing wire and even with a thin ferrule it would be 0.30 inch.
Guess I will keep looking.
Thanks for the help - much appreciated.
Quote from: 5 Minutes 2 Midnite on May 06, 2017, 09:11:14 AM
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
Quote from: ClassicCrazy on August 28, 2017, 05:45:19 PM
Quote from: 5 Minutes 2 Midnite on May 06, 2017, 09:11:14 AM
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.
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
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.
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...
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
Yeah, seen some references to that. Site has a clunky search. Perhaps this should be a sitcky.
yes i agree the search function is totally useless
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
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.
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.
Quote from: australsolarier on April 25, 2018, 12:06:33 AM
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
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...