toasted buss bar & wire

[mike90045]

XW6048 epanel
Been getting high battery voltage alarms from the charge controller, and I went over all the battery interconnects and the terminals in the charge controller with an IR thermometer.

Then, when getting into the ePanel, to prep for the Midnight Controller for the new array, I saw the cause. And all the screws seem tight. Putting in new #4 wire (55A) and buss bar, and that should fix it up. Yow!

So, it would seem that #4 coarse wire would be ok in the buss bar.  Is this a correct assumption ?  Screws were in tight. Till the new bar is here, I'm not messing much with it, as this is a live system.   Any suggestions about conductive copper filled greases for the wires ? 

more photos here  https://www.facebook.com/photo.php?fbid=000000000000000&l=8bc17afb6c

[Vic]

Hi Mike,

WOW,  that is UGLY.

You are a technical person,  but,  as you know,  these connections must be very tight,  allowed to rest and then re-torqued.

Have never had this problem,  but charging batteries can create a lot of stress on components,  because it is often a long slog.

Have never used any conductive goop on these connections,   BUT,  would think that NoalOx or very similar compound should not hurt -- any anti-oxidation material intended for electrical connections should be OK.

So these cables had clean and bright copper at the connection to the busses when first installed?

This situation simply has to be the result of contact resistance at the buss connection -- normally torqueing to spec,  and repeating a day or so later should be fine,  unless the cables are far under-rated,  which from your post,  they should not have been.

The additional pics unavailable -- am not a Face-Space member.
Dunno.   Good Luck!     Vic

[Resthome]

I'm curious as to what the yellow label in this e-panel is saying. It seems to indicate, although most of it is blocked by the wring, that fine stranding wire be used for something. Anyone know what the complete label said.

And yeah the FB links don't work.

[Westbranch]

I think I have the same sticker in mine , poor pic attached but readable.

Mike, Just saw that the upper wire is getting black corrosion and charred insulation  too...

[Resthome]

So according to the label the Battery cable are suppose to be fine strand cables such as the Cobra cables. Those cables on the Battery Plus bus bar are not fine strand cables.

[Westbranch]

John, you're comment made me look...  wow, look at the strand #'s on these battery cable s

http://www.cobrawire.com/products/battery.php

[RossW]

So according to the label the Battery cable are suppose to be fine strand cables such as the Cobra cables. Those cables on the Battery Plus bus bar are not fine strand cables.

10 years ago when I made my battery cables (only 35 sq mm about 1AWG), I used a superflex cable, like this:


I had ALMOST gone to the red stuff in this picture, but the cost was prohibitive...

[Halfcrazy]

So according to the label the Battery cable are suppose to be fine strand cables such as the Cobra cables. Those cables on the Battery Plus bus bar are not fine strand cables.

That label is referring to the big cables that go to and from the breaker to the inverter. Not to that bus bar. We do not want people trying to run 2/0 or 4/0 THHN to the breaker as it would be brutal for them and tough on the breaker.

[Halfcrazy]

I should also point out this is a point of confusion as the little terminal bus bar is labeled "Battery Positive" and it is battery positive but for things like charge controllers or loads not the actual battery. I wonder if a label change may be beneficial. Maybe something like "Battery + for Accessories"

In this particular case this was not the issue but I have seen 3 or 4 people wire there battery to that little bus bar with #4 or #6 thhn and wonder why things melt when the XW draws 6KW.

As seen in the attached picture the Red arrow depicts "Battery positive" and the Green Arrow depicts "Accessory Positive"

As you can see you would not want to try to hook 4/0 THHN to that breaker but in the other side #4 THHN is perfectly manageable to the Accessory bus bar

[ChrisOlson]

When terminating stranded wire in a screw type bus bar you should insert the wire into the smallest hole it will fit in and use a ferrule or tin the wire to prevent damage to the strands.  The process of tightening the screw "grinds" on the wire strands and reduces their cross-section.  If you damage the strands, the termination will not handle the full ampacity of the wire.

It is also difficult to keep the connection tight after it thermal cycles a few times when the strands are damaged and squeezed out to the side of the screw as shown in the photo.  Tinning the wire prevents that.  The screw will "bite" into the tinning and make a good contact surface area to the bus bar, but the tinning will prevent damage to your wire strands.

I'm not sure if tinning meets code for commercial installations (I don't think it does) where stranded wire is terminated in a screw type lug.  But ferrules or Anderson contact lugs do meet code.  For me, tinning the wire has always worked fine and insures a maximum contact wire termination that will stay tight with thermal cycling.  I've had inspectors look at some of my installations and they never said anything about the tinning on the wire.  So I think tinning the stranded wire is "good enough" for the poor man doing his own installation.  I think an inspector would only question it if it happened to burn off and then he'd look at it and go, "Oh yeah - there's your problem - you tinned it instead of using a ferrule."

[Resthome]

That label is referring to the big cables that go to and from the breaker to the inverter. Not to that bus bar. We do not want people trying to run 2/0 or 4/0 THHN to the breaker as it would be brutal for them and tough on the breaker.

That makes more sense. Thanks for the clarification, Ryan. It wasn't clear what terminals the label was referring to.

[Resthome]

When terminating stranded wire in a screw type bus bar you should insert the wire into the smallest hole it will fit in and use a ferrule or tin the wire to prevent damage to the strands.  The process of tightening the screw "grinds" on the wire strands and reduces their cross-section.  If you damage the strands, the termination will not handle the full ampacity of the wire.

It is also difficult to keep the connection tight after it thermal cycles a few times when the strands are damaged and squeezed out to the side of the screw as shown in the photo.  Tinning the wire prevents that.  The screw will "bite" into the tinning and make a good contact surface area to the bus bar, but the tinning will prevent damage to your wire strands.

I'm not sure if tinning meets code for commercial installations (I don't think it does) where stranded wire is terminated in a screw type lug.  But ferrules or Anderson contact lugs do meet code.  For me, tinning the wire has always worked fine and insures a maximum contact wire termination that will stay tight with thermal cycling.  I've had inspectors look at some of my installations and they never said anything about the tinning on the wire.  So I think tinning the stranded wire is "good enough" for the poor man doing his own installation.  I think an inspector would only question it if it happened to burn off and then he'd look at it and go, "Oh yeah - there's your problem - you tinned it instead of using a ferrule."

+1.

Excellent advise Chris. I tin mine also. Adding the ferrules is great but doesn't always work unless you have a larger hole available in the buss bar.

[Westbranch]

Any recommendations of ferrules? As my pic shows there is not much room in a standard width E-panel...

[Resthome]

Any recommendations of ferrules? As my pic shows there is not much room in a standard width E-panel...

I'm not using and e-panel here but from the pictures you're correct not a lot of room. You also have to use the correct crimpers with the ferrules.

http://www.ferrulesdirect.com/electrical/WIRE_FERRULES.htm

[zoneblue]

I agree that screw type terminals have issues, and i try to avoid them altogether for anything carrying any current. Crimp, lug and post is a better solution.