How stupid is this?

[Q-Dog]

In this case, they actually do.
Look at the picture again.

One of mine did too.

 

[Hedges]

In this case, they actually do.
Look at the picture again.

I was thinking of "C" shape, or twisted to accomplish it.

But you're right.
I'm getting slow. Not sure if it is due to Long Covid, Long Vax, or Long Electrocution.

 

[kolek]

The copper bus bars are quite okay.
I would skip the brass bolt.
The bolt is there to just clamp.
Go with stainless bolt and nut. Remember a locking washer before the nut.

I'm curious why you dislike using more a conductive lug/nut?

 

[kolek]

The manufacturer recommends stacking them for more capacity.View attachment 211216

@Q-Dog Wow so that proves doubling up busbars is not stupid. Thank you so much for posting that!!

 

[Daddy Tanuki]

You laugh but look at the number of posts in the Up in smoke section that are caused by bad connections!

truth... frank down in the PI was a victim of that I think, even though he was too hard headed to admit it.

 

[Daddy Tanuki]

@Q-Dog Wow so that proves doubling up busbars is not stupid. Thank you so much for posting that!!

as long as you torque them correctly I see no issues with doubling up. CALB and EVE sell buss bars taht are 5 leaves of copper so thats five piece stacked up. proper torque solves that particular demon.

 

[12VoltInstalls]

proper torque solves that particular demon.

I'm curious why you dislike using more a conductive lug/nut?

I have used stainless but elect to use Grade 8 bolts in this situation whenever possible- way more tolerance for heavy torque, and very tight connections do not increase resistance as much as they could.

Brass is less corrosive but is more likely to strip a thread.
Stainless galls and often breaks on attempting removal.
Steel will never have any practical issues unless your wrenching requires remedial psychological intervention.

A spritz of fluidfilm can oxygen protect copper-to-steel/zinc plate fasteners and slow galvanic issues

 

[Brucey]

A spritz of fluidfilm can oxygen protect copper-to-steel/zinc plate fasteners and slow galvanic issues

After the connection is secured?

 

[wpns]

I'm curious why you dislike using more a conductive lug/nut?

I suspect, as in my case, it's disliking a weaker nut/bolt combination.

 

[Daddy Tanuki]

I suspect, as in my case, it's disliking a weaker nut/bolt combination.

yep stripping out a soft bolt or screw sucks majorly....galling, inability to unscrew as it keeps deforming in different directions... eventually you get a bigger tool, then it's a hammer and lastly a plasma cutter or a chainsaw....

 

[Hedges]

I'm curious why you dislike using more a conductive lug/nut?

"The bolt is there to just clamp."
Only a fraction of current goes through the bolt, so conductive doesn't really help anything.

I suspect, as in my case, it's disliking a weaker nut/bolt combination.

Contact resistance depends on pressure.
Contact is just at a few high points.

Stainless galls and often breaks on attempting removal.

I've certainly encountered this in a number of situations.
Although not in the bolts for PV mounts, for some reason.

A grease or maybe threadlock could protect against it.
Acting as a lubricant, reduced torque or same tension, if near limit don't want to break bolt.

Dissimilar metals avoids the issue. But want both strength and corrosion protection.
One of my pool components had stainless mail thread, 3/4" long brass nut. Which eventually ground the threads off with repeated use dry.

Set screws in a safety switch, one was seized when I went to remove it. Maybe lubricant would have helped. Don't know if humidity did that, or if my tightening had ground through tin plating and exposed more reactive aluminum.

 

[Vigo]

I have avoided galling on stainless by using dielectric grease on the threads. They tend to have a lower torque limit than what we're used to for a given size of fastener, so you do have to be careful about overtorquing.

Adding parallel current paths ALWAYS decreases resistance. I know that issue was addressed but i thought it might be helpful to state a one-sentence rule about it.

 

[kolek]

I have used stainless but elect to use Grade 8 bolts in this situation whenever possible- way more tolerance for heavy torque, and very tight connections do not increase resistance as much as they could.

Brass is less corrosive but is more likely to strip a thread.
Stainless galls and often breaks on attempting removal.
Steel will never have any practical issues unless your wrenching requires remedial psychological intervention.

A spritz of fluidfilm can oxygen protect copper-to-steel/zinc plate fasteners and slow galvanic issues

Hmm, I don't have a spriz of fluidfilm handy, will a little dab of Brylcreem suffice?

 

[Hedges]

Adding parallel current paths ALWAYS decreases resistance. I know that issue was addressed but i thought it might be helpful to state a one-sentence rule about it.

I'll take that as a challenge. Let me see if "Always" might sometimes be wrong.

"Negative Resistance" comes to mind first. No, I don't think that is the exception which proves the rule, would decrease resistance further.

Consider measuring resistance of a conductor, and then connecting a thermocouple in parallel, generating a voltage which causes additional current to flow through the path. That increases, doesn't decrease, the resistance you see. (in one direction.)

 

[Vigo]

I think that would come down to how you define 'Paths'. I could add a path with a diode blocking flow, or add a voltage source in reverse polarity etc, but those seem like end-runs around the intent of the word 'path'. But i do take your point about being careful with always/never..

 

[Hedges]

The main consideration with parallel paths is current may not split equally.
That can result in one conductor failing, cascading to the others.
Or tripping breakers, if each conductor protected.

 

[hwy17]

The main consideration with parallel paths is current may not split equally.

Current will always split proportionate to resistance right?

Anyway, not a necessary debate. Terminal bolts don't need to be conductive, and if someone uses brass and it doesn't strip for them, that's fine too.

 

[Supervstech]

Yikes...

Yes, a single busbar rated for 300A is better than two bars rated for 150A sandwiched together... but two sandwiched together are better than ONE 150A bar.

I wouldnt use brass bolts here because torque is so important with parallel bars.

Clean ends, make sure torque is solid, and go with it.

 

[robbob2112]

So, parallel bus bars verse two cables of the same cross-section area, if the cables are crimped such that there is a cold weld at the end they are the same difference as the bus bars. Now if you stuff two wires into a single lug and eliminate the second connection so long as they cold weld.

That means the only thing that matters is the connection resistance. The thing I would be worried about here is the bars in the pictures are not flat or touching flat. Even if you torque hell out of it they won't be flat. Bending a single bar might be easy, two not so much. I would put a spacer under the Lynx to bring the connections up even.

Were it me I would just use wires instead of bus bars, easier to bend, single lug resistance.

And or course No-Ox-id on the connections

 

[12VoltInstalls]

After the connection is secured

Yes

Hmm, I don't have a spriz of fluidfilm handy, will a little dab of Brylcreem suffice?

i always have some in an aerosol can. It has limited applications but not so uncommon that I wouldn’t have some on hand. Messy nasty stuff and I hate it but it works!