What is going on here?

[Gyro]

Don't know if it's my imagination, but there looks to be less visible thread length above the nut and the tab doesn't look to be flush with the buss bar (hard to see). I don't suppose it's possible that someone put a washer underneath it?     Maybe it's just a thicker tab compared to the one on the right.

[AF6LJ]

I have two words for you......

  Ohms Law

[/b]

[jlmoon]

That red nut is a "POWER ON" indicator.   

[Kintekobo]

What I find puzzling about this picture is why is just the nut glowing cherry red when there should be little or no current actually flowing through the nut since it is above the current path. The current should be flowing through the cable to the terminal and then to the bus bar. For the nut to be that hot would suggest that there is no or poor current path between the terminal and the bus bar and all of the current is travelling up, through the nut and into the bolt and then to the bus bar.

[AF6LJ]

There is a gob and a bunch of If's and What-if's implied in the picture.

The picture does have a certain "coolness factor" going on with it.

[jlmoon]

What I find puzzling about this picture is why is just the nut glowing cherry red when there should be little or no current actually flowing through the nut since it is above the current path. The current should be flowing through the cable to the terminal and then to the bus bar. For the nut to be that hot would suggest that there is no or poor current path between the terminal and the bus bar and all of the current is travelling up, through the nut and into the bolt and then to the bus bar.

I am venturing to guess on this one:  Yes the nut is above the path for current... but is it really?  Especially if the joining surfaces between lug and bus bar are high in resistance due to state changes in conductive surfaces.  The Nut could be "Dicks last resort" for a current path that is from top surface of lug through washer into nut and back to bus bar via threads of stud.  Possible?.. Yes!!!

and I read back a few post and Catiline..... had the same exact explanation. 

[jlmoon]

I have two words for you......

  Ohms Law

[/b]

Is it my tendency of overkill or shouldn't the conducting surface area be close to or equal to the cross sectional area of that current carrying conductor?  Not sure but think the stud, lug, washers & nuts could be a size or two larger. 

[Kintekobo]

jlmoon[size=78%], I would agree with you there. That is one hell of a thick cable but it ends in a fairly insubstantial lug. Unless of course the cable is thinner than it appears and is covered with a very thick insulation making it look thicker than it is. Somehow I think it is the former rather than the latter judging by the heat [/size]generated.

[AF6LJ]

I have two words for you......

  Ohms Law

[/b]

Is it my tendency of overkill or shouldn't the conducting surface area be close to or equal to the cross sectional area of that current carrying conductor?  Not sure but think the stud, lug, washers & nuts could be a size or two larger.

That picture leaves a lot to question, under good conditions those nuts and studs look large enough. At the same time both of the large wires show heat damage, it could be from the one bad joint, or not.

Actually this picture is a prime example of why a picture is worth a 1,000 words.
So much speculation.

[Gyro]

The more you look at that photo, the more you see...

From all the blue wires I assume it's a Neutral Bussbar (those live brown wires at the right look a bit close considering how hot it must have been).

Curiously the wire that is snipped off on the first visible tag on the left had BROWN insulation 

[tron9000]

The more you look at that photo, the more you see...

From all the blue wires I assume it's a Neutral Bussbar (those live brown wires at the right look a bit close considering how hot it must have been).

Curiously the wire that is snipped off on the first visible tag on the left had BROWN insulation 

Dear god! yeh! what the hell is this butchery?!