Another Q.

Is tinning copper bus bars still a good practice?

Muthu
www.edison.co.in

" Cables termination to busbars - from bottom or from top? I personally think from top is better since the cable is not pulling down from the lug".
I have the following opinion for your consideration.
1.There is NO mention (from top or bottom), in the IEC or NEC. It dependance on the practicality and easy routing, room availability etc...
2. Attention: in either (from top or bottom), the cable should NOT be pulling up/down from the lug.
Che Kuan Yau (Singapore)

Tinning is still required for some equipment per relevant standards, at least in US, but it isn't universal. It's helpful to provide corrosion in hostile environments. Copper wiring in shipboard use is generally required to be tinned.

Edison, that is the same photo, inverted.
The cables are terminated on the basis of space available for routing.
Top or bottom has nothing to do with it.
In either orientation of the inverted picture, try to imagine the Red phase terminated on the other side, be it top or bottom.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

The only consideration I am aware of that apply to the example junction box are:

• minding minimum bend radius.
• keeping parallel runs the same length.

orientation of the lugs up or down is at the tradesman's option.

"Is tinning copper bus bars still a good practice?"
I have the following opinion for your consideration.
1. In general, for indoor DRY installations, tinning is NOT mandatary. It does NOT increase the current rating but additional cost. Note: Although tinned BB looks shining after prolong usage, but that is cosmetic of NO electrical value.
2. It is evident that marine classification rule books do NOT state that tinning of BB shall be mandatary, unless special cases. Note : marine boards are indoor but humid environment.
Che Kuan Yau (Singapore)

dpc - Thanks. I use silver coating in our shop. Long time since I saw tinned copper.

waross - Yes, I know, I was the one who did the inversion (rather poorly) as an example of top termination.

FacEngr - Thanks. Logically, from the top termination does not pull the cable from the lug.

Muthu
www.edison.co.in

If the weight of that much cable pulls the wire from the lug, it is time to re-train the craftsmen involved or get better tooling. A poor crimp will fail regardless of the weight on it.