DC Bus bar clearance

[qstorm]

We are conducting a retrofit on our DC switchgear (750V railway) and additional bus bars will be installed. However, due to space restrictions we have an issue on the allowable clearances between the positive or negative bus bar and the enclosure or any metallic support. Please enlighten me on the allowable clearances.
TIA

 

[alehman]

It depends on where you are and what codes apply. UL 891 would require 1 inch.

 

[Warpspeed]

And you can always pack some suitable insulating sheet between the bus bars where they are fairly close. This is often a good idea anyway, because it prevents things falling directly across the bus bars, while still allowing adequate cooling.