Tapping a parallel bus

[Coastalguy1]

I have an electrical inspector concerned about an arc flash potentional where a 1200amp parallel tap was made on an existing 3000amp 480v 3ph 4w switchboard. Tap was made on load side of bussing. Inspector said contractor should have provide spacers between the busses when taps were made. Has anyone encountered or had experience with this situation?

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[rcwilson]

By parallel busses do you mean two or more bus bars per phase with a small air gap between them? (Example: two 1/4" x 5" bus bars spaced 1/2" with copper spacers at all joints and terminations).

If the tap bus needs to connect to both bus bars of the main bus by sandwiching between them or using conductive spacer plates.

Or maybe the inspector was concerned about the bus bars not having enough bracing to handle short circuit forces.

But I can't see how spacers would affect arc flash.

 

[Coastalguy1]

By parallel busses do you mean two or more bus bars per phase with a small air gap between them? (Example: two 1/4" x 5" bus bars spaced 1/2" with copper spacers at all joints and terminations).

If the tap bus needs to connect to both bus bars of the main bus by sandwiching between them or using conductive spacer plates.

Or maybe the inspector was concerned about the bus bars not having enough bracing to handle short circuit forces.

But I can't see how spacers would affect arc flash.

Yes, two bus bars per phase with an air gap in the middle. Perhaps you can expand on the bus bar bracing comment.