Tie breakers and cable

[wbd]

I have a situation where there is a tie connection between two 480V buses. The tie consists of normally open breakers on each bus and 2 conductors per phase of 500mcm CU GE Vulkene insulated conductors. In my experience, I always thought it was prudent to keep the cable energized by haven't one tie breaker be normally closed. This way the health of the cable is known as cable fault would trip the breaker. With the tie breakers both open, the integrity of the cable would not be known until the tie is needed and breakers closed. There is a Kirk key system on these breakers.

Thoughts?

 

[davidbeach]

Ideally one breaker would always be closed. As you note, if it isn’t energized you don’t know anything about it.

 

[dpc]

I think this is generally standard practice, although there are arc-flash implications for a fault in NO tie breaker.

 

[crshears]

One NO and one NC is the convention, and the one I would design for.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]