main tie man swbd questions

[anbm]

What is minimum amp. rating of swbd available in main-tie-main configuration?
Will the kirk keys always be at the two main breaker as default after the swbd was built?

 

[jim dungar]

I have seen 100A main tie main configurations.

Kirk keys are simply a design decision. I have seen several M-T-M installed without any interlocking at all.

 

[anbm]

I have seen 100A main tie main configurations.

Kirk keys are simply a design decision. I have seen several M-T-M installed without any interlocking at all.

What do you mean? The tie breaker was never closed?

 

[jim dungar]

What do you mean? The tie breaker was never closed?

I have seen installations that were not interlocked in any manner at all allowing all main and tie breakers to be closed at the same time. Qualified employees and reliance on checklists were the only things preventing improper operation.

 

[petersonra]

I have seen installations that were not interlocked in any manner at all allowing all main and tie breakers to be closed at the same time. Qualified employees and reliance on checklists were the only things preventing improper operation.

what is the worst that could happen if all the breakers were closed at the same time? Its all synched in anyway.

 

[jim dungar]

what is the worst that could happen if all the breakers were closed at the same time? Its all synched in anyway.

Unintentional paralleling is often not good. One issue is high fault current values. Another is unequal size sources and current division.
It kind of depends on if the M-T-M was intended for open-transition switching (as is common with key interlocked equipment) or closed transition (which often includes synch check circuitry).