NEC 450.14 - MV Transformer Disconnecting Means

[bdm5066]

I have a project (still in the design phase) where we have 28kV switchgear that distributes power to multiple unit substations (transformers close coupled to 480V switchgear). We currently show a disconnect switch connected to the primary of each 28kV-480V transformer (to satisfy NEC 450.14).

The client has asked us to remove the disconnect switch from our design in an effort to save money. He argues that racking out the upstream MV breaker counts as locking out the disconnecting means. He references the exception in 450.14 about how you can have a remotely located disconnecting means, but it has to be lockable.

I'm not sure if I'm convinced that racking out a breaker is the same thing as a lockable disconnect switch. What does the group think?

Thanks in advance for your thoughts.

 

[jim dungar]

Most MV breakers can be padlocked in the withdrawn position. I have seen many LOTO programs that rely on this feature.

 

[don_resqcapt19]

It is common to rack out a breaker and use a lock to prevent it from being racked back in as the lockout method.

 

[bdm5066]

Makes sense! Thanks for the responses!