Issues with racking in of Buckets on Siemens TiaStar 480V MCCs

[edienberg]

Has anyone out here have any experiences (good or bad) with the "racking" functionality of Siemens TiaStar MCC buckets (breakers or starters) particularly the larger size 4 and 5 starters?

 

[jraef]

Sizes 4 and 5 are problems for everyone. The stab assemblies are required to have very strong spring clips in order to maintain good consistent pressure on the vertical bus bars, even as they age. When the starters get large like that, the loads get larger and therefore the starting current is in play longer, which stresses the spring tension of the clips over time. So the compensation they use makes them more difficult to apply when inserting them onto the bus. The trade off is, how often are you removing and re-inserting size 4 and 5 starters?

"Will work for (the memory of) salami"

 

[dpc]

Unfortunately, MCCs in the US are practically a commodity item and nearly all suppliers produce similar stuff with a marginal quality level. If they did it right, they'd never sell anything because it would be too expensive and they'd be out of business.

You definitely want your arc-rated PPE when inserting or withdrawing ANY MCC bucket into any energized MCC, regardless of contactor size or manufacturer. Size 5 and larger starters are problematic for so many reasons.