I have a project where the facility has a 4000 Amp RL Siemens Switchgear lineup as part of a double ended substation. The gear is fed from a 2000KVA transformer and the available fault current is about 69kA at 208 volts. The 4000 Amp main is rated 85kAIC but some of the feeders are rated 30kA for example: A Siemens RL-800 feeder breaker. What is the short circuit current rating for this switchgear? Conventional wisdom would state that the switchgear is rated for the lowest rated device in the switchgear. Does any one know which standard states that the switchgear would be rated for the lowest device? Is it possible that this switchgear is not over duty? I am going to need to reference the applicable standard to explain why I think the switchgear is over duty.