Sub Distribution Board Types

It would be rare for an isolation switch of some sort not to be provided on a distribution board. After all, how is one supposed to change a breaker - do it live (rhetorical question)?

Exactly,

but do you know anything about this type of sub distribution board? I read it in Specs but don't know what they mean by it.

Thanks.

http://www.bing.com/search?q=distribution+board+types+&src=IE-SearchBox&Form=IE8SRC

Wonderful things, Search Engines.

Would there not be one incomer device (switch, MCB, etc) in the board which receives the incoming power supply? This then feeds a small busbar system on to which some MCBs may be plugged in. In this case, the incomer device would be the isolator....

It is quite normal in North America to have sub-distribution panel boards to not have a main overcurrent device in them. They are protected by their overcurrent device located on the main distribution panel.

In this case... their should be no neutral to case ground (bond) connection at the sub panel as the neutral to case ground is created at the main panel of the service.

Having a second neutral to case ground point at the second panel introduces a redundant path for fault current back to the source. Such a redundant path, because of impedance differences in the second path relative to the first, can cause a voltage potential to exist between the bonding systems during a fault event.