Unfused busbar tap-offs

What is protecting the bus bar, and would it be acceptable for it all to lose power together due to a fault in one circuit fed by an unused tap?

If the fuses or breakers supplying the busbar co-ordinate with the protection required for the cable, it is certainly possible.


The convenience of it being broken up in terms of isolation for finding  faults, or indeed to shut off one branch for repair, and keep the rest energised is lost, but this may be acceptable.

Provided you can accept the possible loss of discrimination (a fault on any consumer unit tap off will kill off the busbar) then provided the busbar infeed cable, the busbar itself and the tap off outfeed and consumer unit rating all meet or exceed the rating of the OCPD, then happy days


Keep in mind that this is exactly the scenario that leads to small overloads of long duration - so be reasonably generous with the cable sizing against whatever diversity you've applied to the busbar loading in relation to the room loads


Regards


OMS

Un fuse Bus bar tap offs can fix but should have a fuse or Mcb next to each tap offs


When this Bus bar system Design 1st step is must workout the total reqired  current capacity of the relevant building after that you must identify the required current  capacity  for each consumer in according that you can suggest the fuse or Mcb current capacity  ***  ,be care full to select the Mcb rang not exceed over than 5% of actual current required to the consumer

You don't say what the CU in each room is equipped with.

The requirement is that overload protection can be before or after the cable being protected (but short circuit protection must be before).

This means that if the CU has an incoming breaker or if the total of all the outgoing breakers on a CU is less than the cable rating then the TEE off is protected against overload at the destination end and does not need protection at the source end.