Bus bar chamber with no main isolator

[AH86Spark]

Evening, I've been asked to install a supply to a sprinkler system in a new installation that must be separate to the building electrical services. I.e if you isolate the building to work on the electrical services then the supply to the sprinkler pumps must remain live.

The only way I can see of doing this is to install the tails from the 200A service fuses to a bus bar chamber, feed the building panel board from that and also feed the sprinkler switch fuse from that. However, I am uncomfortable with the bus bar chamber having no isolation other than the service fuses

Is there an alternative way??

 

[MDJ]

It is common place for busbar chambers to be connected direct to the main switch fuse supply into the building, usually then all sorts of different rated switch fuses are coupled to the chamber and then submained from there to the equipment they were installed for, I have seen literally hundreds over the years like this. That said in your case why cannot you fit a panel board direct to the supply switch fuse and then use an MCCB for the new sprinkler system and MCCBs for the distribution boards inside the building? this way when you need to shut down you can isolate all the MCCBs at the panel board and keep just the MCCB for the sprinkler system working? Unless I have mis understood your post this doesn/t seem a difficult issue to solve.

Any Pictures of the existing set up?

 

[Marvo]

Busbar chambers are often considered what's often termed as 'fault free zones' as per BS EN 61439 where firstly the primary purpose of protection is to prevent the possibility of short circuit faults and physical injury to personel by construction techniques rather than preventing overload of conductors by OCPD's.

See attached quick guide for some basic info.

The type of circuit you refer to for fire sprinkler booster pumps would usually be specified in detail by the electrical engineer responsible for the building electrical reticulation.