Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 37 replies
  • Subscribers 32 subscribers
  • Views 5448 views
  • Users 0 members are here
Options
You may also be interested in
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

How to wire up a consumer unit

Arran Cameron

A semi-detached house has a prehistoric fuse box with rewirable ceramic fuses. It will shortly be replaced with a modern consumer unit. The existing circuits are:



 



1. Lights



2. Upstairs sockets



3. Downstairs sockets



4. Kitchen sockets



5. Cooker



6. Shower



 



The following circuits will be added to the consumer unit:



 



7. Central heating



8. Burglar alarm and CCTV



9. Outside lights



 



I have been informed that the best choice is a split load consumer unit with two RCDs and space for RCBOs. My intention is that circuit 8 has its own RCBO but what is the optimal way to allocate circuits to RCD A and RCD B? Also, should any other circuits have their own RCBO?


Parents
  • 0

    Sparkingchip:

    An installation with ten 30 mA RCBOs could have a couple of hundred milliamperes of current running around the plumbing and earthing system without any RCD trips, whereas as the budget installation with one 30 mA RCD upfront would have shut down. . . 


    . . . In a TT installation even with double pole 30 mA RCBOs a 100 mA RCD main switch serves a purpose. . . 




    Indeed, and I wonder how many overlook that. With 10 RCBOs, you could have something just short of 300mA of earth leakage, and nothing would operate, everything being within spec. In a TT system, that would give you a maximum earth rod resistance of 166 ohms or so. 


    Regards,


    Alan. 

Reply
  • 0

    Sparkingchip:

    An installation with ten 30 mA RCBOs could have a couple of hundred milliamperes of current running around the plumbing and earthing system without any RCD trips, whereas as the budget installation with one 30 mA RCD upfront would have shut down. . . 


    . . . In a TT installation even with double pole 30 mA RCBOs a 100 mA RCD main switch serves a purpose. . . 




    Indeed, and I wonder how many overlook that. With 10 RCBOs, you could have something just short of 300mA of earth leakage, and nothing would operate, everything being within spec. In a TT system, that would give you a maximum earth rod resistance of 166 ohms or so. 


    Regards,


    Alan. 

Children
No Data

Community Rules & Guidelines