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 24 replies
  • Subscribers 32 subscribers
  • Views 2949 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

The Downing Street problem

AJJewsbury
No, nothing to do with politics - just earthing and bonding - just recent events have perhaps given us an interesting example.


As I'm sure everyone has noticed of late, No.10 Downing Street has a nice electric lamp for its front door - supported by an arch from the iron railings. Similarly, immediately next door to the left (contrary to usual UK practice, designated No.11) also has lights fixed from the railings - two in this case, at least one of which appears to share the same railing system as No.10.


If pictures help: No.10 and No.11


For the sake of this discussion let's assume No.10 and No.11 have separate DNO supplies and the light fittings are all Class I.


If you had to do the design for feeding the lights outside either or both premises (and had no ill-intent to the occupants) what sort of earthing and bonding arrangements would you specify? (and would regulation 714.411.3.1.2 figure in your thinking?)


  - Andy.


Parents
  • 0
    Same as you do when houses share a common water main but are on different substations - both will be bonded, the unusual thing here is that it is visible, but an equivalent connection exists in every housing estate large enough to support more than one substation.

    I strongly suspect that in this case however, there is also more than one source of supply to no10 alone. If the outside lights are backed up or not I do not know, but I'd expect a at least some of the equipment to be worth keeping on during a power cut.
Reply
  • 0
    Same as you do when houses share a common water main but are on different substations - both will be bonded, the unusual thing here is that it is visible, but an equivalent connection exists in every housing estate large enough to support more than one substation.

    I strongly suspect that in this case however, there is also more than one source of supply to no10 alone. If the outside lights are backed up or not I do not know, but I'd expect a at least some of the equipment to be worth keeping on during a power cut.
Children
No Data

Community Rules & Guidelines