Consumer Unit Installation (electrical)

[MattFS218]

A few more scenarios, to help me asses the urgency in which I should move my Ground bar to behind the Main CB

In my current installation with MEN before my Main CB (on the hot side)...

Scenario 1, someone is stupid and somehow the Live and Neutral get switched around on my meter. In this case my ground would take as much electricity as it could possibly take from the Live, until the fuse (if there is any) on the meter breaks, or the meter blows up. Until the time the meter fuse brakes or blows up, all of the metal work of appliances with a ground hooked up to the MEN link will be live and able to kill upon touch.

Scenario 2, What happens if my next door neighbor is stupid and connects the live line directly to the neutral (lets assume s/he is really, really stupid, and simply disconnects both lines from his meter, and connects them together). In this case the same effect would occur because my ground is the path of least resistance from my neighbor's connection. Is there something else in the MEN system that prevents the current from a stupid neighbor flowing back to down my neutral? Again the live current flowing down my neutral will stop once my meter fuse or meter blows up.

Does this seem right?

So currently, since none of my appliances have a ground connection that is hooked up, I should be relatively safe, as long as nobody touches the copper grounding rod at the time between when the Neutral becomes Live and my meter's fuse blows or the meter blows up.

Are these accurate statements? (sorry to be asking so many questions, it's just i'm not 100% comfortable with this stuff).

Edited October 18, 2008 by MattFS218

[MattFS218]

Crossy,

I was looking over your diagram at http://www.crossy.co.uk/wiring/CU-2.jpg

and from a laymen's perspective (me), it seems that the diagram shows the MEN/PME link being connected to the Hot Side of the Main Circuit Breaker rather than what you are suggesting connecting it on the Cold Side, is this a change of thought since you made the diagram, or just an oversight. If you don't have time, I can fix the diagram for you in photoshop, since you've helped me so much

--matt

[Crossy]

Matt, don't panic

A direct L => N short at your neighbours will cause something other than your system to fry, probably the neighbour, there is a path back to the transformer via the main neutral.

You are correct about my diagrams, they were done before the implications of L - N swaps became as vivid as they now are. I'll fix them (got the original Visio files), thanks for the offer.

DONE. Note that only the split-service CU is changed, the regular unit with a combined Incomer/ELCB must remain as is if the the ELCB is to work correctly.

Edited October 18, 2008 by Crossy