Chaps,

Looking at a fault yesterday.
Two lighting ccts, upstairs and down.

In order to isolatate either cct it is necessary to switch off both MCB's.

With one or the other switched off, operating the stairs lighting causes dimmed/flickering of the lights.

I assume this is a borrowed neutral scenario?

Any other thoughts or input much appreciated.

Given that the place has just been decorated, is an acceptable fix to simply put both lighting ccts on one MCB?

S.

That's what i'd do under the circumstances Sherlock, they obviously don't want their new decorating bu**ered up! I do this on c/unit changes quite often when I find shared neutrals,

Dave.

If it requires both mcbs to isolate both circuits then it is more than just a borrowed neutral. It sounds more like the lines are linked together somewhere with some other mis-wiring of some sort ? (hall/landing switching might be the first port of call)

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Empty barrels make the most noise.

I agree with Ricicle - there's more going on there than just a borrowed N. I'm presuming they're not DP MCBs and the Ns are still supposedly connected during this flickering? I might guess a loose connection in L somewhere that someone's attempted to by-pass but taken the feed from the wrong circuit.
- Andy.

Lights dimming also suggests that a bit of series connection is going on somewhere - certainly not just a borrowed neutral issue as highlighted by Andy and Ricicle

regards

OMS

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Failure is always an option

It does seem more than borrowed neutral.

Referring to hall\landing lighting circuit,.either the decorator has taken pendant off\or disturbed and refitted the an unflagged neutral coloured switched live in the neutral of the pendant or he has trapped cables at the switches.
When they are dim knock the switches and see if anything happens.
regards
Antric