Safe isolation - are you sure you are safe?

Nice one - I think that I would have got a belt.

A quick Zs before removing the old fitting is a very easy precaution, but if Colin had been intending to issue a MEIWC, he would have done that anyway. A polarity check (also on the MEIWC) would have revealed the problem too.

Problem is that an electrician might not issue a MEIWC for very minor work - it would reduce the profit margin.

I am puzzled by the diagram above. If the little grey rectangle represents the meter cabinet, there appears to be a N-PE connexion between it and the DB.

Well I was told long ago, to switch things off but to still work as if it is live.
And it does help.
Back in the previous century I replaced a hall light fitting  that was not working for someone, and I took out the downstairs lights fuse and had it in my pocket. (I know, but the isolation techniques of the past were different.)  Anyway I duly removed the hideous chandelier thing and it's frayed flex and fitted a modern ceiling rose and holder, and then at the end, put the bulb in. And flinched a bit when it came on in my hand !! 
The 'so and so' s  who had done the hall and landing switches had taken the live feed for the hall light from upstairs, and because the original fitting was defective it had not come on !.
A volt stick or even a neon driver (boo hiss) would have revealed that, and the same applies to 'Colin' which I hope is not his real name. 
Moral, Expect the unexpected.  - actually the wrong kind of line reversal can also leave you with live plumbing !.

Mike.

Well I was told long ago, to switch things off but to still work as if it is live.
And it does help.
Back in the previous century I replaced a hall light fitting  that was not working for someone, and I took out the downstairs lights fuse and had it in my pocket. (I know, but the isolation techniques of the past were different.)  Anyway I duly removed the hideous chandelier thing and it's frayed flex and fitted a modern ceiling rose and holder, and then at the end, put the bulb in. And flinched a bit when it came on in my hand !! 
The 'so and so' s  who had done the hall and landing switches had taken the live feed for the hall light from upstairs, and because the original fitting was defective it had not come on !.
A volt stick or even a neon driver (boo hiss) would have revealed that, and the same applies to 'Colin' which I hope is not his real name. 
Moral, Expect the unexpected.  - actually the wrong kind of line reversal can also leave you with live plumbing !.

Mike.

Pretty common back then. I still come across an odd one on older properties where they borrowed lives and neutrals on the hall and landing lights. RCDs don't like it if you connect across two of them

Gary

mapj1 said:

The 'so and so' s  who had done the hall and landing switches had taken the live feed for the hall light from upstairs, and because the original fitting was defective it had not come on !

I learned to tread very carefully when re-wiring my daughter's house. It was originally a pair of Victorian farm-workers' cottages and some of the circuits were arranged vertically rather than horizontally. So the light switch in the dining room, which supplied a lamp above a door to the garden was fed from upstairs. The kitchen sockets were supplied by three different circuits!

Of course the safest solution, which the article mentions, is to isolate the whole DB, but that is problematic when the householder is present in the building.

Any thoughts on the diagram above?