Coding muddled circuits

I would deem in Code 2 but might suggest that if a warning notice was placed at the DB then a Code 3 would be appropriate.

as a matter of interest, if my guys are dead testing in domestic premises then all boards must be locked off. The lady would have to find a WiFi connection by some other means.

So the problem is that the label should have read "upstairs & outside lights" rather than just "upstairs lights"? For me that's no more than a C3.


The other side of the issue might be described as a lack of proving dead...


   - Andy.

I think we have all been there, some of us have a pair of cutters with a bit missing to remind us to isolate the right circuit, and then to double check - even if for the DIYer it is as simple as turning the lights on before pulling the fuse and then checking they have gone out before opening up the fitting.


Had it been labelled 'lights one' and 'lights two' or completely unlabelled then that would have been fine, as it would have forced you to check ,as quite often lights are 'original house' and 'extension' on two circuits, rather than up and down.

I fear you have to chalk it  to experience, and to scrawl  '& outside' in sharpie or soft pencil if you want to protect the next guy in. In terms of code it could be C3, it is only dangerous because you have the installation in bits, and that is neither normal operation nor a fault.

Ah,sorry, I read the OP as a borrowed neutral situation. So, I review it to no code on the basis that only electrically skilled persons should be gaining access. Adjust with sharpie as per Mike.

I would struggle trying to justify a C3 I am afraid. After all, the other lights aren’t individually named on the description. This is where a circuit chart next to the CU wins, as you have room for much more description.


One for experience I think, and you are still with us to carry on. I have a poster behind my desk that says something like “Prove Dead - Stay Alive”. 


Regards,


Alan.

Perhaps a useful tip which I gained from Western Power recently. Their jointers seem to wear normal blue neoprene gloves for all work. These provide 230V insulation (avoiding your snag Chris) without any trouble as long as not mechanically stressed too much and save many tingles which might otherwise occur. Much work is live, and proper insulating gloves are far to cumbersome for many jobs, and insulated tools are not always 100% ideal but the gloves provide a second layer of safety. No guarantee from me, but it does help! I have tried the slightly thicker orange ones (Motor factors supplied)  and these are pretty good too.


No code please Chris, where does BS7671 say that unscrewing a switch plate is safe, it often is not!

No code please Chris, where does BS7671 say that unscrewing a switch plate is safe, it often is not!

Although BS 7671 does require protective devices and isolating devices to be properly identifiable (514.8 & 537.2.7) - the lack of which was the root cause of the problem in this case, so certainly a non-conformity to BS 7671 to my mind.


   - Andy.

That Andy is probably going a bit far. One could identify the lighting circuits, so if necessary ALL should have been isolated. If you continue this through,it suggests that full plans should be available, particularly for larger installations, which almost never happens, and even if they are there they are often incorrect or the installation has been modified. Isolation of a light switch is easily checked with a voltage detector. What you are suggesting is in effect trying to change the EAWR to make a possible accident to someone else's fault. This is NOT sensible although yet more stuff for lawyers to play with.

Gentlemen, thank you for your comments.


As I wrote at the beginning, it isn't quite what happened, and it was just a little kiss across the hand; but the cables are such a muddle that I should have known better - at one time the kitchen sockets were supplied by three different circuits!


Before I did my training, I once very nearly poked about in the wrong junction box and I now prove dead before undoing anything in one of them.


The reason that I mentioned a broken switch in my scenario is that if one cannot turn on a light (or something audible like a vacuum cleaner plugged into a socket) one cannot use Mike's method to confirm isolation.


Perhaps BS 7671 simply doesn't cater for this situation, but simply adding loops and spurs to the nearest circuit willy-nilly really is not good practice.


It won't happen again (a) because I am re-wiring the place; and (b) I shall be more careful in future. How embarrassing! ?

HI Chris


I'm willing to bet we have all learned the same way - by making mistakes sometimes.


Small Mistakes. Small mistakes are minor miracles sent to teach us to watch out. (We've all had them)


Not my way to do things but - Lighting circuits are often run between household floors especially on the stairs and landings. Outside lights can be supplied from either circuit. Sockets; always expect the upstairs/downstairs divide to be violated at some point; if the house holder was refurbishing the lounge umteen years ago - and he/she want to add a socket in the bedroom - maybe it was easier to extend from the ground floor up to the bedroom for example. 


Isolation of a single circuit with multiple items on that circuit (Such as DSSOs) = don't assume that this item (eg: DSSO) is on the isolated circuit if you cant see every cm of its run......... assume it is on a different circuit.


And most importantly of all - and the hardest lesson to learn - is watch out for the shared neutral circuit. That'll make a revelation of your thinking. Most especially when you "isolate" a single circuit while leaving other circuits live. 


A fluke "wand" (a volt stick I think its called) with audible warning is my most recommended bit of check kit for small stuff.


The end flashes to shows its on and turns solid with an audible beep when it detects an electrical field. (Not be relied on as a sole form of proving dead but useful to back up a very sure assumption - after checking with the ol volt meter of course)


Even with the DB main switch off, assume that the neighbours house electrics have crept into your property over the last century and wave the wand around before cutting/working on the cabling.


Certainly if you ever get into a large office kitchen or commercial kitchen, there will be multiple circuits that supply that lot. 


Kind Regards