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Test and Test again.
Check incoming Blue to incoming Earth is 0v or negligible and incoming Brown to supplier Earth is 230v.
At that point, having triple checked everything, and all connections in CU and any sub boards I'd swap them.

Deleted 2nd bit - didn't spot it was an RCD on left.
 
take the original installer round the back and explain, harshly, why it might be frowned upon.


wheres the other end of the tails? Ive seen it when they only had brown, so used brown for both and taped the ends blue on the neutral, but not just swapped over.
Fed from main switch in 16mm T&E so no excuse there.
 
The main and most urgent question is the one @pc1966 just asked (and I asked earlier in post #3)
(plenty of other secondary questions there, like single insulated tails, what earthing system is, why the 100ma RCD, what the 40amp circuit is for...)
 
Apart from swapping them over, what would you do if you came across Live & Neutral tails reversed at the consumer unit?
Assuming they are swapped, then you MUST correct them!

Otherwise all of the OCPD (both MCBs and 13A plug's fuses) are in the neutral circuit and a L-E fault (N now being L) is a fire starter as no meaningful OCPD (beyond the 60-100A DNO fuse).

Here is it simple as there is an isolator to allow the CU to be powered down without a visit from the seal fairy, otherwise it would be absolutely justified to pull the DNO fuse to fix it (or call them and tell them it is an immediate fire hazard).

Even if both ends are swapped (so just wrong colours) it is still a serious risk going forwards because you can be the next change has a high risk of not verifying polarity. Even though it is a tick box on the EICR report, etc, etc. So to me even that case requires swapping to get it correct.

Plain cable with colours sleeves is easier to change ends without disconnection via coloured tape, but rare outside of 3-phase. Still in my book they should correctly identify cables of such importance.
 
Be careful! I came accross this on a job a few years ago, so swapped it back around.

However the boiler PCB board went BANG when i re-energised.

Seems plumber had obviously discovered the incorrect polarity, so rather than getting it rectified, he swapped the polarity in the FCU ?

So when i corrected the polarity at the DB, the boiler PCB then got reverse polarity!!!
 
That 16mm T&E is atrocious the way it's been left in the meter box. And I assume there's no main bonding requirements as the only earth to the CU appears to be the 6mm of the T&E.
I'm also intrigued by the S-Type 100ma RCD, whether it is there simply for discrimination, or because it's TT....in which case the 6mm main earthing conductor could conceivably support the bonding.
 
I'm also intrigued by the S-Type 100ma RCD, whether it is there simply for discrimination, or because it's TT....in which case the 6mm main earthing conductor could conceivably support the bonding.
We would need more of a picture of the supply end to see if that goes to a rod or is somehow attached the the supply cable/cut-out.

Being TT is the most likely explanation, but given how new the cut-out looks it might well be TN-C-S now.
 
Thank you for your replies guys.
Like you, I asked myself why? and triple checked everything, so swapped them back over.
As there is now no C1 and no place to record "rectified revered tails at board". Is there any need or requirement to report this to, either, whichever company may have made the mistake, The landlord, The tennant, or any official body?
 
Be careful! I came accross this on a job a few years ago, so swapped it back around.

However the boiler PCB board went BANG when i re-energised.

Seems plumber had obviously discovered the incorrect polarity, so rather than getting it rectified, he swapped the polarity in the FCU ?

So when i corrected the polarity at the DB, the boiler PCB then got reverse polarity!!!

This is exactly why I would not just swap them over.

I’d get permission/price approval from the landlord/agent before making any changes so that you’re not liable for any issues.

Could end up being an expensive favour.
 
This is exactly why I would not just swap them over.

I’d get permission/price approval from the landlord/agent before making any changes so that you’re not liable for any issues.
It is a C1 case though, the most serious category of errors listed for any inspection.

While obviously the owner/landlord should be informed, the choices for making it safe are somewhat limited - correct it, or power off.

Could end up being an expensive favour.
Realistically no normal equipment should be damaged by a L-N swap itself, as it either implies some failing in the insulation or it has some very unusual functional earth feature (like some RCBOs). That is the reason for doing IR testing L+N to E as all "live" conductors should be adequately separated from the CPC & Earth.

Doing a global IR check (so supply isolated, and L+N for all to E) would reveal odd functional earths as a low R (typically RCBO's functional earths look like couple 100k ohm-ish)

But you do raise an important point that all socket outlets, etc, ought to be checked with one of those plug-testers just to make sure that somebody in the past did not "fix" the reversed polarity at the CU by also swapping at some accessories.

I suspect if it came down to some claim for damages, you would have a very strong case against whoever installed the boiler, etc, in the first place as they broke the rules by installing against accepted electrical practices (i.e. failing to report or correct a C1 fault, and knowingly hiding it by a deliberate incorrect installation of the socket/FCU).
 

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