Reversed Tails at Board

[wicksygas]

Apart from swapping them over, what would you do if you came across Live & Neutral tails reversed at the consumer unit?

 

[littlespark]

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.

 

[timhoward]

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.

 

[littlespark]

it looks to me that the B40 mcb is being fed FROM the rcd in question... and another rcd feeding the next lot of breakers.

 

[timhoward]

Deleted

 

[timhoward]

it looks to me that the B40 mcb is being fed FROM the rcd in question... and another rcd feeding the next lot of breakers.

Yep agreed. I deleted that bit in the meantime

 

[timhoward]

My eyes really aren't working tonight.
We seem to have an S type 100ma RCD main switch, then a downstream 30ma RCD?

 

[wicksygas]

Can we see photo of other end where (presumably) the main switch is too please?

 

[wicksygas]

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.

 

[pc1966]

Unless the DNO head is wrong, that is a C1 fault for reversed polarity!

Have you actually checked the polarity at the CU? (i.e. L-E has 230 volts, N-E practically none)

 

[timhoward]

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...)

 

[pc1966]

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.

 

[7029 dave]

As above if reversed polarity is confirmed you must correct it.

 

[Dave OCD]

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.

 

[-Matt]

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!!!