down a hole fixing a cable

I'm in a trench being attacked by flies that want my blood.

The cable is a 4mm csa 3 core SWA, new colours.
The cable is burried 1.5m in made up ground behind a wall built of sleepers .
There is yellow tape 0.1m above the cable.
The Run is about 70M

The supply was switched off, so dispite having a detector and knowing there was a cable there some where in there, the digging team didn't have a chance.
The property is locked, the location is remote.
The digging team are laying a pipe and back filling as they go.
They have stalled.
So here I am with submarine kits to patch it up so they can carry on.

I check the ends with a test meter, volts against the ground I'm in first.
All dead.
Then resistances,
on the sink end 31.3ohm between Brown and Black, 0.67ohm between Grey and armour. 1.17Mohm between Brown and Grey.
On the source end
>50Mohm between Brown and all others,
0.09ohm between Grey and armour, 0.08ohm between grey and black.
From these readings I take the following guesses.
The supply system is TNCS and is live.
If there is an RCD it did not trip but may still trip if I short the black and grey.
Only the supply circuit breaker or fuse is out.
The load is about 7A single phase
The spark who connected the system used the grey coloured cable as a cpc in parrallel with the armour.

So whilst I 'm waiting for the resin to cure and hoping not to have to come back when they key holder is found, I'm thinking..
In the good old days when we used red blue and yellow it was obvious which conductor to use for single phase cpc and which for the phase and neutral. These days it is not so.
And the question is, which colour do you choose for a cpc on a single phase system wire in three core brown black grey?

I use grey just to annoy those that think you cant use the black as a neutral anymore

Grey = neutral
Black = CPC

You can use any you wish as long as it is correctly identified. Even on the old colour system there was nothing cast in stone to say the yellow can be utilized as the cpc, people saw yellow as being akin to green/yellow and blue as neutral as in flexible cables/cords with the yellow occasionally sleeved and the blue left unidentified when it should have been black.

as above. now the yellow is black (L2) then it's common sense to use black as cpc ( suitably sleeved).

Grey-neutral
Black-CPC
All cables must be identified each end and at any JBs along the way...
and try to get an easier job next time!
Who needs plumbers, builders, owners, breathing down your neck, while not having proper access? F**K THEM ALL! Stand your ground, take a breather, remember you are the true professional!

pirate said:

Grey-neutral
Black-CPC
All cables must be identified each end and at any JBs along the way...
and try to get an easier job next time!
Who needs plumbers, builders, owners, breathing down your neck, while not having proper access? F**K THEM ALL! Stand your ground, take a breather, remember you are the true professional!

Click to expand...

Where is that conductor usage stated?

Sounds a straightforward enough job.
Them wagos are good for anything, these days...

ipf said:

Sounds a straightforward enough job.
Them wagos are good for anything, these days...

Click to expand...

Dry spell, should be ok for a bit

I think green/yellow looks better on black
and blue looks better on grey.
but always verify with tester, never trust a bit of tape.
Don't mind clients and other trades standing and watching,
just charge more for the instruction.
wiska submarine plastic cases are a bit brittle when trimming the ends to fit the cable, bring a junior hacksaw next time.
WAGO blocks and self amalgamating tape no good underground
had to dig up a joint like that last week

JK-Electrical said:

I prefer to use SWA that comes with brown, blue and green/yellow conductors:

Superlec 3CORE 4MM SWA BS5467 STEEL WIRE ARMOURED CABLE BRN/BLUE/GRN YW CORES - https://www.superlecdirect.com/cables-and-accessories-c1/bs5467-steel-wire-armoured-cables-s6/p-xlpe2ex4-superlec-3core-4mm-swa-bs5467-steel-wire-armoured-cable-brnbluegrn-yw-cores/

Click to expand...

Brown/Black/Grey has more uses though.

4 core has even more.