Kitchen wiring advice please

[GaryMo]

If you followed that test exactly and didn't just measure end to end resistance of L, N and CPC then that's a step forward.
You now need to confirm conductor sizes and if any cables pass through any thermal insulation or are housed in trunking or conduit.
Each cable on a 30/32A ring final should have line and neutral conductors not less than 2.5mm (apart from MICC and must be capable of carrying a minimum of 20A under their installed conditions.

 

[ban-all-sheds]

Possibly - it depends on the circuits Zs value.

And whether any of the cables need derating because of installation method or grouping or ambient temperature factors.

And whether you've confirmed that there are no unfused spurs supplying more than one socket.

 

[GaryMo]

Possibly - it depends on the circuits Zs value.

I nearly put that but now as we're living in a world full of RCD's it doesn't seem so important anymore. Still, I'll always aim to be within maximum values for the MCB.
Volt-drop, on the other hand could be a factor.

 

[ban-all-sheds]

I really don't think that the presence of an RCD means you no longer have to worry about fault loop values......

 

[GaryMo]

I really don't think that the presence of an RCD means you no longer have to worry about fault loop values......

I meant within reason, as in exceeding max value for a B32 BS EN 60898 MCB by half a ohm or so. I should have elaborated and not given the impression that it could be infinite.
A 30mA RCD will allow a max loop impedance of 1666ohms (50/0.03) before touch voltage rises dangerously above 50v so unless the suppliers earth has gone missing or there's a fault on the cable (he says he's checked the condition of the ring) there shouldn't be a problem.

 

[nelo]

As far as i can tell all cable on the ring is 2.5 mm and passes through a short section of trunking from the CU to the ceiling, and there is no thermal insulation for it to pass through. The circuit consists of 6 double and a single socket, and no spurs fused or unfused. The area that it serves is quite small too, the house in a small terraced

 

[ban-all-sheds]

I wonder how a 2.5mm² ring final came to be on a 16A breaker....

 

[nelo]

It appears that the 16A wa previously used for the emersion heater and now there is no emersion someone previosus to me has utilised it for downstairs ring. What kind of problems might i get with the ring being on a 16A. Will it just simply be tripping the MCB when more than one appliance is on?

 

[ban-all-sheds]

It's more likely to trip with increased loading than a 32A....

 

[nelo]

Thanks for all the advice. Its a big help. Muchos Gracias