Cooker and shower on the same circuit

So? It's a general Triton video aimed at the house owner so they know roughly what to expect when considering getting an electric shower, not a detailed discussion of requirements for an experienced electrician. If you really want to interpret that as strict manufacturer's instructions, then by all means take those instructions into account when designing the circuit.

Going back to your 10.00mm2 shower cable. What is it rated at if using installation method  101? Are you then going to use a 40 Amp protective device? And by the way, the manufacturer's installation instructions are aimed at any installer. They looked very detailed to me. Do not connect to a cooker circuit the man said.

After the disaster such as a fire, when you are in court gripping the bar, and explaining that you ignored the manufacturer's advice and guidance, as you knew better. You may well regret your decision. Will your insurance still be valid?

Z.

I give up. I have pointed out 10,000 times that all this is with assuming correct cables sizes & OCPDs. So for the 10,001th time - of course I would take the installation method into account. There is literally no point in me arguing any further if you're going to simply ignore every point I make. And you still haven't answered my eminently reasonable question about the 10mm2 SWA.

Bye.

That is not relevant, they still have a 5-10A supply.  How dies a 100A fuse change anything except stopping DNO callouts?

Just to put a spanner in the works ref diversity.

We used to allow 100 sq yards on a 30A ring final. 

Nowadays 100sq metres on a 32A ring final.

That`s an increase of about sixteen and a half percent then? How come?

Answers on a postcard

I cannot believe that this thread is still going.

The argument seems to be that the worst case scenario is that the protective device trips occasionally - assuming of course that the cable and OCPD are properly coordinated.

This then gets called "nuisance tripping", but IMHO there is no such thing. Either a device trips because an appliance is faulty, in which case it is doing the job for which it is intended; or due to bad design.

I also think that diversity is being mis-used here. 311.1 "... diversity may be taken into account." (my emphasis) So there is every possibility that the householder will take a shower whilst the oven is warming up, in which case the maximum demand is the sum of the two appliances. By contrast, if a house has a dozen sockets on a ring, it is most unlikely that large loads will be plugged into more than a couple outlets, let alone the whole lot.

If I were doing an EICR on this hypothetically over-loaded circuit, I would pay close attention to the terminals in the CU and junction boxes. Any sign of significant distress would be a C2, otherwise C3.

Oh no we didn't ! It was 30 amps per 1000 sq ft, while 100 sq yards is more like 900 sq feet.
I think however variation in ceiling height, room shape and internal layout and external house insulation and 101 other things cause consumption variations that utterly dwarf any error in metricating the area calculations. And do not forget we metricated the wire sizes too.

Mike

PS don't forget floor area served calculations for out door sockets ;-)

So, one day last year I got up early and drove around sixty miles to work and one of the jobs on the schedule is to connect the new 8.7 kW electric shower to the existing shower circuit. So I needed to assess the existing installation.

A single B40 MCB in a consumer unit in the garage without any RCD protection supplied a 6.0 mm twin and earth cable that ran along the garage wall to a 30 amp junction box from which a 6.00 mm twin and earth cable ran to the shower and another to the kitchen, where it supplies a freestanding cooker as well as a double socket over a worktop.

The choices were:

Option 1: just connect the shower to the existing circuit without altering the circuit or circuit protection.

Option 2: connect the to the existing circuit without altering it, but replace the MCB with a RCBO.

Option 3: Remove the shower circuit from the junction box and tidy up the cooker circuit, then install a new junction box to the shower circuit cable and extend it back to the consumer unit and connect it to a new RCBO, so the shower is completely separated from the cooker and socket circuit.

Are all options viable?

Which option would you go for?