Cooker wiring

[Jaime]

We're thinking of getting a new range cooker (all electric). Currently theres a 30 amp (possibly 35 amp) cable into the kitchen and the 32 amp ring main. I know that for a seperate oven and hob usually the hob is wired to the cooker cable through an isolation switch and often the ovens to the ring main through a 16 amp plug or simular.

What happens with these large range cookers, I added the power comsumption on one and it came to a total of 67 A if all things where switched on. Would that need a new cable to the consumer unit or does it take power from both the cooker spur and the ring main? Also what happens in a normal house with single phase electrics, if your cooking a large lunch and some decides to have a shower with a 10kw shower (40 amps) thats goign to max out the 80 amp trip and the 100 amp consumer fuse. Presumable the trip just cuts the power on overload. Must cause a problem or are most modern houses that use electric for cooking 3 phase these days.

Its practically impossible to run a new cable back to the consumer unit, so I am wondering how this limits our choice of cooker.

Thanks

Jaime

[Lee Blaver]

Check out the instructions for the cooker, you may find that it has interlocks to prevent you from using all the features simultaneously.

Lee

[Jaime]

Thanks, any ideas how I find out the requirements of a cooker before we buy it.

Jaime

[Jaime]

snip

Yep 16kw, the one I used as an example has 5 rings on the top and 3 ovens/heaters. I didnt say this was needed, obversly if its there you have to make sure theres some failsafe in case soemone decides to switch it all one at once.

Yep agreed as its > 60 amps needs a 100 amp cable.

As I said its more than the 100 amp company fuse, however doens the rcd trip (80 amp) in a standard consumer unit have over load protection?

As I said this is the problem, what link in the chain prevents this. I fidn it odd as theres cookers are quite popular and so are electric showers so surely theres some kind of preventative feature in the chain.

Jaime

[The Natural Philosopher]

The point is, they never, ever, are.

The cable won't be 30Amp, probly nearer a 50A spur, and is normally fused at 45A from memory.

[The Natural Philosopher]

There is. Its called an MCB and it goes on the far end of the cable.

:-)

[Andrew McKay]

Just to be clear - the diversity calculations are different if the premises are non-domestic (e.g. a guest house, hotel or commercial premises).

I'm only pointing that out in case someone listens in to this thread and makes the wrong calculation.

Andrew

Do you need a handyman service? Check out our web site at

[Andrew McKay]

Actually it might be a 30A cable if diversity is applied.

Andrew

Do you need a handyman service? Check out our web site at

[impvan]

nd just to mop up another of your points, the RCD main trip does not have any overload protection; in your case this will be provided by the leccy board fuse. The main RCD looks for earth faults only.

[Jaime]

So in a 'normal' instalation with a 80 amp RCD and a 100 amp company fuse nothing stops the RCD being overloaded by up to 20 amps?

Jaime

[BigWallop]

No.

[harrogate]

Having come late into this thread, you would find it very hard to get anywhere like 80A drawn by most domestic cookers - in the old days of fuses they were usually never fed through anything higher than 60A!

It is all about statistical loading as most hotplates and the oven have thermostats. You would find it difficult to turn them all on at once, and by the time you turned the later ones on the earlier ones would have started to heat and the current drawn would have dropped.

[Jaime]

The 80 amp was anothe rpoint that I remarked, in that with a cooker and an electric shower or other high load device they could combined reach the 80 amp rating of a normal consumer RCD.

Jaime

[Terry]

Ee by goom! Just a mo? That don't sound right, some how? What's the point of buying all the bells and whistles if you can't use them. We've often had four boilers on the hobs on top, and stuff in the oven; for several hours at a time.

Let's see our common or garden, bog standard 30 inch North American stove has IIRC, 2 x 1250 hobs and 2 x 750 hobs and a 6 kilowatt oven, c'ept when it is first heating up the oven when the broiler eleemnt also comes on for a while. That's about 10 kilowatts, all on at same time. Roughly 40-45 amps. With a 60 amp plug and socket behind the cooker wired with #6 AWG to a dedicated 60 amp breaker back at the CU. Has worked fine for some

30+ years. Although our stove has been replaced with similar model during that time; twice.

Typical price these days for a new absolutely basic 30 inch cooker at moment is around $500 to $700 Can. Roughly say, with sales tax, 300 UK pounds. However fancier models, can go up to $1500; stainless steel for example even more! Competition between some of the 'big box' stores has been good and prices have actually come down during the last ten years or so. In typical domestic service (not including the way we have treated ours!) a typical unit will last 20 to 30 years. But no trouble for do it youselfers like myself to get a used one in good condition (and they are simple to fix) when people are remodeling!

Terry.

[Lee Blaver]

Some friends bought an all-electric range type cooker, with 5 "rings", a warming area, two ovens and a separate double grill. The way the controls are designed won't allow for all the items to be on at once.

The 5th ring won't operate if all the other 4 are on, and the "grill" can't be selected if both ovens are on.

This is a "domestic" model rather than a commercial one though, which is probably why. They have a large kitchen and admitted that they only bought it for the looks anyway, neither of them actually "cook" :-)

Lee

[usenet]

Anyone who actually cooks wouldn't buy a 'range cooker' anyway, none of the ones we looked at (or asked about) were really particularly good cookers. We bought 'separates' because it allowed us to get nearer to what we wanted at a rather lower price, though cost wasn't a particularly important factor.

[S Viemeister]

I have one of those Baby Bellings - it really confused my daughter-in-law - she thought it was broken.

[The Natural Philosopher]

You rate the MCB not on the cooker load, but on the grade of cable going to it. The purpose of the MCB is to prevent cables catching fire, so if its decent grade cooker cable 45A or 50A MCB is in order.

[The Natural Philosopher]

Migt be, but Ive never seen a cooker install done with standard T & E as per ring mains: Usually its a lot heavier than that.

[Jaime]

Yes I realise that, just didnt want it so that we got a cooker that kept tripping the mcb. Main problem is replacing the cable is not an option (too many rooms/walls).

Thanks

Jaime