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

Jaime wrote:


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.

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

Lee

--
To reply use lee.blaver and NTL world com

"Jaime" wrote in message
...
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



Bugger !!! Sorry, forgot to add this link as well:

http://www.tlc-direct.co.uk/Book/4.3.9.htm

"Lee Blaver" wrote in message
...
Jaime wrote:


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.

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


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

Jaime

snip

???? 67 amps ???? That means the range cooker has a total load of
16,080
Watts (16.08 Kw). How many heating rings are on top it ? What sizes are
the heating element in the ovens ? Are you sure you need ALL of the
cooker
ON just to make lunch ?

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.

http://www.cbcdesign.co.uk/cable.html

Depending on the length of the existing cable, you may have to up it to at
least 16 mm to take that kind of full load. Remembering that most
domestic
supplies are only 16 mm to begin with, then you may also have to have the
mains supply reinforced to take the load of your whole house with
everything
switched on at the same time.

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


With all elements heating on the stove and the shower running, that makes
a
total load of: 67 Amps + 42 Amps which equals 109 Amps, which in turn
makes
the 100 Amp supply fuse before the meter over heat and possibly burn out.

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?

This would mean your house would lose all of its supply and you'd have to
call out the electricity supplier to change their supply fuse, which will
let them see that you are drawing so much power from the supply that you
are
almost going into the category of being a small commercial premises, which
would then put you on to a higher business tariff for your supply. This
is
beginning to get very complicated.

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

snip
Bugger !!! Sorry, forgot to add this link as well:

http://www.tlc-direct.co.uk/Book/4.3.9.htm



Thanks for the link

Jaime

Jaime wrote:

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.


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.

Jaime wrote:

snip

???? 67 amps ???? That means the range cooker has a total load of

16,080

Watts (16.08 Kw). How many heating rings are on top it ? What sizes are
the heating element in the ovens ? Are you sure you need ALL of the

cooker

ON just to make lunch ?


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.



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


:-)

On Sat, 26 Jul 2003 21:39:16 +0100, "Jaime"
wrote:

The Regs allow you to apply diversity in a situation such as this, in
the specific case of a domestic electric cooker, you take the first 10A
of the total load, then add 30% of the remainder, plus another 5A if the
control unit contains a 13A socket. So, if the total load of the cooker
is 67A, then the circuit needs to be rated 10A + (0.3 * 57)A = 27.1A. so
a 32A MCB will be fine (at a pinch even if there is a socket in the
control unit) and in most normal circumstances 6mm^2 cable will also be
fine. The reason for this is that each heating element will have its own
thermostat, all of which will cycle 'out of sync' so the full load in
practice is unlikely to be drawn for anything other than a very short
time.

Thanks very much thats exactly the information I was looking for.

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 http://www.handymac.co.uk

On Sat, 26 Jul 2003 22:08:25 +0100, The Natural Philosopher
wrote:

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

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

Andrew

Do you need a handyman service? Check out our
web site at http://www.handymac.co.uk

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.

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.

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

"Jaime" wrote in message
...

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.

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



No.


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"BigWallop" wrote in message
...

"Jaime" wrote in message
...

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.

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



No.


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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.


--
Woody

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.


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

Lee Blaver wrote:

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

Lee

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.

Terry wrote:
Lee Blaver wrote:


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

Lee


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.

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

--
To reply use lee.blaver and NTL world com

Lee Blaver wrote:
Terry wrote:
Lee Blaver wrote:


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

Lee


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.

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" :-)

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.

--
Chris Green )

Owain wrote:

Baby Belling cookers came in two models, one for a 30A cooker point and one
for a 13A socket. The socket one had an interlock so everthing couldn't be
turned on simultaneously.

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

Jaime wrote:

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.


The Regs allow you to apply diversity in a situation such as this, in
the specific case of a domestic electric cooker, you take the first 10A
of the total load, then add 30% of the remainder, plus another 5A if the
control unit contains a 13A socket. So, if the total load of the cooker
is 67A, then the circuit needs to be rated 10A + (0.3 * 57)A = 27.1A. so
a 32A MCB will be fine (at a pinch even if there is a socket in the
control unit) and in most normal circumstances 6mm^2 cable will also be
fine. The reason for this is that each heating element will have its own
thermostat, all of which will cycle 'out of sync' so the full load in
practice is unlikely to be drawn for anything other than a very short
time.


Thanks very much thats exactly the information I was looking for.


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.



Regards

Jaime

Andrew McKay wrote:

On Sat, 26 Jul 2003 22:08:25 +0100, The Natural Philosopher
wrote:


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


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



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.


Andrew

Do you need a handyman service? Check out our
web site at http://www.handymac.co.uk

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.


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

80A RCD!!!! that isn;t going to be any good :-)

Did you mean an 80mA RCD,. or an RCD rated at 80A?

Yeh its a 30mA RCD rated for 80 A load.

Thanks

Jaime

Jaime wrote:

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.



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).


Exactly, so put te biggest MCB teh cabkle will stand, and vbuy eh cooker.

Trust me - and ohers - you will never ever have everything flat out. You
would die of heat exhaustion in the kitchen if you did :-)



Thanks

Jaime