My existing electric range is rated at 8500 watts, although that does
not include anything plugged into the two power points on the stove
(e.g. a 2300 watt jug, not that I do that).
The power point on the wall and the plug are rated at 30 amps, and the
circuit breaker 32 amps.

I have a new cooktop rated at 6400 watts and a separate oven rated at
2900 watts.
Is it OK to plug the oven into the cooktop, and run a humungous cable
to the power point?

I will never use all the elements at the same time. If anyone does
that the circuit breaker will trip, just like it would have with the
old oven (but it never did).

An electrican has said that I will need a new power point for the
oven, even though the new and old arrangements use almost the same
maximum amount of power.

On Sep 19, 6:55 am, Matty F wrote:
My existing electric range is rated at 8500 watts, although that does
not include anything plugged into the two power points on the stove
(e.g. a 2300 watt jug, not that I do that).
The power point on the wall and the plug are rated at 30 amps, and the
circuit breaker 32 amps.

I have a new cooktop rated at 6400 watts and a separate oven rated at
2900 watts.
Is it OK to plug the oven into the cooktop, and run a humungous cable
to the power point?

I will never use all the elements at the same time. If anyone does
that the circuit breaker will trip, just like it would have with the
old oven (but it never did).

An electrican has said that I will need a new power point for the
oven, even though the new and old arrangements use almost the same
maximum amount of power.

mmm don't know your building regs & someone will be along shortly, but
you could start with googling "diversity cooker"

http://www.tlc-direct.co.uk/Book/6.5.2.htm

Jim K

On 19/09/2011 06:55, Matty F wrote:

My existing electric range is rated at 8500 watts, although that does
not include anything plugged into the two power points on the stove
(e.g. a 2300 watt jug, not that I do that).
The power point on the wall and the plug are rated at 30 amps, and the
circuit breaker 32 amps.

I have a new cooktop rated at 6400 watts and a separate oven rated at
2900 watts.
Is it OK to plug the oven into the cooktop, and run a humungous cable
to the power point?

I will never use all the elements at the same time. If anyone does
that the circuit breaker will trip, just like it would have with the
old oven (but it never did).

In reality its highly unlikely it would - even if you turned the whole
lot on at once. The thermostats would kick in and drop the load before
the circuit breaker had a chance to complain. (they take some time to
respond to overloads. See:

http://wiki.diyfaq.org.uk/images/d/d...e-MCBTypeB.png

A 32A breaker will let you have 45A almost indefinitely, and even 50A
for 1000 secs (over quarter of an hour).

An electrican has said that I will need a new power point for the
oven, even though the new and old arrangements use almost the same
maximum amount of power.

Not being intimately families with your wiring regs, I can only give
guidance based on what we would do here...

I had a glance at:

http://www.energysafety.govt.nz/uplo...8/ecp51v18.pdf

Which seems to suggest similar sized circuits are the norm, although the
connection methods differ and the terminology is a bit different.

We would not normally connect the cooktop (I presume what is we would
call a "Hob"[1]) via plug and socket, but would hard wire it to a
"cooker point"[2] (basically a termination box with a big red switch,
and facility to clamp the cord to the hob / cooker (sometimes with a
built in socket as well)).

Hobs here would not have any additional sockets on them.

Cookers in general are treated with a significant allowance for "diversity":

http://wiki.diyfaq.org.uk/index.php?title=Diversity

In other words a recognition of the fact that the typical pattern of use
combined with being thermostatically controlled, its is very difficult
to draw anything like the theoretical maximum current for anything but
very short durations. Since circuit breakers permit short term
overloads, and the cable is adequately specified, its permitted in a
domestic environment, to connect even quite substantial cooking
equipment with a maximum load of up to 15kW to a 32A circuit. The
patterns of use and the thermostats, typically mean that even a 6kW hob
will rarely draw more than 20A.

Hence we would compute the effective demand as 10A + 30% of the
remaining maximum load (+5A if a socket is provided on the cooker point).

So in your case 6400 + 2900 = 9300W or 40A

The diverse load being 10 + 30% of 30 = 19A - so the circuit is fine for
feeding both devices. The only question then remains how to connect
them. That bit I can't really answer, since practice there is different.
With smaller ovens here, they are often designed to plug into a normal
13A socket since their load is often in the 1800 to 2200W range. Yours
is 2900 which suggests a double oven perhaps. I would expect that you
need a suitable socket of flex connection unit for the oven and possibly
a second one for the cooktop depending on the terminal capacity.



[1] Typical electric hob in the UK:

http://www.tlc-direct.co.uk/Main_Ind...lec/index.html

[2] Cooker point:

http://www.tlc-direct.co.uk/Main_Ind...s_3/index.html




--
Cheers,

John.

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On Sep 19, 10:58 pm, John Rumm wrote:

The diverse load being 10 + 30% of 30 = 19A - so the circuit is fine for
feeding both devices. The only question then remains how to connect
them. That bit I can't really answer, since practice there is different.
With smaller ovens here, they are often designed to plug into a normal
13A socket since their load is often in the 1800 to 2200W range. Yours
is 2900 which suggests a double oven perhaps. I would expect that you
need a suitable socket of flex connection unit for the oven and possibly
a second one for the cooktop depending on the terminal capacity.

On the wall is a large socket and switch, and I have the large plug
and wire from the old stove. I was proposing that the large wire can
go to the cooktop. Since the new cooktop is directly over the oven
it's effectively one unit which could be wired together. I was
thinking it would be nice to be able to have a plug on the oven wire
in case the units have to be separated for maintenance, but maybe it
could be wired in permanently as that would be more reliable. And
cheaper too!

In my job I do deal with currents of several hundred amps, and in an
earlier job I designed and made transformers using up to 5000 amps.
But I'm not up with current house wiring idiocy ^B^B^B^B^B^B
regulations! (What is the command to denote Rub Out?)

On Sep 19, 10:58 pm, John Rumm wrote:

With smaller ovens here, they are often designed to plug into a normal
13A socket since their load is often in the 1800 to 2200W range. Yours
is 2900 which suggests a double oven perhaps. I would expect that you
need a suitable socket of flex connection unit for the oven and possibly
a second one for the cooktop depending on the terminal capacity.

I have been pursuaded to have an extra 15 amp socket installed in the
wall next to the 30 amp socket.

On 20/09/2011 08:57, Matty F wrote:
On Sep 19, 10:58 pm, John wrote:

With smaller ovens here, they are often designed to plug into a normal
13A socket since their load is often in the 1800 to 2200W range. Yours
is 2900 which suggests a double oven perhaps. I would expect that you
need a suitable socket of flex connection unit for the oven and possibly
a second one for the cooktop depending on the terminal capacity.

I have been pursuaded to have an extra 15 amp socket installed in the
wall next to the 30 amp socket.

Yup, extra socket would be fine by the sounds of it. I would not bother
with running an extra circuit for it though. i.e. I would have both
sockets on the same circuit.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Sep 20, 10:10 pm, John Rumm wrote:
On 20/09/2011 08:57, Matty F wrote:

On Sep 19, 10:58 pm, John wrote:

With smaller ovens here, they are often designed to plug into a normal
13A socket since their load is often in the 1800 to 2200W range. Yours
is 2900 which suggests a double oven perhaps. I would expect that you
need a suitable socket of flex connection unit for the oven and possibly
a second one for the cooktop depending on the terminal capacity.

I have been pursuaded to have an extra 15 amp socket installed in the
wall next to the 30 amp socket.

Yup, extra socket would be fine by the sounds of it. I would not bother
with running an extra circuit for it though. i.e. I would have both
sockets on the same circuit.

Yes, using the same switch. The switch is on the wall above the
cooktop. Cooks will assume that the switch operates on both the
cooktop and the oven, as it used to do.
A new problem is that the oven has a clock that needs to be reset
every time the power is turned off otherwise the oven won't go at all.

On 20/09/2011 11:19, Matty F wrote:
On Sep 20, 10:10 pm, John wrote:
On 20/09/2011 08:57, Matty F wrote:

On Sep 19, 10:58 pm, John wrote:

With smaller ovens here, they are often designed to plug into a normal
13A socket since their load is often in the 1800 to 2200W range. Yours
is 2900 which suggests a double oven perhaps. I would expect that you
need a suitable socket of flex connection unit for the oven and possibly
a second one for the cooktop depending on the terminal capacity.

I have been pursuaded to have an extra 15 amp socket installed in the
wall next to the 30 amp socket.

Yup, extra socket would be fine by the sounds of it. I would not bother
with running an extra circuit for it though. i.e. I would have both
sockets on the same circuit.

Yes, using the same switch. The switch is on the wall above the
cooktop. Cooks will assume that the switch operates on both the
cooktop and the oven, as it used to do.
A new problem is that the oven has a clock that needs to be reset
every time the power is turned off otherwise the oven won't go at all.

Is there any reason to actually turn it off? (the switch is really only
there for emergencies).

(in the UK it would also be suitable for isolation of the equipment
prior to servicing, but I note from your wiring code doc, the switch
only needs to be single pole - and so it not adequate for complete
isolation)


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In message
,
Matty F writes
But I'm not up with current house wiring idiocy ^B^B^B^B^B^B
regulations! (What is the command to denote Rub Out?)
^H (backspace)
http://en.wikipedia.org/wiki/ASCII
--
Nick (=----)

On Sep 22, 7:42 am, Nick wrote:
In message
,
Matty F writesBut I'm not up with current house wiring idiocy ^B^B^B^B^B^B
regulations! (What is the command to denote Rub Out?)

^H (backspace)http://en.wikipedia.org/wiki/ASCII

Thanks, I didn't know what to Google for. Obviously "Epanorthosis"
http://en.wikipedia.org/wiki/Epanorthosis

On Sep 20, 11:19*am, Matty F wrote:
On Sep 20, 10:10 pm, John Rumm wrote:



On 20/09/2011 08:57, Matty F wrote:

On Sep 19, 10:58 pm, John *wrote:

With smaller ovens here, they are often designed to plug into a normal
13A socket since their load is often in the 1800 to 2200W range. *Yours
is 2900 which suggests a double oven perhaps. I would expect that you
need a suitable socket of flex connection unit for the oven and possibly
a second one for the cooktop depending on the terminal capacity.

I have been pursuaded to have an extra 15 amp socket installed in the
wall next to the 30 amp socket.

Yup, extra socket would be fine by the sounds of it. I would not bother
with running an extra circuit for it though. i.e. I would have both
sockets on the same circuit.

Yes, using the same switch. The switch is on the wall above the
cooktop. Cooks will assume that the switch operates on both the
cooktop and the oven, as it used to do.
A new problem is that the oven has a clock that needs to be reset
every time the power is turned off otherwise the oven won't go at all.

Perhaps you could obtain from your work a knife switch, a slate board
for dual pole fusing, and a wooden connector block.


NT