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Old March 17th 19, 09:22 AM posted to uk.d-i-y
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Default New Induction Hob - CU Change Needed?

New kitchen planning underway. Looks like we're going to replace a gas hob with an induction hob requiring a 32A connection back to the CU (photo he https://goo.gl/CGJfg3)

The CU is pretty old (1995 when the house was built). There is a spare position but on the non-RCD protected side. I assume using this slot would not be acceptable practice?

I've noticed that the current cooker is also on the non protected side of the CU, and given there is a combined isolation switch/13A outlet next to the cooker I was wondering if regardless of the need to add the induction hob this alone should be a reason to update the CU, as that socket isn't protected by the RCD? Ignore the water heater note - the immersion heater is no longer connected.

A final question. Any reason not to use 10mm on the 10m run to the kitchen? Hob and oven won't be sharing a circuit.

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Old March 17th 19, 09:44 AM posted to uk.d-i-y
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Default New Induction Hob - CU Change Needed?

On Sun, 17 Mar 2019 02:22:09 -0700, Kevin H wrote:

New kitchen planning underway. Looks like we're going to replace a gas
hob with an induction hob requiring a 32A connection back to the CU
(photo he https://goo.gl/CGJfg3)

The CU is pretty old (1995 when the house was built). There is a spare
position but on the non-RCD protected side. I assume using this slot
would not be acceptable practice?


There are RCBOs available for that board. Probably secondhand, but they
are available.
You have one/two CB's there that arent a good fit, maybe look to get them
changed, they arent expensive.

I've noticed that the current cooker is also on the non protected side
of the CU, and given there is a combined isolation switch/13A outlet
next to the cooker I was wondering if regardless of the need to add the
induction hob this alone should be a reason to update the CU, as that
socket isn't protected by the RCD? Ignore the water heater note - the
immersion heater is no longer connected.


Like for like change, so you could use the existing arrangement. You need
to take into account the Manufacturers (of the hob) instructions, if they
call for a RCD, then it is prudent to fit one.

A final question. Any reason not to use 10mm on the 10m run to the
kitchen? Hob and oven won't be sharing a circuit.


No reason not to, but no reason to fit 10mm really, unless you are
expecting to upgrade to 50 amps or so in the future, or, it is run in
insulation.
4mm T&E may be enough, it can hold 37A clipped direct or buried in a
masonry wall.

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Old March 17th 19, 01:12 PM posted to uk.d-i-y
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Default New Induction Hob - CU Change Needed?

On 17/03/2019 09:22, Kevin H wrote:

New kitchen planning underway. Looks like we're going to replace a
gas hob with an induction hob requiring a 32A connection back to the
CU (photo he https://goo.gl/CGJfg3)

The CU is pretty old (1995 when the house was built). There is a


It may be old(ish) but its a decent brand and appears to be in good
order. (although that non Mem/Eaton water heater MCB does not fit that
well, and leaves a larger than desirable gap in the facia)

spare position but on the non-RCD protected side. I assume using this
slot would not be acceptable practice?


You appear to already have a cooker circuit there with a 32A MCB on it.
Any reason why you are not using that?

If you use that then its a like for like swap of appliance, and you
don't need to meet new requirements for cable protection.

If you want a completely new circuit, then looking to see if there is a
RCBO that will fit that CU might be a more pragmatic answer. (especially
with the space afforded by removing the water heater MCB - so even a
double module RCBO would be ok).

(Another option for more RCD space would be to get a longer bus bar for
the RCD side, and shorted the non RCD side, so you move the split to the
right a bit - but the RCBO would be a better choice IMHO).

I've noticed that the current cooker is also on the non protected
side of the CU,


With a single RCD "split load" installation like that, its quite common
to want the cooker on the non RCD side. Cookers (and anything else with
a mineral insulated heating elements in close proximity to moisture) are
a common source of higher earth leakage currents that are prone to
"sensitising" RCDs or even nuisance tripping them. Also there are not
many likely electric shock scenarios with a bit of fixed equipment like
a cooker.

and given there is a combined isolation switch/13A
outlet next to the cooker I was wondering if regardless of the need
to add the induction hob this alone should be a reason to update the
CU, as that socket isn't protected by the RCD?


Its a reason to get shot of the combined "cooker point". Since the
socket really would benefit from RCD protection, and it also reduces the
nominal capacity of the circuit by 5A [1]

[1] http://wiki.diyfaq.org.uk/index.php/Diversity

Ignore the water
heater note - the immersion heater is no longer connected.

A final question. Any reason not to use 10mm on the 10m run to the
kitchen? Hob and oven won't be sharing a circuit.


Nothing inherently wrong with it, although it would likely be overkill
unless you have many de-rating factors to contend with. 6mm^2 is more
commonly used, and has the benefit of being easier to work with.


--
Cheers,

John.

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Old March 17th 19, 01:19 PM posted to uk.d-i-y
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Default New Induction Hob - CU Change Needed?

On 17/03/2019 09:22, Kevin H wrote:
New kitchen planning underway. Looks like we're going to replace a gas hob with an induction hob requiring a 32A connection back to the CU (photo he https://goo.gl/CGJfg3)


I would say a good move. Easy to control and keep clean. Although I grew
up with a gas cooker I now find them quite alarming to use. There was
one running on Calor gas in a holiday home we quite often stayed at.

The four ring Bosch Induction hob I bought a couple of years ago has
three max current settings, 20A, 16A and 13A. The seller gave me £30
for the old hob, so the net cost was £300. I bought a similar Bosch hob
15 years ago. It cost me well over £400 and Mr Bosch had to come and
change the circuit boards after a couple of weeks.


--
Michael Chare
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Old March 17th 19, 06:12 PM posted to uk.d-i-y
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Default New Induction Hob - CU Change Needed?

On Sunday, 17 March 2019 13:12:36 UTC, John Rumm wrote:


You appear to already have a cooker circuit there with a 32A MCB on it.
Any reason why you are not using that?


We're keeping a built in cooker which is on the other side of the kitchen. I thought that and the hob would be asking too much. I've not checked to see what cable is used for the existing cooker. I'll check this and the rating for the cooker. That said today for example I was using two fan ovens and three gas rings when cooking sunday lunch.


If you want a completely new circuit, then looking to see if there is a
RCBO that will fit that CU might be a more pragmatic answer. (especially
with the space afforded by removing the water heater MCB - so even a
double module RCBO would be ok).

As Alan has pointed out, looks like MCBOs are still available, but at £30-40 each. Two of these would not be far off a new CU.


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Old March 17th 19, 07:17 PM posted to uk.d-i-y
ARW ARW is offline
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Default New Induction Hob - CU Change Needed?

On 17/03/2019 13:12, John Rumm wrote:
On 17/03/2019 09:22, Kevin H wrote:

New kitchen planning underway. Looks like we're going to replace a
gas hob with an induction hob requiring a 32A connection back to the
CU (photo he https://goo.gl/CGJfg3)

The CU is pretty old (1995 when the house was built). There is a


It may be old(ish) but its a decent brand and appears to be in good
order. (although that non Mem/Eaton water heater MCB does not fit that
well, and leaves a larger than desirable gap in the facia)

spare position but on the non-RCD protected side. I assume using this
slot would not be acceptable practice?


You appear to already have a cooker circuit there with a 32A MCB on it.
Any reason why you are not using that?

If you use that then its a like for like swap of appliance, and you
don't need to meet new requirements for cable protection.

If you want a completely new circuit, then looking to see if there is a
RCBO that will fit that CU might be a more pragmatic answer. (especially
with the space afforded by removing the water heater MCB - so even a
double module RCBO would be ok).

(Another option for more RCD space would be to get a longer bus bar for
the RCD side, and shorted the non RCD side, so you move the split to the
right a bit - but the RCBO would be a better choice IMHO).


Sorry John but that's not going to work on the Memera 2000.

They are a fixed bus bar CU and that is not a spare way next to the main
switch but a deliberate unusable blank..

A single module RCBO might work.

Cheers


--


Adam
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Old March 17th 19, 07:59 PM posted to uk.d-i-y
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Default New Induction Hob - CU Change Needed?

On 17/03/2019 19:17, ARW wrote:
On 17/03/2019 13:12, John Rumm wrote:
On 17/03/2019 09:22, Kevin H wrote:

New kitchen planning underway. Looks like we're going to replace a
gas hob with an induction hob requiring a 32A connection back to the
CU (photo he https://goo.gl/CGJfg3)

The CU is pretty old (1995 when the house was built). There is a


It may be old(ish) but its a decent brand and appears to be in good
order. (although that non Mem/Eaton water heater MCB does not fit that
well, and leaves a larger than desirable gap in the facia)

spare position but on the non-RCD protected side. I assume using this
slot would not be acceptable practice?


You appear to already have a cooker circuit there with a 32A MCB on
it. Any reason why you are not using that?

If you use that then its a like for like swap of appliance, and you
don't need to meet new requirements for cable protection.

If you want a completely new circuit, then looking to see if there is
a RCBO that will fit that CU might be a more pragmatic answer.
(especially with the space afforded by removing the water heater MCB -
so even a double module RCBO would be ok).

(Another option for more RCD space would be to get a longer bus bar
for the RCD side, and shorted the non RCD side, so you move the split
to the right a bit - but the RCBO would be a better choice IMHO).


Sorry John but that's not going to work on the Memera 2000.

They are a fixed bus bar CU and that is not a spare way next to the main
switch but a deliberate unusable blank..


ok that makes it harder :-)

Although one could replace the existing cooker and water heater MCBs to
get two free adjacent ways.

That could allow a single double width RCBO to be sized to satisfy the
diverse load of both cookers.

A single module RCBO might work.


I don't recall having those CUs open (at least not the plastic version),
how much height is there available inside?



--
Cheers,

John.

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\================================================= ================/
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Old March 17th 19, 08:53 PM posted to uk.d-i-y
ARW ARW is offline
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Default New Induction Hob - CU Change Needed?

On 17/03/2019 19:59, John Rumm wrote:

I don't recall having those CUs open (at least not the plastic version),
how much height is there available inside?



Bugger all.

Now if the OP was considering a DIY CU swap then why not do it now?

Metal clad dual RCD (or RCBOs if funds allow).




--
Adam
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Old March 17th 19, 10:17 PM posted to uk.d-i-y
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Default New Induction Hob - CU Change Needed?

On Sunday, 17 March 2019 20:54:00 UTC, ARW wrote:
On 17/03/2019 19:59, John Rumm wrote:

I don't recall having those CUs open (at least not the plastic version),
how much height is there available inside?



Bugger all.

Now if the OP was considering a DIY CU swap then why not do it now?

Metal clad dual RCD (or RCBOs if funds allow).




--
Adam


A new kitchen is looking like 8k (units, couple of appliances, plastering, lighting and flooring). Spending a couple of hundred upgrading the CU to be future proof for another 20 years would seem like a sensible investment.

Any recommendations for which CU to choose? Also, you can't do a job like this without buying some new kit. Would there be one thing that would make the CU swap easier for a mostly competent DIYer?
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Old March 18th 19, 01:52 AM posted to uk.d-i-y
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Default New Induction Hob - CU Change Needed?

On 17/03/2019 22:17, Kevin H wrote:
On Sunday, 17 March 2019 20:54:00 UTC, ARW wrote:
On 17/03/2019 19:59, John Rumm wrote:

I don't recall having those CUs open (at least not the plastic
version), how much height is there available inside?



Bugger all.

Now if the OP was considering a DIY CU swap then why not do it
now?

Metal clad dual RCD (or RCBOs if funds allow).




-- Adam


A new kitchen is looking like 8k (units, couple of appliances,
plastering, lighting and flooring). Spending a couple of hundred
upgrading the CU to be future proof for another 20 years would seem
like a sensible investment.

Any recommendations for which CU to choose? Also, you can't do a job
like this without buying some new kit. Would there be one thing that
would make the CU swap easier for a mostly competent DIYer?


What kind of test gear have you got?


--
Cheers,

John.

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


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