Oven connection

hughowen · 22-06-2020 7:20pm #1

Hi there, I recently bought a new Smeg single oven and I have existing 6mm² cable connected to 32amp fuse ready to connect this.
To my astonishment the oven has a 1.5mm cable at the back and fitting instructions say connect to a plug and a breaker.
I put a plug on and it works perfectly, question is is it safe to use the existing 6cm cable and breaker and just join the cable in a junction box effectively joining the 1.5cm and the 6mm in a box after the breaker
Regards
Owen

22-06-2020 8:02pm

I would connect the 6 sq. to a spur outlet. This would allow me to fuse down to 13A and connect feed the oven to the output of the spur outlet. This would mean that the oven cable will be protected. A 32A fuse will not provide protection to a cable that small. It would also mean that no work needs to be done on the fuse board (although it may need attention if it still uses fuses for cooler circuits).

hughowen · 22-06-2020 9:36pm

Thanks for reply, so if I'm reading you right I can connect the 6mm to a regular "spare" socket, which I can install separately and plug my oven into that. I'll still have the breaker to cut off supply if needed. I can change the 32amp in the fuse board if that is better, or recommended,
I plugged the oven in to a regular socket and it worked perfectly so it's just making sure it's not dangerous to use 6mm, I can change if it is better use 2.5mm straight from the fuse box and use 16amp fuse or whatever I need
Thanks again

2011 wrote: »

I would connect the 6 sq. to a spur outlet. This would allow me to fuse down to 13A and connect feed the oven to the output of the spur outlet. This would mean that the oven cable will be protected. A 32A fuse will not provide protection to a cable that small. It would also mean that no work needs to be done on the fuse board (although it may need attention if it still uses fuses for cooler circuits).

meercat · 22-06-2020 9:47pm

This is what 2011 is referring to( do not connect the oven into a socket outlet)

https://www.screwfix.ie/p/mk-logic-plus-13a-switched-fused-spur-flex-outlet-white-with-colour-matched-inserts/13479

hughowen · 22-06-2020 10:06pm

Okay, I need to change the breaker I have which is 45amp to a 13amp using the 6mm already there and then run to a separate socket dedicated to the oven. I can if needed change the whole run to 2.5mm if that is safer or more recommended
quote="meercat;113815052"]This is what 2011 is referring to( do not connect the oven into a socket outlet)

https://www.screwfix.ie/p/mk-logic-plus-13a-switched-fused-spur-flex-outlet-white-with-colour-matched-inserts/13479[/quote]

Class MayDresser · 22-06-2020 10:10pm

No need to change the wiring, just put a 13A fused switch before the cooker. Is it stranded or solid?

hughowen · 22-06-2020 10:20pm

Class MayDresser wrote: »

No need to change the wiring, just put a 13A fused switch before the cooker. Is it stranded or solid?

So change the breaker to a 13amp from the 45 amp leave the 32amp on fuse board, the 6mm is stranded, the cooker cable is stranded, the 2.5mm is solid, connect the cable 2.5mm from the beaker to a socket and plug in the cooker to that, if I'm getting this right

Class MayDresser · 22-06-2020 10:41pm

hughowen wrote: »

So change the breaker to a 13amp from the 45 amp leave the 32amp on fuse board, the 6mm is stranded, the cooker cable is stranded, the 2.5mm is solid, connect the cable 2.5mm from the beaker to a socket and plug in the cooker to that, if I'm getting this right

I'm confused now. Where are you getting the 45A breaker from?
Why have you still got the idea of using a plug top and socket in your head?
Would you be better off letting a RECi install it?

hughowen · 22-06-2020 10:49pm

Class MayDresser wrote: »

I'm confused now. Where are you getting the 45A breaker from?
Why have you still got the idea of using a plug top and socket in your head?
Would you be better off letting a RECi install it?

The 45amp breaker is already there, I have to go from that to the oven which is the 1.5mm to be used with a plug, i can change the run from the breaker to connect anyway possible to the oven, it's just what size to come out of the breaker to connect to the oven cable be it a plug in or a junction box, if your Reci and available I'm in east cork, if not I tried to get somebody a few times but they were not interested in a small job. Sorry if I'm being a bit amateur but my level is domestic home use

22-06-2020 10:58pm

hughowen wrote: »

The 45amp breaker is already there, I have to go from that to the oven which is the 1.5mm to be used with a plug, i can change the run from the breaker to connect anyway possible to the oven, it's just what size to come out of the breaker to connect to the oven cable be it a plug in or a junction box, if your Reci and available I'm in east cork, if not I tried to get somebody a few times but they were not interested in a small job. Sorry if I'm being a bit amateur but my level is domestic home use

I really don’t want you to get hurt. Please get a professional in to do this. It shouldn’t cost much.

23-06-2020 10:49am

meercat wrote: »

( do not connect the oven into a socket outlet)

If you wanted to you could.
Hence the OP said
"To my astonishment the oven has a 1.5mm cable (prob a 2.5mm) at the back and fitting instructions say connect to a plug and a breaker."

Its electric hobs that draw big current!

Class MayDresser · 23-06-2020 11:07am

Wasn't there some new regulations brought in where all new self standing appliances have to be fitted using an isolating switch where possible?

hughowen · 23-06-2020 11:28am

Class MayDresser wrote: »

Wasn't there some new regulations brought in where all new self standing appliances have to be fitted using an isolating switch where possible?

Isolating switch is already there fitted with 6mm, but its 45amp, my question is should I run 2.5mm from that or change the 45amp to a 13 amp and run the rest with 2.5mm

23-06-2020 11:40am

Dont go digging around in the consumer unit.
If you don't know what to do get someone in.
2011s post tells you exactly what do and you still can't figure it out!

hughowen · 23-06-2020 11:52am

BrownFinger wrote: »

Dont go digging around in the consumer unit.
If you don't know what to do get someone in.
2011s post tells you exactly what do and you still can't figure it out!

Not going at the fuse box, the fitting is there already but was for a bigger oven

aido79 · 23-06-2020 12:07pm

hughowen wrote: »

Isolating switch is already there fitted with 6mm, but its 45amp, my question is should I run 2.5mm from that or change the 45amp to a 13 amp and run the rest with 2.5mm

Are you calling the cooker switch a 45 amp breaker? If so you really need to get an electrician involved in this.

sinnbox · 23-06-2020 12:16pm

hughowen wrote: »

Not going at the fuse box, the fitting is there already but was for a bigger oven

would you please take some photos

Flickerfusion · 23-06-2020 12:25pm

I’ve never quite understood the logic of the Irish (and British) regulations for this.

Modular cooking appliances should be on appropriately rated radial circuits, as they would tend to be on the continent.

We seem to have some hangover to the days of a big 1970s style slot-in double oven, grill and hob “cooker” that drew huge loads, even though most are now separate modules that draw <20A

A lot of single ovens are only 16Amp and designed to be plugged in to a Schuko socket on the continent.

It just surprises me as the regulations here are a are paranoid about fuse protecting flexes in every other context - fused plugs, fused spurs etc

Then you’ll find a combination oven, a hob and an oven all wired to a 32 or 45A “cooker” circuit without any protection for their individual flexes, which certainly aren’t rated 32A or 45A.

I know in my kitchen for example the oven and combination oven are on a 32A RCBO and the hob is on a second one. In reality, the combination oven and oven should be on 16 and 20amp MCBs and the hob hooked up separately to cope with 11kW max draw. (When turned onto induction boost on two zones it can draw that much)

You would really think we would have developed appropriate fused spurs eg 16 & 20Amp and even plug and socket connectors for these to allow easier, safer installation and maintenance.

It just surprises me as a lot of modern ovens, especially single ovens, are provided with a flex and probably should be provided with over current protection at much lower ratings.

sinnbox · 23-06-2020 12:42pm

Flickerfusion wrote: »

I’ve never quite understood the logic of the Irish (and British) regulations for this.

Modular cooking appliances should be on appropriately rated radial circuits, as they would tend to be on the continent.

We seem to have some hangover to the days of a big 1970s style slot-in double oven, grill and hob “cooker” that drew huge loads, even though most are now separate modules that draw <20A

A lot of single ovens are only 16Amp and designed to be plugged in to a Schuko socket on the continent.

It just surprises me as the regulations here are a are paranoid about fuse protecting flexes in every other context - fused plugs, fused spurs etc

Then you’ll find a combination oven, a hob and an oven all wired to a 32 or 45A “cooker” circuit without any protection for their individual flexes, which certainly aren’t rated 32A or 45A.

I know in my kitchen for example the oven and combination oven are on a 32A RCBO and the hob is on a second one. In reality, the combination oven and oven should be on 16 and 20amp MCBs and the hob hooked up separately to cope with 11kW max draw. (When turned onto induction boost on two zones it can draw that much)

You would really think we would have developed appropriate fused spurs eg 16 & 20Amp and even plug and socket connectors for these to allow easier, safer installation and maintenance.

It just surprises me as a lot of modern ovens, especially single ovens, are provided with a flex and probably should be provided with over current protection at much lower ratings.

does 4mm twin and earth exist in Ireland, icant remember where i read or heard that 6mm is unnecessary for most if not all combination cooker installs and that 4mm was more appropriate or acceptable

hughowen · 23-06-2020 12:47pm

aido79 wrote: »

Are you calling the cooker switch a 45 amp breaker? If so you really need to get an electrician involved in this.

The photo is of the 45amp switch, with 6mm cable running to it from the fusebox if it is simply the case of changing that to a 13amp and run 2.5mm from it to the oven. then no probem other than that the fuse box has 32amp protecting that 6mm

meercat · 23-06-2020 1:01pm

BrownFinger wrote: »

If you wanted to you could.
Hence the OP said
"To my astonishment the oven has a 1.5mm cable (prob a 2.5mm) at the back and fitting instructions say connect to a plug and a breaker."

Its electric hobs that draw big current!

My reference was to the ops reply to 2011s answer

Not to fit a socket to the cooker tails

I wouldn’t advise connecting this load onto a socket circuit

Flickerfusion · 23-06-2020 1:03pm

sinnbox wrote: »

does 4mm twin and earth exist in Ireland, icant remember where i read or heard that 6mm is unnecessary for most if not all combination cooker installs and that 4mm was more appropriate or acceptable

The size of the conductors is appropriate if the MCB (circuit breaker) protecting them is rated appropriately to what they're capable of carrying. What concerns me is that a lot of cooking appliances come with prewired flexes and these may expect overcurrent protection at typically 20amps or so.

The NSAI really needs to look at this stuff as it's something that should be brought into line with something more in line with continental European norms, as those are the standards that those kinds of appliances are built to.

I prefer the use of local isolating switches here though, but I think we are all over the place on how we are wiring cooking appliances.

I don't really see how combining multiple appliances and connecting them, without adequate individual overcurrent protection, to one large breaker makes any sense.

I mean you wouldn't connect a dishwasher and a hob to a 32 or 45amp circuit, so why connect a 16 amp oven and a hob to a 32 or 45amp circuit?

OP: You should get an electrical contractor to do what you're describing. There are fire risks and no offence in any way attended, but you sound out of your depth on this one.

Making a mistake on this, including using poor technique to connect wires that are carrying sustained high loads and can result in fire risks and you are not talking about big money to get this done right.

aido79 · 23-06-2020 1:08pm

hughowen wrote: »

The photo is of the 45amp switch, with 6mm cable running to it from the fusebox if it is simply the case of changing that to a 13amp and run 2.5mm from it to the oven. then no probem other than that the fuse box has 32amp protecting that 6mm

That is a cooker switch not a breaker. Changing it to a 13 amp switch does not do anything to protect your oven and is pointless. You will still be relying on the 32 amp breaker at the board for protection.
What has been suggested is that you leave the cooker switch and the fuseboard alone and add in a 13 amp spur between the cooker switch and the oven. There is no point in changing the 6mm cable from the cooker switch if the cable can be fitted off into the spur at the input. Then you just need to connect the oven to the output of the spur. That way the cable and the oven are protected by a 13 amp fuse and not the 32 amp breaker at the board.

hughowen · 23-06-2020 1:23pm

aido79 wrote: »

That is a cooker switch not a breaker. Changing it to a 13 amp switch does not do anything to protect your oven and is pointless. You will still be relying on the 32 amp breaker at the board for protection.
What has been suggested is that you leave the cooker switch and the fuseboard alone and add in a 13 amp spur between the cooker switch and the oven. There is no point in changing the 6mm cable from the cooker switch if the cable can be fitted off into the spur at the input. Then you just need to connect the oven to the output of the spur. That way the cable and the oven are protected by a 13 amp fuse and not the 32 amp breaker at the board.

Thanks for all the help, above is exactly what I am doing, I'm putting a spur to to the oven at 13amp and connecting the oven to the spur.
Sorry if any confusion from mis-calling names of breaker and switch
Thanks everyone

aido79 · 23-06-2020 1:27pm

hughowen wrote: »

Thanks for all the help, above is exactly what I am doing, I'm putting a spur to to the oven at 13amp and connecting the oven to the spur.
Sorry if any confusion from mis-calling names of breaker and switch
Thanks everyone

Just to clarify. Are you leaving the 45 amp cooker switch as it is?

hughowen · 23-06-2020 2:01pm

aido79 wrote: »

Just to clarify. Are you leaving the 45 amp cooker switch as it is?

Yes, except to change the exit cable to 2.5mm and connect that to a 13amp cooker switch

23-06-2020 2:05pm

the mind boggles

23-06-2020 2:08pm

meercat wrote: »

My reference was to the ops reply to 2011s answer

Not to fit a socket to the cooker tails

I wouldn’t advise connecting this load onto a socket circuit

again you can put a oven on a 13amp plugtop and plug it into any socket without problem.
They only draw a kilowatt or so .

Flickerfusion · 23-06-2020 2:37pm

BrownFinger wrote: »

again you can put a oven on a 13amp plugtop and plug it into any socket without problem.
They only draw a kilowatt or so .

It depends on the oven. You can’t generalise.
Many single ovens are rated around 3.2 to 3.5kW, which is well beyond the capability of an Irish 13 amp plug and they would also blow the fuse on a 13amp spur.

Just because the instructions may say they should be plugged in on the continent does not mean that's possible in Ireland as the plug/socket system is substantially different.

They might work on a continental Schuko plug, which would be on a dedicated radial circuit on the continent in this kind of use. They are rated 16amps and have fewer overheating risks - no fuse holder in the plug and the recessed design protects fingers from contact with the pins, without reducing the contact area. Irish / British plugs have quite a small area that actually makes contact in the upper area of the pin only. This is necessary to protect accidental finger contact, particularly in the days before they mandated plastic pin sheaths on part of the pin, so the plug only makes contact when almost fully inserted. A 16 amp schuko plug has bare pins and they make contact along a lot of their surface area.

So basically, you usually cannot connect then with a plug here using normal 3 pin plugs.

The maximum safe load for an Irish plug (particularly with a sustained load) is only about 2800W. If you calculate 13 amps x 230V = 2990 Watts, and considering that supplies here are more likely to be centred around the historical 220V range, as we originally standardised on the German/continental volage, it means you can pull about 2860W through an Irish wall socket.

(They historically used 240Volts in the UK so you can draw closer to 3000W usually if those plugs are used at British voltage. CENELEC (European standards agency for all things electrical - with scope & membership well beyond the EU) basically just split the difference and calls 220 to 240V range “230V” so you’ll still find higher voltage in the U.K. based on 240V centre and 220V everywhere else in Europe, including Ireland).

Generally speaking, plugged in appliances are only drawing a peak load for a short time - kettles, irons, washing machines etc don’t pull full load all the time or are used for short times. An oven can be drawing full load for long periods of time.

Anyway, to cut a long story short:

Read the rating plate on the oven. If it’s more than 2800W it should be hardwired to an appropriate fixed circuit, isolating switch and MCB (breaker) rated to protect the wiring on the circuit.

Connecting a heavy, resistive load like an oven to a plug and socket here is just asking for a fire, or certainly a melted/scorched socket & plug anyway.

The only suitable plugs here would be the industrial type and that’s really not a very suitable setup in a house.

OO7FITZY · 30-03-2023 4:14pm

hope someone can guide me on this as I haven't a clue TBH but have done some research so this is what I think:

situation is I have a double electric oven (rated max output 5.3kw), hooked up to a cooker switch linked to fuse board listed as 32amp

I want to swap out my gas hob for an induction hob but I see most of these have a rating output of 7.5kw-11kw depending on which model you get / if they have a boost function or not and how many rings in use

I assume I cannot connect both induction hob and oven to single 32amp connection as one of the calculators online said 7kw is the max power I can draw on so will I need an electrician to run a new 32amp cable to the fuse board or can the cable / fuse board but upgraded?

I don't want to have to try and chase a new cable and add a new switch etc unless I have to...but everything I read seems to lean that way :(

Also I don't want a plug in hob as you can really only run one ring on max as they are limited to 13amp plug

kirk. · 31-03-2023 5:16pm

I would hazard a guess another cable needed

I'd probably allow for worst case scenario christmas dinner

OO7FITZY · 03-04-2023 9:00am

Thx Kirk

I had a look behind the kitchen cabinet under the gas hob and there is a standard wall socket

can this be utilised/upgraded to service an induction hob?

kirk. · 04-04-2023 1:08pm

https://www.boards.ie/discussion/comment/120433904#Comment_120433904

No. Socket wouldn't do for that

I'm not sure on one 6sq doing both double oven and induction hob, I would just add separate cable anyhow

OO7FITZY · 04-04-2023 4:26pm

agree, prob safest option

only prob is chasing the new cable - not sure I can piggyback on the existing socket and want to avoid as much disruptions as possible

monseiur · 05-04-2023 12:50pm

https://www.boards.ie/discussion/comment/120433904#Comment_120433904

If your house is a bungalow or you have access to attic space directly above cooker location a handy electrician may be able to replace the cable from fuse board to existing standard socket at cooker with a suitably sized cable to suit induction hob - it would save the disruption & mess chasing walls etc will create.

Cerco · 05-04-2023 1:30pm

https://www.boards.ie/discussion/comment/120433904#Comment_120433904

Does your gas hob need a socket for ignition?

OO7FITZY · 06-04-2023 2:37pm

yes, the socket under my gas hob behind the kitchen cabinet is used for the sparker ignition

it's a solid brick wall so not sure you could chase an upgraded cable back to the fuse box

Oven connection

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