Built in oven connection options

missindie

Old oven was 3kw on a plug. Bought new oven 3.6kw. No idea they weren't all on plugs and of course it needs hardwiring. Problem is, fuse box is near front door and kitchen in the back of house. Can't afford for upstairs floors to come up in order to route cable (time consuming/expensive/messy job) as floor is fairly recent. The hob is on a different wall and hardwired into that wall and on a red switch plate on the same wall above the counter. There is a black round box at the back of the oven housing and two sockets. There is also a double socket wired into the lower oven housing cupboard. Is there any other way to connect oven safely? 

grumbler

missindie said:

Old oven was 3kw on a plug. Bought new oven 3.6kw. No idea they weren't all on plugs and of course it needs hardwiring.

Can you return or exchange it to a different one?

Problem is, fuse box is near front door and kitchen in the back of house. Can't afford for upstairs floors to come up in order to route cable (time consuming/expensive/messy job) as floor is fairly recent.

I think, theoretically you can run a cable outside in a plastic conduit.

There is a black round box at the back of the oven housing and two sockets. There is also a double socket wired into the lower oven housing cupboard. Is there any other way to connect oven safely?

Well, you have to find out how these sockets are connected to the CU. It can be a separate circuit  (radial? ring? MCB rating?) or they can belong to a bigger ring. What are other sockets of the ring used for? A ring is normally protected by  32A MCB i.e. can easily handle 3.6kW. A double socket can handle 2x10A (=4.8kW) IIRC. Not sure if a socket can be replaced with an unfused connection box. Most likely, not. Can it be a local 16A MCB instead?

I'm just improvising. More knowledgeable people will comment soon.

cerebus

Need to what circuit was the old oven connected to , what the size of the mcb is and what size cable is installed

There's a good chance you can simply wire the oven into the connection box at the back of your oven cupboard , we are only talking about an additional 600 watts so this should be fairly simple to solve

Pics however would be useful so I can see what you are talking about 

Double sockets can handle 26 amps by the way as they are 2 × 13amp sockets be a bit of a design flaw if they couldn't 

grumbler

cerebus said:

Double sockets can handle 26 amps by the way as they are 2 × 13amp sockets be a bit of a design flaw if they couldn't 

You can plug 2x13A and get away with this, but the rating is 20A.

missindie

Thanks everyone 😀. @cerebus I'll add some pics. I'm sorry all of the technical stuff literally is greek to me 🤣🤦🏼‍♀️. Old oven was 3kw. I also wonder what would have happened if I had kept the oven under the hob (where the old one was before kitchen refit)? How would they have both been wired in then?

cerebus

grumbler said:

cerebus said:

Double sockets can handle 26 amps by the way as they are 2 × 13amp sockets be a bit of a design flaw if they couldn't 

You can plug 2x13A and get away with this, but the rating is 20A.

Some manufacturers (mk is one) rate their sockets at 20amp but they can take 26 amps, again if they couldn't there would be a lot of fires up and down the country when people plug in a tumble dryer into the same socket as a washing machine  , which happens quite often 

cerebus

missindie said:

Thanks everyone 😀. @cerebus I'll add some pics. I'm sorry all of the technical stuff literally is greek to me 🤣🤦🏼‍♀️. Old oven was 3kw. I also wonder what would have happened if I had kept the oven under the hob (where the old one was before kitchen refit)? How would they have both been wired in then?

Great set of pics they help loads.

That 30amp brown Junction box you mentioned can be used to wire in your new oven , which makes it very simple to do.

If you fancy having a go yourself don't forget to sleeve the earth and make the connections nice and tight and do a tug test.oh and test for dead before you start

Just to confirm what circuit is the junction box connected to? House sockets or cooker?

As you seem to only have one rcd protecting all your cuircuits , you have to be careful if you just switch off the mcb protecting the circuit you're working on , this is because if you touch the neutral and earth together you will trip the rcd , you will not get a shock however 

As for the cooker and hob on the same circuit , this can be done on the 32amp mcb due to diversity even though the total load is around 10,000 watts not all that wattage will be on at the same time due to the thermostats cycling them on or off

I await with baited breathe everybody who tells me this can't be done because they don't understand diversity , it can 

grumbler

cerebus said:

grumbler said:

cerebus said:

Double sockets can handle 26 amps by the way as they are 2 × 13amp sockets be a bit of a design flaw if they couldn't 

You can plug 2x13A and get away with this, but the rating is 20A.

Some manufacturers (mk is one) rate their sockets at 20amp but they can take 26 amps, again if they couldn't there would be a lot of fires up and down the country when people plug in a tumble dryer into the same socket as a washing machine  , which happens quite often 

It's not only MK. I am yet to see a socket officially rated 26A by a manufacturer. AFAIK, the requirement is to test them up to 20A total, the official rating is even lower. The reason is a fuse in a plug heating both the plug and the socket. At high currents its temperature is close to the melting point.
That said, in practice you can get away with 2x13A. And when you hardwire an appliance there is no this problem because there is no fuse. The question is whether the oven cable can handle 32A as without a fuse the MCB is the only protection.

Section62

cerebus said:

missindie said:

Thanks everyone 😀. @cerebus I'll add some pics. I'm sorry all of the technical stuff literally is greek to me 🤣🤦🏼‍♀️. Old oven was 3kw. I also wonder what would have happened if I had kept the oven under the hob (where the old one was before kitchen refit)? How would they have both been wired in then?

Great set of pics they help loads.

That 30amp brown Junction box you mentioned can be used to wire in your new oven , which makes it very simple to do.

If you fancy having a go yourself don't forget to sleeve the earth and make the connections nice and tight and do a tug test.oh and test for dead before you start

Just to confirm what circuit is the junction box connected to? House sockets or cooker?

As you seem to only have one rcd protecting all your cuircuits , you have to be careful if you just switch off the mcb protecting the circuit you're working on , this is because if you touch the neutral and earth together you will trip the rcd , you will not get a shock however 

As for the cooker and hob on the same circuit , this can be done on the 32amp mcb due to diversity even though the total load is around 10,000 watts not all that wattage will be on at the same time due to the thermostats cycling them on or off

I await with baited breathe everybody who tells me this can't be done because they don't understand diversity , it can 

In this case diversity isn't really the main issue.

The OP shouldn't do what you are recklessly advising them to do, because the level of protection and capacity of that circuit is unclear. You are just guessing and making assumptions.

It is also dangerous advice to tell the OP "you will not get a shock however".  That again makes certain assumptions about how the existing wiring has been done.

If the brown round junction box is on a final ring circuit then the OP cannot simply connect the cooker directly to the junction box. Again, if you think it is only a question of 'diversity' then you really aren't qualified to give advice on electrical installation work.

missindie

@cerebus. Thanks very much. How do I determine which circuit the brown box is wired on please? Thanks 

Section62

missindie said:

cerebus. Thanks very much. How do I determine which circuit the brown box is wired on please? Thanks 

You really need to get a professional electrician to check the wiring and advise you what to do.

cerebus may be giving the impression they know what they are talking about, but their advice is unwise and potentially dangerous.