Wiring In Kitchen Oven

[Arrods]

Thinking of installing a second oven in the re-design of our kitchen. Let me stress that we'll be getting a qualified electrician to do the work but just wanted a heads-up before we commence the re-design. I'm assuming the oven needs to be wired into the existing 'oven' cabling, albeit that the oven will be sited about 3 metres from the existing oven. (I know that there are ovens that come with a 13 amp plug, but let's assume the new one has to be wired in as I've described.) Any issues with my proposal?

One further point is that, the house was built in 1978 and doesn't have one of the new-fangled fuse/breaker boxes - just one switch to turn of the power with fuse wires for the individual circuits. Would it be a good idea to get that changed at the same time? Grateful for any advice.

[Togo]

If this oven is a single cavity electric oven, that cannot utilise the grill and main oven at the same time it is designed to run off the standard 13amp ring main. If it has a 13amp plug already fitted it does not require a 30 amp single supply cooker point or supply.

[Togo]

Now if the new oven is rated to be used on a supply above 13amps it will need it's own discreet supply and will not be able to be supplied from any existing 30amp cooker supply, as two double ovens would take the required supply above the 30amp limit. It can be furnished with a second 30 amp supply direct from your mains in supply and existing fuse box, but I think you may meet resistance(no pun intended) from a good electrician who would probably want to see an RCD unit in place. With any luck Sparkie or Builder will see your post and furnish a full tech spec for you. I would bump this thread later Arrods, when He and Builder are in from work. They are probably back in today.

[Arrods]

Thanks Togo. Just had a shufti at the additional 'new' oven and it looks as though it was originally wired into a 30 amp supply. Funnily enough, the previous oven to our existing one came with a 13 amp plug. It's just possible, from what you say in your first sentence that the existing can also be connected to the 13 amp system, in which case the additional one can utilise the 30 amp circuit.

Just shows you how important it is to check these things before embarking on what is likely to be a major project anyway and then finding all sorts of additional problems.

[Togo]

The main rule of thumb Arrods is, if it is a double oven (ie has a separate grill or double oven facility) it needs a separate 30 amp oven supply. If it is a single cavity oven with no ability to use grill and oven together, it is designed to run off the 13amp ring main. These ovens are supplied with a sealed 13amp plug already on them, the double ovens that require hard wiring to a discreet heavy oven supply do not. Most ovens will say on the plate with details on it what supply is required. It is of course possible that your "new" oven had the plug removed and was wired to an oven supply because that was the only supply near to hand. If it is single cavity it may well be OK to run it from your ring main. I would advise you to be absolutely sure that any supply, to these single cavity 13amp rated ovens, are indeed on the RING main and not a spur that someone has extended from the ring.

[donny48]

It is certainly a good idea to have a consumer unit fitted, safer and far more convenient in the event of an overload.

[Togo]

Hi Donny Happy New Year. You are right of course, but as you no doubt know that this usually escalates into a full house rewire. Been there.

[donny48]

Happy New Year to you to Togo, One tends to forget these escalations when you do this work yourself.
I do have a "tame" electrician to check my work and certificate.

[Togo]

Haha ditto, but it does help to have some knowledge beforehand. I am lucky in that my time in the electronics industry gave me the ability to foresee such events.

[donny48]

I was in maintenance working in two man teams of electrical and mechanical so could observe and learn, also was sent on some excellent courses.

[The Builder]

I think the others have told you what you need to know, Arrods. Naturally, it all depends on the total load.

From your second post, it seems as though one of the ovens can use the existing cooker circuit, and the other can be plugged into a ring circuit which, in the case of rewireable fuses, will be a 30A circuit.

Information plates (usually somewhere on the back of the oven) will give the load. Your electrician will soon be able to decide which is the best way.

As far as the consumer unit is concerned, there is no requirement for an upgrade unless, for some reason, the present arrangement is unsafe. It all costs money, but a modern CU is reccomended. It would be a good investment. Bear in mind though, that it would make sense for the entire system to be tested before upgrading.

Older rewireable systems can be quite tolerant of minor faults. A new CU with overall RCD protection (earth leakage trip) may well show up such faults. I've made this upgrade on several occasions without any problems, but you never can tell. All systems should be checked every 10 years. It would be in your interest to have this carried out.

In short - modern CUs have MCBs (miniature circuit breakers) in place of fuses. Much more convenient to reset. Your fuses may well be safely protecting the system from fire etc, but you have no RCD. Roughly speaking, MCBs protect the cables etc, while RCDs protect you.

The other "biggie" is your existing Earthing arrangement. Essential to have this checked too.

[Arrods]

My thanks to Togo, donny48 and The Builder for all of your comments. Will certainly bear in mind going forward. Happy new year to you all.