Two ovens on one circuit – electrician installed only one circuit

Hello everyone,

I need your assessment on something that honestly left me speechless.

During the construction of our house, the electrical installation was carried out by the builder’s electrician. The oven socket had initially simply been forgotten and had to be redone anyway. In the conversation back then, I clearly stated that we plan to have two ovens instead of one – a regular oven with microwave function and a steam oven – and that these logically each need to be separately fused.

Now that the kitchen is completely installed (including granite countertop, everything finished), I operated both devices simultaneously for the first time and immediately the circuit breaker tripped. Looking in the fuse box, I see that there is only one fuse labeled “oven,” so both sockets are apparently on the same circuit.

Yes, I know, I should have noticed this earlier, but unfortunately I did not.

From all the research I have done in the meantime (VDE 0100-430 and 0100-520), this is definitely not permissible, as the combined load of the two devices significantly exceeds the allowed continuous load for a 16-A circuit. Can anyone knowledgeable confirm this?

Overload protection	Circuit must not be overloaded by two ovens	VDE 0100-430 (433.1)
Dimensioning	Circuit must correspond to operating current	VDE 0100-520 (523.1)
Separate circuits	Each high-power consumer its own circuit	DIN 18015-1 (10.1)
Compliance	Violation of VDE = Violation of EnWG § 49 Abs. 2	EnWG

Now I am wondering whether the fault clearly lies with the electrician here and whether he must rectify it at his own expense. I am also interested in who bears the costs in such a case if parts of the kitchen have to be dismantled again during refurbishment. And finally: What is the best way to approach this so that the situation does not immediately escalate into a dispute?

I want to clarify this with the electrician as calmly and objectively as possible, but honestly I find it quite incomprehensible – especially since the circuit had to be installed afterwards anyway and it was clear that two high-power consumers would be connected here.

I am looking forward to your opinions and experiences.

Best regards
dergert

Hello,

that an oven should have its own fuse is undisputed. But this here:

In the conversation back then, I clearly said that we plan two ovens instead of one – a regular oven with microwave function and a steam oven – and that these obviously each need to be fused separately.

could become a problem. You said it – do you have any proof of that? Witnesses? If the craftsman now says "I didn’t know about two ovens," it will be difficult.

It doesn’t help you now, but something like that must ALWAYS be done in writing... Alone to prevent anything from simply being forgotten.

Another, and probably even bigger problem – what does the contract say? If it only mentions one oven socket and you haven’t commissioned a second one as an extra from the developer, the ground could get very thin for you. In other words, if you didn’t order it, why should the electrician provide it?

Good luck and best regards,
Andreas

Hello,

is the fuse a single or a triple fuse? And what value, B16? And which devices are involved (connected single-phase/ two-phase or three-phase, what is the maximum power each)?
Is there a hob nearby, and how is it connected and protected? Some hobs only need two phases, then you might be able to repurpose the third for an oven.
And does the fuse blow immediately when both are on (without heating), or only when both are heating simultaneously?

It doesn't help you now, but something like that must ALWAYS be done in writing.... If only to prevent something from simply being forgotten.

Hello Andreas, yes of course, I have that in writing. After the oral discussion, I sent a plan in which it is unequivocally clear that two ovens are planned there.

Another, and probably even bigger problem - what does the contract say? If it only mentions one oven socket and you didn’t commission a second one as a special feature from the developer, the ground might be very shaky for you. In other words, if you didn't order it, why should the electrician supply it?

This subsequently supplied socket was paid for by the developer. The other one I personally commissioned from the electrician as an additional request. So that should already be correct. Everything was documented and is also stated that way on the paid invoice. It says "Additional socket 2-fold (separately fused) oven". As a layman, I understand from that that my wishes were taken into account. In hindsight, it should of course say ovens, but I didn’t notice that back then, or even question it at all. I mean, they even reopened the wall again because of the oven cable. I would never have thought that they would then just lay one cable instead of two.... why should they? They definitely knew that two ovens were going to be installed there.

Is the fuse a single or a triple fuse? And what rating, B16?

Single, B16.

And what devices are they (single-phase / two-phase or three-phase connected, maximum power respectively)?

I think single-phase, but to be honest I’m not sure.

[*]Bosch HMG978NB1 about 3.6 kW
[*]Bosch CSG958DB1 about 3.3 kW

Is there a hob nearby, and how is it connected and fused?

The hob is located in the kitchen island with its own line directly below going to the cellar -> fuse box.

And does the fuse trip immediately when both are on (without heating), or only when both are heating simultaneously?

No, only when both are heating simultaneously, after about 5 minutes it tripped. That’s why I only noticed it today, because this case hadn’t happened before.

Can you say anything about how this looks legally? Is this way of putting two ovens on the same line considered sloppy work and do I have any leverage to request remedial work? In other words, if it is clear that two ovens will be installed, must the electrician not ensure a separately fused circuit for each according to the current state of the art?

Take a look at the electrical plan to see how the sockets are labeled. If both say "oven," then you can refer to the fact that it was not executed properly. Practically: Do you have more sockets in the row? Are the refrigerator, sockets for appliances, and dishwasher also running on the same circuit breaker? If not, you can put the fridge on the circuit breaker of one oven and connect the other oven to the fridge's socket. It’s not ideal, but it might solve a practically relevant part of the problem.

Talk to the electrician, maybe he has an idea how to solve this easily. Everything else is just guesswork. The electrician (hopefully still) knows which cables he pulled where, maybe there are even 2 cables there or it’s a 5x2.5 which for some reason wasn’t connected correctly, etc. Often it’s different people, one pulls the cables and weeks later someone else connects everything. You can’t think as stupidly as it’s sometimes done on construction sites...

The fact is in any case that a solution like described above, that is simply connecting the stove with another device to one socket, is NOT permissible. It gets interesting if something ever happens. Insurances love such botched jobs to have an excuse not to pay if the house burns down.

PS: The idea that you get a completely new cable and he covers all resulting costs... I would discard that immediately. I also think a court would consider the effort disproportionately high in such a case and seek some compromise.