3 phase in the house

[Dusan]

We are rebuilding the house and there is now new 3 phase electrical installation. The final thing to be finished is 3 phase socket for kitchen stove. I have a stove that can be connected at 220v, 2x220v, 380V. I was expecting that the socket will be full 3 phase. However, the company installed 2x220V (going from the same phase, they call this double group) and they keep telling me that it is how they do in Holland, and that I cannot benefit from having 3phase socket.

My question is: shall I insist on having 3 phase socket and connect the stove as per the 3phase connection diagramme on the stove, or it s indeed without significant influence?

I can uderstand that such 2x220v makes sense on a single phase installation but why should this be an option when there is a 3 phase sysyem?

Another question, they tell me that 3 phase is bad because it uses only one null lead, which is then 3 times thinner than sum of 3 phase wires - are they talking nonsense? There are 3 null leads that come from the main board - will the wiring for that 3 phase be improved if all 3 null leas are connected to the 3 phase socket? Is that allowed? (I understand null is the same for all electrical consumers?)

Thaks for your replies in advance.

 

[mechelec]

Not sure of the setup or regs in the Netherlands. As this is a UK based forum you may get more answers from a forum based closer to home. What do the manufacturers of the stove recommend or is it them who are carrying out the install ?

 

[Dusan]

Not sure of the setup or regs in the Netherlands. As this is a UK based forum you may get more answers from a forum based closer to home. What do the manufacturers of the stove recommend or is it them who are carrying out the install ?

Well, the stove allows all types of connection. I have not contacted manufacturer as I am in the phase of closing the floor in the kitchen, and connecting the wires for the new 3phase wall socket before that (wires are brought to the kitchen below the floor). And I tried with Dutch electricians, but as I said, the answers are strange and not persuasive.

I think 3 phase socket increases the value of kitchen, as it always can be used as single or two phase.

I somehow think it is logical to use 3 phase connection if it exists, because more wires > less load to the installation/more load to the stove and/or better performance in demanding situations?

I see that fake 2 phase connection (2x220V on one phase i.e 2 16A fuses are used) which they call double group is an effort to provide more load on one phase through distribution of power on 2 wires, so the 16A fuses will survive, while when the same stove is connected to single phase 220V it cannot be loaded that much at one time (it limits itself through internal wiring), so the user suffers in speed (and my mother in law, who knows everything, says that it is then "weak power" and "oven does not work well". I must say it makes sense to me, there must be certain fall of voltage when too many consumers are used a the same time, so instead of 220, they will work on less votage, while if there are 3 phases it has to be a better situation? Or this is nonsense?

Why in our undeveloped country from where we came here to the developed West (one of the Balkan countries of former Yugoslavia), every apartment always had 3 phase in the kitchen?

I have checked, it is fairly uncommon for a household to have a 3 phase electrical installation in Holland. I don't know how is it in UK, but that is not in he essence of my question.

 

[Marvo]

Usually with an appliance like a stove which has multiple wiring options it wouldn't make a difference to its power consumption if it was wired on one larger single phase supply or on a 3 phase supply. All the heating elements are usually 230v and they'll have this voltage supplied with both wiring schemes because the 3 phase supply would have a neutral connected. Usually the different wiring options are accommodated because it allows the load to be more balanced if 3-phase is used.

Maybe you can scan the installation booklet for the stove and attach pictures of the different wiring options if it shows the circuit diagrams.

 

[Dusan]

Thanks. Is this on the photo enough to make any conclusion?

 

[R G]

What you show here is what we also face on some of the cookers over here , the problem is that there may be a limitation on your supply over there , and I know in some parts of Europe that the cooker has to be split among different phases for that reason , so more information about the supply into the house and maximum permitted loads ,,

 

[Dusan]

I know that we have 25 ampères main fuses, and 16 ampères each group.

 

[Marvo]

Okay, from the diagrams, the first one is for a 230v single phase supply, the second is if you have two separate single phase supplies, third is for standard 3-phase connection with neutral, fourth is if you have a USA type supply where you have 230v L-L and no neutral, the last one is for a 2-phase supply with a single neutral.

I'm assuming the wiring scheme the electrician has recommended is the second one or the fifth one. Your preference is the third one which is 3-phase with neutral. In each of the wiring schemes the voltage across the individual heater elements will be 230v so in each of the wiring schemes the heating ability of the stove will be the same.

 

[Dusan]

I'm assuming the wiring scheme the electrician has recommended is the second one or the fifth one. Your preference is the third one which is 3-phase with neutral. In each of the wiring schemes the voltage across the individual heater elements will be 230v so in each of the wiring schemes the heating ability of the stove will be the same.

Many thanks. it is much clearer to me now.

The question I should have asked at the beginning is still here, though:

How to configure the wall socket, as per the scheme #2 or per #3?

 

[Engineer54]

You are the customer, therefore you tell the electrical company what you want, not them dictate to you what your going to get!! For a 3 phase supply with 25A service fuses, it would make more sense to spread the load over the 3 phases. Manufacturers don't provide a connection for a 3 phase supply if the product isn't suitable for such a connection. If they are worried about neutral loads, they should have installed a 5 core 4mm supply cable to the cooker socket... (L1/2/3 + N & E)

 

[Dusan]

You are the customer, therefore you tell the electrical company what you want, not them dictate to you what your going to get!! For a 3 phase supply with 25A service fuses, it would make more sense to spread the load over the 3 phases. Manufacturers don't provide a connection for a 3 phase supply if the product isn't suitable for such a connection. If they are worried about neutral loads, they should have installed a 5 core 4mm supply cable to the cooker socket... (L1/2/3 + N & E)

Thank you.

Although they are registered company and have very nice website, I think they have problems with understanding why distribution of power over 3 phases is better than over a single phase, as it seems very uncommon over here to have 3-phase in 'normal' houses kitchen, and they were just doing what they usually do with a single phase in a kitchen (while there are two additional 3-phase sockets which they put in the garage, where I plan to have 2 three-phase consumers (car bridge and and additional water pump to boost pressure - somebody whom I trust advise me never to use single phase pump, but three fase if I really want to see the effect).

I have just checked the sockets over there, and I see they are "real" 3 phase, but with one neutral wire, all 2,5 sqm. They knew why I wanted the 3 phase, so I hope this cross sections will be good for the purpose, I did not make my own research and calculations trusting they are professionals and should know, now I am very much concerned about how they made the fuse boxes and those leads in the garage.

The dispute over the kitchen socket is because it was left for the end, as position of kitchen elements was not planned, so they did bring 7 wires to there, 3 brown, 3 blue and earth, but in the fuse boxes they allocated two blues from one same phase for the 2x220 socket, instead of installing one additional 3 phase fuse configuration, and have real 3 phase in the kitchen. Now they do not want to work on those fuses boxes any more. The Dutch are very strange and difficult for communcation, and I was not foreseeing problems well, nor have I checked them during work (which would be impossible anyway)...