Triphase/monophase

[jeffb]

Greetings and Bonne Annee, folks!

We have just completed on a house in Brittany, and intend to move by mid-January.  The property is separated electrically and has two electricity supplies (two meter boxes, etc, and presumably two separate bills) which each feed half of the house .  One (the modern circuit) is triphase, the other monophase (this circuit needs renewing)

We need to set up an account with EDF for the triphase supply side - and eventually will have the other part rewired and joined up to make one supply for the whole house.  The water heater and oil boiler I assume are triphase appliances (we may need to replace both soon) - a key consideration, and why I'm dithering about this!

My questions:

1. can anyone advise on weather it is best to keep the triphase, or change to monophase? Why?

2. most of our appliances and electrical equipment will come from the UK - can we just plug these into a triphase curcuit.  Will they work ok?

I have seen other threads discussing the triphase/monophase topic but not found the answers I need.  I will very much appreciate any help offered.

Many thanks

[Clarkkent]

My personal view is that if the building is to be used solely as a domestic house - ditch the three phase supply. Keep it simple.

I would not like the thought of 405v lying in wait to kill me. Except for the three phase water heater you will probably find that the supply is distributed as three single phase sets of spurs around the house, anyway. If the cumulus is due to be replaced soon, you can buy a single phase replacement in any of the sheds.

Any domestic appliances you bring from UK will be single phase (230v) and will work satisfactorily.

 

[AnOther]

Welcome to the forum and bonne chance with your new house,

My view would be similar although properly installed and maintained there is nothing inherently unsafe with a triphase setup. You say the triphase is the newer but does that mean new or or just relative to the mono, and crucially, is it in tip top condition ?

If you have the slightest doubt about it and think it may need a rework then I'd consider a switch to monophase but in any case you should try and get rid of one or the other because, whilst your overall bill for electricity consumed will be much the same, as they are 2 separate supplies you'll be paying 2 monthly standing charges.

But you may not have the choice. The principal reason for triphase was, and still largely is, to enable longer distances to be reached, 3x smaller cables sharing the load as opposed to one fat cable carrying it all, and it could be that you are still to far away from the source of your electricity to go mono. That said if one half of the property is already mono the foregoing probably won't be an issue but only EDF can tell you what your options are and give you a quote for converting.

[Anton Redman]

With the possible exceptions of the hot water cylinder and wiring to a very large electric cooker it is very unlikely the wiring on the out let side of the T d E is anything other than 230 volts. One curious part of EDF pricing for two 6 amp supplies is less than the standing charge for one € 12 amp supply. I believe the last three in the list are three phase only.

3 amps KW	15	€66,82	0,1078
6 amps KW	30	€77,08	0,1081
9 amps KW	45	€96,78	0,1125
12 amps KW	60	€168,13	0,1125
15 amps KW	75	€204,76	0,1125
18 amps KW	90	€241,40	0,1125
24 amps KW	40	€412,66	0,1125
30 amps KW	50	€560,19	0,1125
36 amps KW	60	€707,71	0,1125

[LesFlamands]

One problem with 3 phase against monophase is that if, for example, you have an 18kW tarrif with 3 phases you have only 6kW on each phase and your supply will trip if you overload one phase. If your kitchen is supplied by one phase you may find that you have to be careful how many appliances you run at one time.

I don't know what the rule is in France but in the UK there is a specified minimum distance between power outlets wired on different phases. If this applies in France then it may make it difficult to supply the kitchen from different phases to spread the load.

As someone else pointed out, EDF can be reluctant to change you to monophase depending on your distance from the sub-staion and the existing cable size.

[dragonrouge]

Please may I join this posting and also ask for advice. We have Triphase in the house and much earlier in the piece 2007 and when we moved from Normandie the 'general' view was that triphase was not inherently dangerous and the earlier posting now starts we worrying once more.

Briefly our house was owned by a coach operator and in the huge courtyard there was a hangar an inspection pit and the like.

My understanding of his need for triphase was the need for power washers pumps and the inspection pit. All of this has now gone.

Within the house two of the phases has been completely rewired and in the third (the courtyard area we only use say a fridge and freezer in the dependance plus lighting from time to time. We are also in the courtyard area now to install a halogen light for security.

The electrician comes on Friday next what should I ask him. There is a overhead cable that runs from the house to the courtyard area. We have 5kw on each of the triphases and as one of the postings says the monthly charge reflects this. Really would appreciate guidance and help.

[dragonrouge]

Sorry I forgot to mention that I know exactly nothing about the subject area so hence the request for help?

[UlsterRugby1999]

[quote user="Anton Redman"]

With the possible exceptions of the hot water cylinder and wiring to a very large electric cooker it is very unlikely the wiring on the out let side of the T d E is anything other than 230 volts. One curious part of EDF pricing for two 6 amp supplies is less than the standing charge for one € 12 amp supply. I believe the last three in the list are three phase only.

3 amps KW	15	€66,82	0,1078
6 amps KW	30	€77,08	0,1081
9 amps KW	45	€96,78	0,1125
12 amps KW	60	€168,13	0,1125
15 amps KW	75	€204,76	0,1125
18 amps KW	90	€241,40	0,1125
24 amps KW	40	€412,66	0,1125
30 amps KW	50	€560,19	0,1125
36 amps KW	60	€707,71	0,1125

[/quote]

Hi Anton - could you (for those thickos like myself) add a wee bit more meat to the data table you posted. Presently, we have Triphase with each phase operating one area of the house only and no actual three phase appliances. Is it difficult to switch over to monophase? Cheers - and sorry if it is being deemed a thread hijack.

[AnOther]

It's may be best to explain the difference between mono and tri phase then let you decide if anything about the way your property is wired gives you cause for  concern. I'm ignoring the Earth because it is not really relevent in the context.

With mono or single phase you have but a single supply of 240v (1x Live & 1x Neutral) coming in hence that is the highest voltage available to potentially harm anyone under any circumstances.

With tri phase you have 3 individual supplies of 240v (3x Live & 1x Neutral) the significant difference being though that between any two of those lives you now have 440v, clearly a far more deadly voltage.

Any danger from triphase hovever comes ONLY from any situation where it is possible to come into contact with 2 lives at the same time and thus receive a shock of 440v.

Apart from items of equipment which require a 3 tri phase supply, such as water heaters etc, best practice would be to arrange the wiring in a property so that this is impossible. On a very simplistic and idealistic level, an example might be in a 3 storey house where you might wire each level from it's own phase for  perfect separation. Unfortunately modern living, where you typically have a concentration of high demand items in the kitchen say, can often make that difficult to achieve but that's not to say that having 2 or even all 3 phases in the same room is necessarily dangerous so long as the installation is correctly carried out and is in good condition.

Hope this is clear enough.

NOTE: I do not know what the French regulations say about any of the above, it is merely offered as a broad outline description of the differences between the 2 systems and the potential dangers.

Happy New Year

[Dave&Olive]

[quote user="Anton Redman"]

With the possible exceptions of the hot water cylinder and wiring to a very large electric cooker it is very unlikely the wiring on the out let side of the T d E is anything other than 230 volts. One curious part of EDF pricing for two 6 amp supplies is less than the standing charge for one € 12 amp supply. I believe the last three in the list are three phase only.

3 amps KW	15	€66,82	0,1078
6 amps KW	30	€77,08	0,1081
9 amps KW	45	€96,78	0,1125
12 amps KW	60	€168,13	0,1125
15 amps KW	75	€204,76	0,1125
18 amps KW	90	€241,40	0,1125
24 amps KW	40	€412,66	0,1125
30 amps KW	50	€560,19	0,1125
36 amps KW	60	€707,71	0,1125

[/quote]

                      some one has got their kv Amps and  amps `s   mixed up

                                                       Dave   [8-)]

[LesFlamands]

Some older 3 phase installations have what are known as 'prise de force'. These are 3 phase power outlets usually intended for 3 phase heaters and sometimes cookers. These PdF can either have 4 holes (3 round and one rectangular) which are the three phases and earth or 5 holes which are the 3 phases,neutral and earth. With the 4 hole outlet there is no neutral and the only voltage available is between the phases (380volts) but I have found these wired with the neutral on the earth pin.

Any older installation with these PdF still in place should be checked very carefully.

EDF will change your supply to monophase simply by changing the meter and leaving 2 of the phases disconnected on their side and simply connecting all three phases together on the consumer side. This will be fine as long as you don't have any 3 phase motors. The problem may be that they are unable to give you the same tarrif due to the cable size and the distance from the sub-station

[jeffb]

Thanks to everyone for their replies, they have all been very helpful.

I have never been that interested in electrics before - it's amazing how necessity presents opportunity to learn a new subject, though.

We have now managed to set up a new contract with EDF and will maintain the current triphase supply untill settled in.  I think our first priority is to get an expert to look over everything and ask advice on options face to face - language difficulties permitting!

This forum is such a godsend for newies like us.  It is reassuring to know there is so much knowledge and experience we can tap into.

Cheers

Jeff