3 Phase electricity transformer

[cjevans4u]

My wife and I run a chambres d’hotes from our property which is in a remote area in the south west of France. We have a 3 phase electricity supply which is spit at the consumer unit for different cicuits. I have converted our barn for additional bedrooms and summer kitchen and have run a cable (about 40m of 2core 10mm sq) from one of the phases and neutral in the consumer unit to the barn for its power requirements. However, the voltage at the barn end is less than 200v (at the consumer unit it is only about 220v) and I find that when the water heater in the barn cuts in there is a power dip and the lights dim.

My question is this. Would a practical solution to the problem be to install a 3 phase transformer in the barn and run all 3 phase to it and then take off different circuits for the power and lighting circuits? If the answer is yes what winding configuration on the transformer would be best (i.e. Y or Delta)? Are there any configurations that would not be allowed? Also, would EDF have any objections to what I propose?

 

[wingcoax]

Not sure of regs in france but would go for delta.

 

[Paul_C]

However, the voltage at the barn end is less than 200v (at the consumer unit it is only about 220v)

220V is quite normal in France, as that was their nominal supply voltage for many years (just as in Britain it's still really 240V in most places despite playing with the allowable tolerances so that "officially" it can be called 230V now).

Anyway, a 20V drop along the cable suggests that it isn't heavy enough for the load (over the stated length it also suggests you're exceeding the cable's current rating with that load). Either that or you have a bad connection somewhere which needs fixing.

I'm assuming the 220V measured at the main panel is with the load in the barn drawing power? What power is the water heater?

My question is this. Would a practical solution to the problem be to install a 3 phase transformer in the barn and run all 3 phase to it and then take off different circuits for the power and lighting circuits?

I can't see much practical advantage to doing that over the distance involved. You'd have to replace the existing cable with a 3-core one anyway, and the cost of a multi-kVA transformer on top of that is likely to work out more expensive than installing a heavier 4-core cable to just extend your existing 220/380 wye system to the barn.