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2 phase

Job description

Posted 2 years ago

I have a particular problem with the electrical supply to the fuse board and our regular electrician has not been able to solve it.
So I am sending you this email in the hope that you might know what to do. If you do, then you get the job of fixing it. Plus any other work that comes up too.
The fuse board is supplied with two phases each one separately metered. But there is only one neutral and one earth link. The difference between the current in the phases and that in the neutral produces an imbalanced pulsing magnetic field along the track of the link, about 8m. I measure the field reaching up through the floor to nearly 1m with a strength of 1mG.
That would not matter except that the owners and occupiers who must walk through the field are hyper-electro-sensitive and the magnetic field is affecting them.
The two phase supply is effectively producing a 60º offset in the pulse which when opposed to the single phase power circuits at 0º or 120º offset produces capacitance through parts of the building.

Of course the heavy duty cable is hidden in the floor-ceiling cavity and the owners don’t want the decor damaged.
I wondered if one phase could be disconnected and the whole network run from one phase, so that the live and neutral were brought back into balance.
A second cause of magnetic flux is a single core supply to the hot water cylinder with the neutral being diverted to a common return.
Sharing neutrals is not allowed in other countries because of overload potential and imbalance.


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