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Two Phase CU

richard64
Good morning,


Came across a strange one doing an EICR yesterday.

The fuse board is fed with two phases and one neutral...phases L2 and L3 are linked.

I'm looking for a coding or deviation.

As I see it, best way is it's unbalanced loadings with pressure on the neutral.

Worst way is two supply circuits with a shared neutral.

The spare phase is being used to supply a flat in the building.

Loading wise, it would be possible to link out all phases in the main CU, making it a single phase board...but that would only push the problem back to the intake.

Any suggestions please.
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    That is an inherent problem with single-phase loads on a 3 phase supply. It is no different to any 3 phase board, and a full size (as phase conductors) neutral is quite adequate. It MUST not be coded and is not a problem! Whether RCDs are required at this point depends on the installation but would only code a C3.
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    That is an inherent problem with single-phase loads on a 3 phase supply. It is no different to any 3 phase board, and a full size (as phase conductors) neutral is quite adequate. It MUST not be coded and is not a problem! Whether RCDs are required at this point depends on the installation but would only code a C3.
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