415/240 transformer should you earth one leg to make a new neutral ?

[jar]

Hi All,
Im more of an installation man but do sometimes have to build or mod small control panels.

My brain and memory states that only a true neutral comes from the star point at the supply transformer provided it is connected to earth.

I often find transformers in 3 phase (no neutral) mcc wher one leg of the output side of the transformer is tied to earth and everything from there is wired as if there was a proper neutral. Single pole mcb from there on etc.

This alarms me but I cant find anything in regs to cover this. I dont feel this is safe or good practice.

When I was serving my time it was normal to use a 415/240 transformer then double pole all controls mcbs etc on the load side to run any 240v control eq etc.

I look forward to any opinions

 

[netblindpaul]

E Stop
BS7671 does not apply to machinery control panels so if you are doing machinery mods you must realise this and apply the relevant standard rather than looking to something that is irrelevant.

 

[Inteificio]

What is the relevant standard?

 

[Knobhead]

The leg of the transformer that is tied to earth is a proper neutral. It’s no different to a single phase transformer supplying a house. But chuck 7671 away!