Has anyone seen 3 phase lighting

[Adp]

Hi new to this, has anyone ever seen lighting on a 3 phase breaker ? A company wanted to use a 5core swa and and share the neutral for using on the other 3 phases, they were told they can’t do this but have now decided to try get round it by using a 3 phase breaker. This is in a 3 phase board and the lighting is going round a premises. Surely this can’t be right ???

 

[littlespark]

The lighting would have to run on 400v, not 230v

Probably can’t be done.

Why were they told they couldn’t have 1 neutral for all 3 phases?

 

[westward10]

It is not uncommon on large lighting installations to have groups of lighting across a three phase protective device using a single neutral conductor provided the protective device is linked so all lines simultaneously trip. See Reg 559.5.5

 

[Adp]

They were wanting to have say 1L1 5L1 and 8L1 with one neutral, if you isolate one of these to work and the one you work on may become live. Yeah it’s one linked protective device. I just think it’s silly as if there is a fault with one phase you lose all lighting.

 

[westward10]

They can't use a triple pole linked device across the same L1 line it needs to be 1L1, 1L2 and 1L3. It is perfectly acceptable to use this method.

 

[shaun1]

There would be no benefit to running the same phase down 3 cores with one neutral as the neutral conductor would need to be sized to carry the 3 combined phase currents so you might as well use one live. If they want 3 individually switchable circuits, I believe a 5core SWA could be used if all the switchable circuits were fed from the same MCB and so had 1 point of isolation.

Otherwise, as mentioned above you could run a 3ph circuit with 230v lights split across the 3 phases.

 

[Deleted member 26818]

There would be no benefit to running the same phase down 3 cores with one neutral as the neutral conductor would need to be sized to carry the 3 combined phase currents so you might as well use one live. If they want 3 individually switchable circuits, I believe a 5core SWA could be used if all the switchable circuits were fed from the same MCB and so had 1 point of isolation.

Otherwise, as mentioned above you could run a 3ph circuit with 230v lights split across the 3 phases.

No the neutral wouldn’t.

 

[The Ghost]

No.

 

[shaun1]

The Neutral wouldn't what?

 

[westward10]

No the neutral wouldn’t.

I believe it would, three circuits with a shared neutral where the three circuits are connected to the same line of the three phase supply, linked protective device or not. It is only feasible when they are across separate phases.