Got a problem

[alonzo]

When extractor fan is on,hf digital ballast lights dim,lights and fan are not on same phase,I've checked neutral connections,anyone got any ideas to cause of lights dimming?

 

[Electro-tech]

Its not a load issue.What rating is the Fan,are the circuits fed from a sub mains board?

 

[alonzo]

Board is not sub mains,checked loads are balanced over phase's thats ok,fan controller is fed via switched fused spur with 10A fuse.

 

[Electro-tech]

I would have thought there must be something in common to both phases or circuits.Are they totally seperate.

 

[alonzo]

Both circuits are separate,the only thing in common is neutral connection,they are fed from Rcbo's,maybe it's the neutral connection in the rcbo,I also disconnected one of the lights and connected a pendant with normal filament lamp and it did not dim when fan was on.

 

[Electro-tech]

I would have thought that to dim a ballast you would need to alter the voltage and not the frequency. I cant see it being volt drop.
It cant be a imbalance between live conductors of that importance or you trip the RCBO.Maybe change for a MCB temporarily on just the lights to test.If ok then it must be linked to the Neutrals.

 

[Knobhead]

It’s most obviously a neutral problem, can you get your hands on a clamp meter that will measure harmonics?
Out of interest have you measured the voltage between neutral and earth at the local board?

 

[alonzo]

Going back to job thurs,will change rcbo to mcb to test,can't get clamp meter,havnt tested between neutral and earth but will do,thanks for input and help let you know results.