LED floodlights causing induction hob to flicker on and off

Question

A friend has a barn, the supply is fed from his house into a DB in the barn, (not sure if fed straight from the incoming supply in his house, or fed from a way in his DB board in his house) 
 He has LED floodlights (450w) x 10 in his field, fed from a way in his DB in the barn. 
 When he has over 6 of the floodlights on, the induction hob in his home, fed from his house DB is flickering on and off. 
 Has anyone got any clues as to why this is happening? 
 The barn has a TT earth setup.

Simon Barker · Accepted Answer

Have you measured the voltage at the hob? I wonder if it's dropping below 217V and causing the hob to malfunction. 
 Alternatively, if they are cheap LED lamps, the power factor may be terrible, and the resulting mains is only vaguely approximating to a sine wave. That could cause problems with the hob's internal ELV power supply, in turn causing the microcontroller to keep resetting.

mapj1 · Answer

Is there any sort of EMC filtering in the line to the lights ? - Note that the reference levels of what is permitted when CE marking, in terms of how much high frequency crap you can inject into the mains were set based on one unit interfering with victim equipment in a neighbouring property. (mil spec standards are in most cases at least 20dB tighter, but that would make stuff more expensive) 
 It does mean that you can not guarantee that co-siting of interference source and victim will always work, nor does it consider the possibility of multiple potential interference sources in parallel. 
 You have both, I think. 
 Waving a medium wave or long wave (AM) radio near the wiring (any part of it not in earthed armour or steel conduit)when the LEDS are on and seeing if there are noise like radio signals that stop when the lights are switched off is a quick way of deciding if that is a possibility. 
 But do check the voltage drops first, not least because it is easier. 
 Mike.

LED floodlights causing induction hob to flicker on and off

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