Hi All

Hi all, I have just joined your forum while looking for help in tracing a bank of LED lighting and 40 amp 230 volt double pole contactor tripping the MCB and I am very pleased with your forum and how much help there seems to be.

Hope I can be of help to some of you.

Captain J

Aye aye Captain !      Welcome to the Forum  .  Want to give some more information on  your problem .  

I'll take a flier at it and say  ...  start up   inrush   ..based on ..erm  ..nothing really. 

Welcome Capt’n, 

As first officer Deke suggests a greater info reccy will be required to determine course of action sir! 

don't get too comfortable you will not be getting the sir bit anymore!! 

Hi Deke and thank you for your prompt response. My problem is in our storage yard area we have a bank of approx. 12x led flood lights that is switched into a switch with Auto (top) which is wired to a photo cell. Off (middle) and Manual (bottom) It then goes to an box containing a 230v 40 Amp 2 Pole Contactor but it started to trip the 6 amp mcb now and again but on Friday it tripped and wont come back on. I don't know if its a fault with the contactor or photo cell and its just that they are up high so I was looking a bit of advice if anyone had an idea where to check first.

Thanks again and Thanks in advance

Captain J

Sharpend said:

Welcome Capt’n, 

As first officer Deke suggests a greater info reccy will be required to determine course of action sir! 

don't get too comfortable you will not be getting the sir bit anymore!! 

Click to expand...

Hi Sharpend, Thanks for the help. I have tried to explain a bit in the post above. Once again Thank you for your response. Captain J

What do you have in terms of test gear? A multimeter? 

Have they been working for ages or just a short time  before  the tripping started .  ?

How many  LED fittings are there and what is the total wattage ?   

Just wondering if the 6 amp MCB  has given up after much tripping . 

Is that 6amp MCB JUST the control circuit, (ie the photocell and the coil of the contactor), or is it also powering the lamps themselves?

sounds more like damp in the system to me, but LEDs can have a high / but short lived surge on start up. 6A is good for roughly 1.5kW, so I doubt even 12 flood lights is an issue unless they are very hgh wattage in LED terms? 

I have been in lengthy discussions with ZANO recently

some of the inrush currents they have measured from LEDs on startup are phenomenal even if only transient

they are, but usually so short as to not bother an MCB in any form, and certainly not a Type 'C' 

As suggested, the MCB itself may have given up. I still think the inrush from 12 LED drivers could be damaging.

I'm assuming you are sufficiently knowledgeable / competent to undertake fault finding!

Remove the output wire from the MCB and see if it will reset now. If it does, it's probably OK.

If it trips when re-connected, but with the light switch OFF then you have a short somewhere in the control circuit, ie the contactor, photocell or switch itself.  -  it can't be the lamps or their wiring if they are controlled via the contactor.