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Hi

I've been called to a problem where occasionally on cold start up the led low bay lights trip the breakers.

The two set ups are;

1. Mcb ncn hager 10 amp type c feeding 6 x 100w low bays and 1 x 150w low bay.

2. Mcb ncn hager 16 amp type c feeding 14 x 100w low bays

I have been told by the manufacturer that the maximum inrush current of their 150w fittings is 40A so I presume it's the same or somewhere near for the 100w fittings

I think I'm right in saying that the c type breakers trip somewhere between 5 and 10 times the rated current ie 50 to 100 amps for the 10 amp

Am I correct in how I'm looking at this? Is the only way to solve this issue by separating them out or some sort of timed start up where by they come on at different times?

I would be grateful for any suggestions
 
what size cable is feeding the lights?
 
IMO, the second circuit with 14 lights on it is way too many, I would have designed that differently and split it in half, as the cables are 2.5mm2 you could change that MCB to a 20 C type to see if it holds, the first circuit seems okay IMO, so unsure why it is tripping, and as you only have 1.5mm2 cable I would not change that to anything highter than a 10, are they on plug ins? if so unplug the 150 and see if the other 6 work fine, that is a start, then go from there, it is possible one of the ballasts on circuit one is playing up which is causing the tripping, and a last thing to try is to change the 10 amp for a new 10 amp, it isn't unheard of MCBs fail.
 
Yes that's along the lines of what I was thinking adding an additional circuit and separate it off from the existing. I believe the zs reading is a limiting factor to increase to a 20a type c but I need to check the reading when I get access

They are on plugs so I think thats a good idea to remove the 150w first of all on circuit 1

The only thing I was wondering though given the manufacturer stating that the maximum inrush of a 150w is 40A and I presume it' going to be something similar on 100w.

How many 100w of these fittings would you put on a c type 16 amp? If it were too many would the inrush weaken the breaker over time or is that not a consideration given it is only a mater of moments that the inrush happens?
 
If you were designing that circuit you would limit the amount of lights at 8, probably even 6, so 14 is ridiculous, the ballasts striking in a low bay will put a load on the system and 14 will be a lot, split the circuit in half.
 
First, I think the best solution is as suggested to re-organise the LED lighting final circuits to more than two. If you cannot then here is an idea.

Recently, I was doing some work to enable my brother-in-law to use a smaller (2.3kVA) mobile generator to run his fridges and freezers in his mobile catering vans. He uses 2.8 and 3.4 kVA generators at the moment simply to deal with the starting surge. I used thermistor inrush current limiters. Such devices have a negative temperature/resistance co-efficient which means when cold they have a higher resistance then when hot - they heat up through Ohmic heating effect of the load current and once warmed up enough have a low resistance. They are placed in series with the load. They are ideal for loads which have a long interval between being turned off and then on again - which allows the thermistor to cool down. So fridges, freezers and ...LED lights.

Here is a guide to how to select a thermistor for an LED application. A key thing to remember is to use the peak mains voltage of 1.4i4 x 240 = 350V when calculating the minimum resistance and 'Joule' Value.

Inrush Current Protection for LED Lighting Retrofits | Ametherm - https://www.ametherm.com/blog/inrush-current/inrush-current-protection-led-lighting-retrofits/

I used a normal surface box with a cover and a porcellain connector block to mount the thermistor inside it. I also used 85/90C rated flex inside the box.
 
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As you have got the information of the inrush current from the lighting manufactures it may be worth speaking to the protective device manufacturers technical department.I know that a few years ago I had this problem come up and looking at the data of the MCB manufacturer you could only put four 250watt SON fittings on a 10A C MCB.What is the ELI?
 
You could also try these ready made inrush current limiters which are designed to handle the high switch on transient current of capacitive loads like LEDs. After the electronics has dealt with the transient an internal relay switches to bypass mode. There is no reset period between switching off then on again. You can buy them for a range of steady state currents.

http://powersolve.co.uk/sites/default/files/camtec_esb101_e062016-01-0.pdf

ESB 101-33 - Peak current limiter, 33 A, 4000 µF - https://www.reichelt.com/gb/en/?LANGUAGE=EN&CTYPE=0&MWSTFREE=0&CCOUNTRY=447&ARTICLE=167635&PROVID=2788&wt_guka=54950995355_263550067601&PROVID=2788&gclid=EAIaIQobChMI8_W1qrHm2gIVqrXtCh0I5w3FEAQYAyABEgIA-fD_BwE
 
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The measured Eli on the 16 amp is 0.95 according to the results at the board not got up there yet to measure myself

Apparently they had 100w fluorescents previously and they had them switched out for these 100w low bay leds
 

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