LEDs tripping type 2MCB!

hoppy · Jun 2, 2017

hi

I have recently done a job, replacing 17 down lights in a kitchen with 17 x 10w led down lights and replacing 7 under cabinet lights with 4 x led strip light kits (4 drivers).
They are on a type 2 mcb, the downlights are split across 2 switches and the under cabinet lights are on their own switch (it's a 4 gang switch), but the Mcb trips when the under cabinet lights are turned on, but not all the time. I have IR tested the cables, all above 100 mega ohms.
So I am a bit puzzled, could this be an over load / in rush issue?

Thanks

Craig

dmxtothemax · Jun 2, 2017

In rush or harmonics,
That many electronic supplies would produce lots of hash
Have you tried using another brand of driver ?
Try feeding the main supply thru a 1 to 1 isolation transformer
The iron core tranny will filter a lot of the hash out
And also reduce back EMF

Deleted member 9648 · Jun 2, 2017

Depending on disconnection times being met change the type 2 mcb for a C/D curve, or a fuse. Some older DB's take cartridge fuse carriers as well as MCBs, Hager for example.

Midwest · Jun 2, 2017

I think its pushing the boundaries a bit, e.g. JCC installation instructions for their FGLED10, suggest limiting 'maximum no of fittings linked per circuit' to 14, on a C type 10a mcb.

So home owner switches on all the lights, like they do with one hand, will trip the mcb. What does the manufacturers of the down lights and stripe lights say? What's the combination of switching?

Octopus · Jun 2, 2017

What happens if the under cupboard lights are turned on (and the down lights are left off)?

hoppy · Jun 2, 2017

Murdoch said:
What happens if the under cupboard lights are turned on (and the down lights are left off)?

It trips the mcb, the downlights don't trip the mcb, it is only the under cupboard ones that trip it, it's not every time, but happens a lot

davesparks · Jun 2, 2017

If the only thing that has changed is the installation of the lights then it can only have been caused by you installing the lights.

What steps did you take to establish that the existing circuit is suitable to supply this quantity of LED lights before you fitted them?

Octopus · Jun 2, 2017

Hum......did you supply the parts?

Midwest · Jun 3, 2017

hoppy said:
It trips the mcb, the downlights don't trip the mcb, it is only the under cupboard ones that trip it, it's not every time, but happens a lot

What are the make/model numbers of the under cupboard luminaires?

hoppy · Jun 4, 2017

Murdoch said:
Hum......did you supply the parts?

Yep
I supplied the parts

hoppy · Jun 4, 2017

davesparks said:
If the only thing that has changed is the installation of the lights then it can only have been caused by you installing the lights.

What steps did you take to establish that the existing circuit is suitable to supply this quantity of LED lights before you fitted them?

The total load of the new led lights is 200w it is not a load issue, so what else would I need to establish, the ir readings are good, the zs is ok.

Octopus · Jun 4, 2017

^^ so the onus is on you and your pocket to sort it out

davesparks · Jun 4, 2017

hoppy said:
The total load of the new led lights is 200w it is not a load issue, so what else would I need to establish, the ir readings are good, the zs is ok.

does that 200W represent the power of the leds theS elves or is it adjusted for the efficiency of the drivers, what is the inrush current for the particular drivers and how long does it last for? What do the manufacturers have to say about the maximum number of fittings per circuit?

Octopus · Jun 4, 2017

hoppy said:
The total load of the new led lights is 200w it is not a load issue, so what else would I need to establish, the ir readings are good, the zs is ok.

200 w of led lights sounds very bright. Are you sure that is correct? Is this a house or a commercial premises?

Midwest · Jun 4, 2017

The OP said he installed 17 x 10w down lights = 170w. So I'm guessing the remaining 30w is for the under cabinet lights, the ones causing the issue?

Edit; Be nice if he posted details of the troublesome luminaires.

Octopus · Jun 4, 2017

^^ OK lets use 30W as the under cupboard lights - so best option would be to disconnect 1 lamp or transformer to see if it improves.

Wonder how many other lights are on the circuit? How many are on when it trips?

My pennies are on inrush currents...

Delboybully · Jun 4, 2017

I had this once. Same situation. Need led spots and led under cupboard lights in 3 sections fed from 3 transformers. Turned out one of the transformers was faulty

hoppy · Jun 6, 2017

Thanks for the replies.
Apologies been really busy, I haven't been back to the property yet, the drivers are Ngl uk ltd, input 1 amp and output 3 amp, I have no other information about them.
The circuit trips only when the under cabinet lights are o and no other lighting.
I am thinking it is the In rush current as it doesn't happen all the time and it is when they are switched on, not when they have been on for a bit.

dmxtothemax · Jun 7, 2017

What happens if you only switch on the under cabinet lights with nothing else on ?

marconi · Jun 7, 2017

A suggested solution: Buy some Negative Thermal Coefficient (NTC) Thermistors and insert one in series with the line feed to the LED driver. See:

ntc thermistor | Rapid Online - https://www.rapidonline.com/Catalogue/Search?query=ntc%20thermistor&filterSearchScope=1&tier=NTC%20Inrush%20Limiters

Install the NTC thermistor inside a suitable non-flammable enclosure with the thermistor not touching the sides.

An NTC thermistor has a negative thermal co-efficient which means at low temperature (eg ambient) its resistance is high, but as current flows through it and ohmic heating occurs its resistance decreases to a low value. For example for a 2A thermistor its resistance is 50Ω at zero current and at 2A 0.8Ω. At 2A and operating temperature the volt drop will be 1.6V and the power dissipated is 3.2W. See link and technical specifications and data sheets. You might want to do a trial first.

Instead of inserting the thermistor in the line feed you could also try inserting one in series with a pole of the LV output side or perhaps one in series with the feed to each LED luminaire. The former is probably a better idea because the latter might result in uneven brilliance from the luminaires.

1Justin · Jun 17, 2017

A good idea that @marconi. I had a lot of trouble with a load of Meanwell LED drivers in the past for external floods.
That trick may have saved me a load of a headache, and eventually needing a 16A D type for a 1 Amp load (Fortunately the numbers just worked out.. but it had me sweating).