New LED Drivers Tripping RCB

[JonoJono]

Hi

Background

I have just replaced my MR16 incandescent bulbs with LEDs in my kitchen ceiling. There are now 12 identical bulbs, rated at 5w (total 60w). To power these I have fitted 2 X 60W LED drivers, (each running 6 bulbs) so the drivers only need to work at 50% capacity, and both these drivers are powered in parallel by one switch.

Problem
The problem is the MCB (Crabtree SB6000 - 6A Type 1 (old Type B)) is often tripping when I switch the 12 lights on. Sometimes it doesn't trip however, and when it is working the kitchen is lit beautifully for hours with no problem.

Comparison
There are also two different lighting circuits in the kitchen using the same make & model of bulbs and drivers, and these work without any problem. These are:
 - 1 X 5w bulb on 1 X 60w driver - on one switch.
 - 5 X 5w bulbs on 1 X 60w driver - on one switch.

HELP!
Doing some research I see there are two possible solutions:

1 - Replace the Type B MCB with a Type C - though I cannot find my make/model online - probably because everyone else has had the same problem! (Crabtree SB6000 6A Type 2 required to replace 6A Type 1).
2 - Install an Inrush Current Limiter.

If you can provide some helpful advice (most inexpensively if poss!) on what I need to do to to correct this would be appreciated. 

Thanks in advance.

EQUIPMENT:

LED Driver: https://www.amazon.co.uk/s?k=B016KFT536&ref=nb_sb_noss
Bulb: https://www.amazon.co.uk/s?k=B082B4QG1X&ref=nb_sb_noss

RCB: https://willrose-electrical.co.uk/product/crabtree-sb6000-mcb-6-amp-single-pole-breaker-type-1-6a-61006/

 

[ProDave]

Have you tried fewer lamps?  Any current measurements?

 

[Evans Electric]

I'd say its the   start-up inrush of current ,   common with LED.    If you can't find a Type C   try a 10A    B type .

 

[JonoJono]

ProDave - Thanks for that. I'll do a test and advise how many work before it starts to fail.

@Evans Electric - thanks for that; I'll have a look online to see if I can find a 10A Type B.

 

[binky]

Never heard of that driver make, and it seems to be specced at 240V - you need drivers specced at 250V or ideally slightly higher for UK as mains voltage can be as high as 253V  

 

[Sharpend]

I’ve never known leds to trip an mcb, it could just be a poor termination on the Ops part, too much insulation removed? 
or even dare I say a poor Chinese quality driver? 

 

[roys]

How about convert to LED GU10?

 

[Evans Electric]

I've noticed warnings on LED  concerning  inrush currents  along with a comment to look at smaller circuits .   

 

[Doc Hudson]

How about convert to LED GU10?

That would have been my preference as well. MR16 push connection pins are a pain in the rear. Unless there is a specific requirement for 12v fittings, (e.g. bathroom zones), I cannot see why anyone would (a) keep extra links in a circuit that can introduce additional faults,  or (b) have multiple lamps off a single driver, so a single failure wipes out several lights. Not to mention if you are still using Type 1 MCBs, your board is probably quite dated, (does this amended circuit include RCD protection?),  so an upgrade to a more comprehensive RCBO supply arrangement would also be a distinct advantage on reliability, functionality, and compliance with current regs. If you are changing to a different Type or Current rating, you will need to verify that the Earth Loop Impedance (Zs) is still within acceptable limits.

Doc H.  

 

[JonoJono]

Hi all

Thanks for all your feedback, and just to update you.

 - The MCB can trip with as little as 3 5A bulbs connected. I have come to the conclusion it is the >1 transformers loading concurrently that causes the spike/inrush which trips the MCB. Note: the circuit with 5 bulbs on one transformer does not trip the same MCB.

 - I am reluctant to put a 10A MCB in place of the 6A, as it protects the whole downstairs (of an old house) and would be too high rated for existing wiring.

 - The reason for not going GU10 was to keep it to the same as the previous installation (being MR16 12V), and there is a bathroom above, and we have kids that splash water!

 - I will probably end up getting an inrush current limiter, but in the meantime will reconfig the lighting to 1 X 60W transformer running 8 X 5W bulbs (40W) so there is still headroom of 20W on the transformer. The Crabtree SB6000 Type 2 6A MCB is a rare as hens teeth!

 - At some point I will get a sparky in to test the house's electrics and install a modern consumer unit.

I do notice that the MCB tripping is intermittent - occurring approx 1 in 4 times. When it doesn't trip, the MCB does make a knocking sound - other sites say this is the solenoid, and isn't ideal.

Getting right out of my technical depth, info I have found suggests that the intermittent nature could be based on where in the sin wave the AC current is at the point the inrush spike occurs. If it's at the peak of the amplitude then it will trip the MCB; if it's more near the centre between the peaks then it will not trip, and this is when a knock is heard on the MCB.

Hope that helps, thanks.

 

[Murdoch]

Hi all

Thanks for all your feedback, and just to update you.

 - The MCB can trip with as little as 3 5A bulbs connected. I have come to the conclusion it is the >1 transformers loading concurrently that causes the spike/inrush which trips the MCB. Note: the circuit with 5 bulbs on one transformer does not trip the same MCB.

 - I am reluctant to put a 10A MCB in place of the 6A, as it protects the whole downstairs (of an old house) and would be too high rated for existing wiring.

 - The reason for not going GU10 was to keep it to the same as the previous installation (being MR16 12V), and there is a bathroom above, and we have kids that splash water!

 - I will probably end up getting an inrush current limiter, but in the meantime will reconfig the lighting to 1 X 60W transformer running 8 X 5W bulbs (40W) so there is still headroom of 20W on the transformer. The Crabtree SB6000 Type 2 6A MCB is a rare as hens teeth!

 - At some point I will get a sparky in to test the house's electrics and install a modern consumer unit.

I do notice that the MCB tripping is intermittent - occurring approx 1 in 4 times. When it doesn't trip, the MCB does make a knocking sound - other sites say this is the solenoid, and isn't ideal.

Getting right out of my technical depth, info I have found suggests that the intermittent nature could be based on where in the sin wave the AC current is at the point the inrush spike occurs. If it's at the peak of the amplitude then it will trip the MCB; if it's more near the centre between the peaks then it will not trip, and this is when a knock is heard on the MCB.

Hope that helps, thanks.

I think you need a competent spark ..... a single transformer should not be tripping an MCB

 

[JonoJono]

I think you need a competent spark ..... a single transformer should not be tripping an MCB

It's only the multiple parallel transformer config that trips the MCB; the single transformer doesn't.

 

[Murdoch]

Multiple transformers shouldn’t be tripping an mcb 

 

[binky]

No transformer should trip the cct. 

In rush current for LED is so short lived it shouldn't trip MCB either - I've installed kWs of LED floods on Type B MCBs with no issues.  Reckon you either have a small cable fault, poor termination work, or cheap nasty transfomers.