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Finished a refit of 7 x 200watt led lights to existing circuit.
The orignal circuit had 120 watts per light,so 140 watts x 7...say 1kw.
These are 1.4 kw,so not really loading the circuit.
There are other lights on the circuit,it’s a 10amp b type MCb.protecting it.
The lights are working, & suddenly without any reasoning mcb trips,they can be on all day,& never tripped when switching on off,over several days.
But will trip randomly.
Any ideas,I’ve switched they repeatly on off to see if I can trip the mcb,but never trips on that.
 
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Gavin John Hyde

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Arms
Esteemed
could be in rush current?
The rated wattage/lumens in itself isnt the issue its the inrush draw of the transformers. can be several times the actual rating of the light. some fittings are worse for it than others.
I had it recently, according to the lighting design people who specified the job the 10 high bay led fittings at 8500 lumens each (all these in the warehouse would have been on a 10A Type B) the design people specified a type b and had same problem as you.
Tripped randomly when turned on.
Swapped for a Type C 10A and all hanky dory as they say.

you should also check the light data sheet, some led fittings are very poor quality and use cheap chinese crap inside, some transformers are just current drains and get hot. likewise not all leds are equal.
 

pc1966

Arms
Esteemed
If tripping on switch-on then inrush is the obvious answer.

If tripping at odd time is could be a very poor power factor so the RMS current is well above the stated power level. If you have access to a clamp ammeter that has true RMS (or similar) characteristics you could measure what is actually being taken.

Final thing is a bad connection really causing a fault current, so taking L+N together and testing insulation to E might show something.
 

davesparks

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Mentor
Arms
Esteemed
The OP says they trip after being on for a period of time so it can't be inrush at switch on.

As per Pc1966 it could be poor power factor leading to overloads.

Or there may be supply voltage fluctuations causing the LED drivers to suddenly draw more current as they try to maintain constant power output.
 

GBDamo

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Supporter
Are all the lights on this circuit on one switch?

If they are on multiple switches then they may never all come on together and challenge the MCB.

If there is a blip that cuts power for a fraction of a second they then all come on at once and inrush may come in to play.


In truth, I stopped reading half way through the OP and just plumped for inrush.
 

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