it's regarding this PSU from Mean Well:


It has a 60A inrush current. My lighting circuit (1.5mm2 wiring) is tied to this PSU supplying 24VDC power to led strips.

My question is which type of MCB should i use for my lighting circuit?

Usually either B10 or C6 is standard here for lighting circuits but clearly it's not suitable here since the min trip current would be 30A x 1.4 = 42A which is well below 60A.

So i am considering C10 or D6, but are they normal for lighting circuits? D6 seems to be better since they have higher max Zs than C10. Here's a table from Hager showing the max circuit length for 1.5mm2 wire.

Max Circuit Length

There's no data for D6 but i am assuming it would have more allowance than C10 which allows for 82m of run.

The max length of the circuit for this project is well below 20m so i assume either C10 or D6 should be alright?

Taking into consideration the circuit has quite a number of 5w GU10 LEDs (15 pcs, hence higher inrush), am i correct to assume that D6 (6x10x1.4 = 84A) is better than C10 (10x5x1.4 = 70A)?

I am just concerned with the use of type D because almost no one recommends it for domestic use so i was wondering if it would cause any problem.

Or given all the above, it wouldn't have mattered since the inrush current of the PSU may have happened too fast for the tripping to occur? The Mean Well documentation does not state how long it lasts but it seems to be 10ms: https://www.meanwelldirect.co.uk/glossary/what-is-inrush-current/.



1 Answer 1


You need to be looking at the trip curves for MCBs when planning for inrush:

B, C, D MCB Trip Curves https://studyelectrical.com/2014/07/miniature-circuit-breakers-mcb-types-characteristic-curves.html#Selection_of_Right_MCB

You can see that 10ms and below is not on the graph. Inrushes below 10ms will not cause a trip, by design.

From having designed similar equipment I would suspect that your inrush will be barely in the milliseconds if you were to measure it.

In any event, a B10 MCB would be a sensible choice here.


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