Lighting Circuit Blowing 5A 1361.

[securespark]

Got a strange one.

One lighting circuit supplying:

1x 4 spot GU10 = 200W.

11x 50W SELV dichroics.

4 x 18W under-cupboard flu's.

Problem:

Fuse blowing, but not every time, on switching the 11 SELV fittings on.

IR OK.

Surely the start-up current is not that much?

Even with GU10's and flu's off, the SELV dichroics still trip.

Often trips on first switch on but can trip after lights have been on. he lights do not seem to trip when they are already on.

Any light to be shed please?

Cheers!

 

[17thman]

how have you measured IR?

 

[riveralt]

How many transformers are being used per light?

 

[Lectrician]

And are they el-cheapo trannies? I have known some cheapy ELV trannies randonly trip MCB's - An absolute PITA to fault find!

 

[securespark]

Measured IR L-E and N-E from CU with lamps out, but excluding the SELV stuff: clear reading.

Have not actually got round to examining the SELV kit, I assume one tx per fitting.

If they were toroidal, I suppose the in-rush could blow the 5A 1361 fuse.


SELV: 11 x 50W = 550W
GU10: 4 x 50W = 200W
FLU's: 4 x 18W = 72W

Suppose I could change all 11 trannies... If it is an in-rush problem, soft-start will help.

 

[Adam_151]

I'd definatly suspect an inrush problem, the electronic 'transformers' are basically switch mode power supplies (same as in computers) which are known to have high inrush when switched on after being off for a while as the capacitor charges up.

Its the similar to the old chesnut of the office or classroom with lots of computers, there being a power cut and when it comes back, the computers all receiving power back at the same time knocks out the B32 breaker, I've seen as few as five computer cause this, and when you have 25 odd, its quite a pop when someone unwary tries to reset it

 

[ricicle]

If they are toroidal transformers then the inrush current can sometimes be many times the running current, but not every time. It depends on when abouts on the sine wave that the transformer was energised.

 

[PrenticeBoyofDerry]

Just check all the tranys are wired correctly, load/supply side.
I came across similar problem and one trany was wired in reverse. Worth a check!