Lighting transformer help!

[LankyWill]

Clients bought some track lighting(catenary wire type with anchors etc) to install in three bedrooms upstairs. All rooms are on the same B6 MCB. Each comes with 4 lights to screw on to the 12v wire track.

Transformer is 210VA 230v-12v step down

Calcs-
230v/210VA = 1.1A per track setup, 4x50w halogens will be fine per setup.

The transformer is rated at 15A and has an inline fuse protecting it. I am assuming the transformer isnt actually pulling 15A continuously its just a protective measure?

Lastly the transformer keeps tripping the mcb if switched on and off in succession, i think this down to inrush current and will be upgrading to a D6 MCB. Can anyone confirm my calcs and my theory on the 15A scenerio.

Cheers Lanky

 

[Octopus]

D6?

What is the Zs? I would try a type C or depending on cable size a 10A type C

 

[LankyWill]

zs comes in at 1.45, C6 would still be too sensitive if all three are turned on (kids bedroom). doesn't help with the fact they're are loads of halogens on the same circuit.

 

[Octopus]

zs comes in at 1.45, C6 would still be too sensitive if all three are turned on (kids bedroom). doesn't help with the fact they're are loads of halogens on the same circuit.

The transformers will have high start up currents so unless they are switched on at exactly the same time.

What size is the cable?

 

[LankyWill]

1mm switch wire and 1.5mm feed. im reluctant to go to a c10 as the runs are quite long and pass through insulation throughout.

 

[Leesparkykent]

Had the same thing recently with the same sort of light. Ended up on a C type 6A and was happy days.

 

[Lucien Nunes]

You can't tell the exact running current because you don't know the power factor but fully loaded it would be > 210/230=0.9A (not sure why you wrote 230/210 but 1.1-1.3A is not a bad estimate allowing for pf). The 15A internal breaker is on the output side - with 200W on 12V the output current is 200/12= 16.6A but they will be partially using up the fusing factor of the MCB.

The inrush on these is notoriously high. A C6 might hold, IIRC I had some on C6's and some on C10s in our old offices. Problem I had was too many transformers on each switch, IIRC I replaced some of them with alternative types with lower inrush.

 

[SJD]

I don't suppose this is too helpful, but why are people still installing 12V halogen lighting, ... can't this be done with LED technology now?

 

[LankyWill]

Its the scenario where looks come before practicality sadly, id rather use a more effective electronic transformer but these are not decorative. I would have used LED's throughout but clients adamant. Thanks for the help lads appreciated, C6 it is.