I have recently installed an IP rated LV external light in the soffit over my front door. Using a web site lighting circuit diagram as guidance I wired it with 2.5mm cable to a transformer which in turn is wired via 1.00mm cable to a 4-way junction box which is wired to a switch and through a fused connection unit(3AMP fuse) back to the existing lighting circuit actually the loop-in connections to an existing hall light which is retained. However the LV light will not work when its switch is turned on. I have checked all connections are properly carried out in accordance with the web diagram but nothing is happening. Could the transformer be faulty? although I have tried another of the same type, but still no joy!.
Sorry this needs a meter to test and guessing what may be wrong is unlikely to be helpful. Also 230 volt is "Low Voltage" and 12 volt used in many spot lights is "Extra Low Voltage" which comes in two flavors "Functional" and "Separated" so it will be SELV or FELV and the connections on the bulbs are normally two little pins. LV (230 volt) with spot lights is normally called GU10 and is a bayonet connection.
If you have used a LV bulb on a transformer it will not work. I expect it is only the terms you have wrong but thought better to check.
I purchased the light fitting from an on-line company as a package ie light fitting with 20/60VA electronic transformer and 50w halogen lamp with two pin connection to ceramic connection in light fitting. I presumed this was OK to install.
As I mentioned before I took the new supply of the mains lighting circuit at an existing hall light where the earth and live (red) is continuous but the neutrals are split to allow the existing light to be connected.(The switch wiring is not located at this point)My new supply red live I propose to connect to existing red live, and neutral to neutral, in turn this connects to a fused connection unit(3amp) the fcu that I purchased has live and neutral (imput) which I will connect my new supply from the lighting circuit and exiting live and neutral from the output side.As I described before this connects to a switch and in turn to a 4-way junction terminal to the transformer and then the outside ELV light.
As I previously said the light does not work when new switch is on!!