Halogen Bulbs - Flashing problem

[MartinG1971]

Just fitted a new halogen light fitting in my dining room. It consists of a built in transformer, with four 20W halogen bulbs. Decided that this was too bright, so replaced all four bulbs with 5W. Light level is now about right, when I switch on but after 20 seconds or so, all four bulbs start flashing.

I've put the 20W bulbs back in the light, and it works fine but I'm puzzled as to why this happened. Would the same thing happen if I replaced these bulbs with 10W?

BTW: I'm loathe to fit a dimmer switch, as I'm worried about them buzzing. Any suggestions?

 

[Steve]

I'd be loathe to fit a dimmer switch - until i know the transformer is compatible with such a phase-cutting device.

The transformer is probably designed for a power range like 50-100w. You had 20w on it - it was under-loaded, and wouldn't work properly.

Check with the manufacturer if the light is dimmable, and whether you need a leading-edge or trailing-edge dimmer.

 

[bobt]

You can buy dimmer switches that are designed for dimming Low voltage halogen lighting. They don't buzz.

 

[MartinG1971]

I'd be loathe to fit a dimmer switch - until i know the transformer is compatible with such a phase-cutting device.

The transformer is probably designed for a power range like 50-100w. You had 20w on it - it was under-loaded, and wouldn't work properly.

Check with the manufacturer if the light is dimmable, and whether you need a leading-edge or trailing-edge dimmer.

Thanks for the quick reply. The instructions stated that the lights were suitable for use with a dimmer switch, so i guess I'll either try using a set of 10W bulbs or try a dimmer switch.

Still puzzled by the lights though - if the transformer was running at too low a current, the problem should exhibit itself straightaway, right? The bulbs worked ok for between 20 seconds and about a minute before starting to flash. Any halogen bulb experts out there ?

 

[Lectrician]

This is common of an electronic transformer - it will run for a brief period of time, and then flash on and off.

This will occur to all lamp loads - not just halogen lamps!

 

[MartinG1971]

Thanks a lot for the info guys. Every day's a school day!