This is the little I do know with regards Halogen Lamps

1.     The voltage of operation is critical. 12volt Halogens are designed to
operate at 11.8 volts. Anything above this voltage dramatically reduces the
life of the bulb.

2. Electronic Regulators tend to be better than transformers for maintaining
the voltage output. But there are poor electronic Regulators and good
transformers.
I should say that in the UK we now operate at the nominal European Voltage
of 230 volts but our voltage continues to be held at the upper end of the
voltage range i.e. 240 volts so a transformer with a 11.8 volt output with
an input of 230 volts is actually running the bulbs at 12.3 volts. I would
need to hunt for the graphs but trust me this significantly reduces the life
of the bulb.

3. If you have to use a transformer (easier to dim) Do not put multiple
bulbs on one transformer, One Transformer - One Bulb. Why? With Multiple
bulbs on one transformer, when one bulb blows, the output voltage of the
transformer rises, accelerating the demise of of the next weakest bulb,
which causes the voltage to rise further.........

4. All incandescent lamps last longer if soft started. The main failure mode
is the high inrush current causing a weakened element to fuse.

Regards

Chris

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