I have a halogen light fixture that I'm trying to fix/repair... it came from a horse farm. When I climbed up the ladder to measure the voltage of the three prong plug I got 240 volts between the first and second prong... then 110 between the secondand third prong... and then 0 between the third and first prongs is this normal how many volts do these run on?? Thanks

Hello djdjdj

I'm not too sure what you mean with 'three prong plug'.
Halogen lightfittings are made either for low voltage lamps, or for 240 Volt lamps.
And never are these different voltage lamps mixed in a lightfitting : they are all low voltage lamps, or all high voltage lamps.
For a 240 voltage lightfitting there is no transformer or voltage regulator needed. For a low voltage lightfitting there is always a transformer or voltage regulator present.

If with 'three prong plug' you mean the mains connector or some connection block, the different voltages are explained as follows :
Your US electricity system uses neutral as zero Volt with two different hot/live wires of each 120 Volt. The two live wires have 240 Volt between them. And between neutral and earth the voltage is normally nil.

Does that answer your question?

Halogen is a type of lamp (light bulb). Simply asking what voltage a "halogen" lamp is is impossible to answer.

They can be low voltage, 6-12v; or line voltage 120 or 240v. It all depends on the fixture and type of lamp.

Just some additional information :

Depending on the inside mirror small halogeen spots produce different lightbeams.
The filament size is important also : the smaller the filament, the narrower the point of light.
Low voltage lamps have a small filament, but 240 Volt lamps need more space for the filament.
Therefore all halogeen narrow-beam spotlights are always of the low voltage type.
240 Volt halogeen spots are used for general lighting or to flood a specific area (painting).

Hmm... is the "three pronged plug" the photcell for the fixture?. Djdjdj, more info please.