Wire gauge for light fixure

[blueman]

I need to rewire an "antique" brass wall light fixture that has a very narrow throat for threading the wires along a complicated floral pattern.

The fixture has 3 candelablra bulbs. I plan to use either a maximum of 25 or 40 watts.

For each of the respective wattages, what is the thinnest guage wire I can use per code? (note the lights are hardwired into the wall)

- Case A: assume I use separate wires for each of the bulbs (at 25 or 40 Watts)

- Case B: assume I use a single feeder wire thus carrying either 75 or 120 Watts respectively

Is there a special thin insulation wire that is made for threading in tight spaces?

Thanks

[gfretwell]

18 guage is the smallest fixture wire you can use on a 15a circuit