Ok What is happening:
Light bulbs of that type are what is called a Positive Coefficient Resistor.
What this means:
Resistor.. The glowing wirem, electronically that is a resistor. (A device that impedes the flow of electrons) Like a flow restriction device in a shower head.
Positive (Temperature) Coefficient. Means the hotter it gets.... The higher the resistance.
Cold it has a very low resistance.. but as it heat up, the resistance goes up, way way way up..
In fact I use a light bulb as a fuse her ehe motor home.. Cold, the normal draw on that circuit is not enough to even dimly light the lamp. but if there is a short, Light limits the current flow to a level that won't burn down the house.
How to tell the wattage of the bulb.
Plug it in, measure current.
