Mercury Vapor lamp glass broke so do not know the wattage. Numbers on metal base are: JHMAMJ - 4A80AD. What lamp do I need to replace the broken one?
The most common answer will show up in the ballast area if the label or marking is not " erased " or gone and most common dusk to dawn MV verison is typically 175 watts ( USA / Canada side ) however there is one gotcha is that you can get the MV lamp but not the ballast anymore.
So if the ballast is shot then you will go with Metal Halide or Super Compat flourscenct lamp.
The answer will be based on NEC ( National Electrical code ) or CEC ( Cananda Electrical code ) or ECF ( Electrique Code France )