If its a water heater type element its likely 220 but plenty of people on here run them at 110. If you cant figure out what the wattage is, its only like $15 to replace the old one with the one you want.
If you have a VOM (volt-ohm-milliampmeter), you can measure the resistance of the element. If you can verify the voltage rating (maybe the cord is still connected and you can tell by the plug), then you can calculate the wattage by the formula P = V^2/R. That's the voltage squared divided by the resistance.
For 240 volt:
a 5500 watt element would have a resistance of about 10.5 ohms
P = (240)^2/10.5 = 5486.
For 115 volts:
a 1500 watt element would have a resistance of about 9.6 ohms