Just add the powers so the total power is 240 watts.
because of voltage
Check the package, it will tell you if it can be used for these bulbs. Be careful of compact florescent.
the dimmer should have a rating on it in Watts. dimmers are not suitable for low energy lamps though
All dimmer switches hum. The older they get, the louder the hum. If you have compact florescent bulbs in the fixture, this will cause the switch to hum louder.
Yes, if they replace the switch at the wall.
You cannot use most fluorescent lights with a dimmer. Just about any incandescent bulb WILL work with a dimmer. Occasionally, when a halogen bulb burns out, it will destroy a dimmer switch but halogen bulbs are considered incandescent and other than that little problem they work well with a dimmer.
because of voltage
Check the package, it will tell you if it can be used for these bulbs. Be careful of compact florescent.
Halogen lamps should not be dimmed. At lower voltages the halide is not hot enough and will condense on the glass bulb, darkening it. You will be replacing bulbs all the time.
Could be bad bulbs (double filamented) or bad dimmer switch
Bulbs? Fuses? Relay? Dimmer switch? Headlight switch?
the dimmer should have a rating on it in Watts. dimmers are not suitable for low energy lamps though
All dimmer switches hum. The older they get, the louder the hum. If you have compact florescent bulbs in the fixture, this will cause the switch to hum louder.
Check dimmer switch.
Yes, if they replace the switch at the wall.
Burnt out bulbs? Defective dimmer switch?
I'd be suspicious of the dimmer switch or a wiring connector between the dimmer switch and the headlights.