Do you need a voltage regulator if hook up 12 volt light to 24 system?

Yes, you will need a voltage regulator to hook up a 12-volt light to a 24-volt system. The voltage regulator will reduce the voltage from 24 volts to 12 volts, which is what the light is designed for. Without a voltage regulator, the light will receive too much voltage and will likely be damaged.

It would help if you also wired the light in series with a resistor. The resistor will help protect the light from damage in case of a power surge. The resistor value needed will depend on the specific light you are using.

When working with electrical systems, it is essential to take precautions against shock. Make sure that the power is off before you start working on the light. Also, ensure that you are using the correct tools and equipment.