Stop using unsafe equipment
If the heater trips power, leaks, smells burnt or behaves unusually, stop using it and arrange proper checking. Do not keep resetting the breaker repeatedly.
Useful details to send
Send photos of the heater, switch, model label if visible and the area around it. Mention whether the trip happens immediately or after the heater runs for a while.
Licensing may matter
Water heater work can involve both electrical and plumbing scope. Certain work in Singapore may require licensed professionals.
Official references
Use these sources for current Singapore licensing or renovation guidance before treating a repair article as final advice.