What causes a circuit breaker to be warm or hot?
Breakers which are overly hot, may be damaged or defective and should be replaced. Some heat is not uncommon.
Also, if a breaker is hot it may be an indication that the circuit is overloaded and that this overloading condition is causing the breaker to be hot. In either case, an electrician should be consulted.
Poor connections often create heat. When they’re not is not a full and proper connection, then the amount of resistance is higher. The higher the resistance, the more the heat. The connection issue may be that the breaker is loose and not firmly and fully connected or secured to the busbars or that the wiring connected to the breaker is not fully connected.
Failure to replace the breaker or the overloading of the circuit may result in total failure of the breaker or a fire.
The metal panel is hot
If the metal panel is hot to the touch, then it is wise to have an electrician review the panel, for there may be a defective breaker that needs replacing or some other cause that is creating the heat.
Who to consult? An electrician.
Electricians can easily determine if a warm or hot breaker is fine or if a new one should be put in.