Circuit breaker tripping, or non functioning outlet. The neutral and hot can be reversed, or an open ground, and you will have no symptoms. This can only be detected with a circuit tester you plug in to check the wiring.
A series circuit/
If it is a properly wired circuit (according to code) in the home, the breaker for that circuit will trip deenergizing the shorted circuit. If it is not properly wired, it could get hot and start a fire and possibly burn down the home.
An Amp Meter
A dedicated 20 Amp circuit wired with 12/2 wiring an a 20 amp breaker.
Generally in a parallel circuit
The ignition switch is wired incorrectly, is damaged,or a wire is damaged and contacting the starter relay circuit .
You have wired it incorrectly.
A series circuit/
They are wired in series.
A parallel circuit
If it is a properly wired circuit (according to code) in the home, the breaker for that circuit will trip deenergizing the shorted circuit. If it is not properly wired, it could get hot and start a fire and possibly burn down the home.
Stuck relay or the starter is wired incorrectly.
Short in wires or wired incorrectly.
Thermostat turned all the way up,thermostat defective, thermostat wired incorrectly, heating unit wired incorrectly, fan or heat relay stuck closed are the things I would look at to start.
the paralel
I you wired a light bulb in to the same circuit you have the possibility of over loading the circuit but other than that it would just be brighter.
There are many types of electrical circuits and each one is wired differently. Without knowing the specific circuit that needs to be wired, this question can not be answered.