You didn't say what, if anything was on the circuit. If everything is unplugged from the circuit or disconnected from the circuit and breaker still trips then you have a bad breaker or faulty wiring. If you remove all devices from the circuit and it doesn't trip, you need to find out which device causes the breaker to trip by plugging one device in at a time.
If the disconnect controls a single device like an air conditioner you would have to turn the power off at the main panel and then physically remove the wires connecting the Air Conditioner to the disconnect. Then turn the power back on and see if the disconnect still trips. Again if it does you have a bad breaker or a short somewhere in the box. If it doesn't trip you have a bad motor whose windings are likely shorted or some other condition that is drawing more than 40 Amps.
You have a double pole breaker for 240Volt supply. The maximum current is 15 amp.
Normally older ovens required a AWG #8 wire on a 40 amp breaker. On a modern double oven I would recommend you install AWG #6 on a 50 amp breaker. That way you are safe and will not have to worry about the breaker tripping. It will cost a little more but is worth it in the long run.
No, a breaker is designed to handle the load of only one circuit. Connecting two circuits to one breaker can overload the circuit and potentially lead to electrical hazards such as overheating, tripping the breaker, or causing a fire. Each circuit must have its own dedicated breaker.
A double breaker is a breaker that has 2 switches on it. One of the switches is 20 amps and the other is 30 amps.
No, a double pole 50 amp breaker protects a 240 volt supply at 50 amps. The number that is on the handle of the breaker is the amperage that the breaker will trip at if an overload occurs on the circuit.
Use of a double pole breaker or a single pole breaker depends entirely on the application. If you don't know about the application, contact a qualified electrician in your area.
50 amp breaker wired with AWG # 6 wire.
before the load
Yes!
U.S. 240 VAC breakers are always double pole since they are protecting two legs of the circuit.
can a 20 amp double pole circuit breaker be used for 2 different 120 v circuits using 14 - 2 wire
The term "double pole" usually means a breaker with 2 handles that attaches in the space as a normal single pole breaker. If this is what you mean, no, you cannot. There is no potential, or voltage, between the wire terminals. If by "double pole" you mean what is usually called a 2-pole breaker, which is a breaker with 2 handles that attaches in the space of 2 single pole breakers, then yes, you can use this breaker and 12/2 wire to produce a 220v circuit.