Tandem Breaker is in half-off position. Unable to reset

Question

I recently bought a condo (2002 construction) and have no experience with electric systems. So please bear with me if I am using incorrect terms.

A few days ago, the plug point where the water kettle was connected stopped working. On the opposite wall of the kitchen, the microwave also stopped working. Both the kettle and microwave were connected to the lower plug points in the outlet. When this happened, I checked the circuit breaker box and only one half of the tandem breakers (circled in red) was in a kind of off position. (I say "kind of off" because the yellow circled breaker is in a "full off" position, but the red ones are not moving at all.)

When half of the red circled breaker tripped, the lower half of outlets stopped working. I switched the appliances to the upper half. (Stupid thing to do in hindsight). Now the top half of the outlets also tripped and both halves of the red circled breaker are stuck in this position. I am not able to reset them. I have removed all appliances from the two outlets it was powering.

1) Can someone please help me understand what is the problem? Like why did half the tandem breaker trip half way.
2) How do I diagnose the problem and what do I need to do to fix this? (I am handy with fixing electronics, but have never done anything with electric appliances)
3) What is this half tripped position called? I am not sure what to look for.

I would've gotten an electrician to look at, but I cannot have anyone come home till the COVID situation is done... my immuno-compromised mom stays with me.

Thank you for your time!

Breaker box - Red circled tripped breaker, yellow circled normal breaker switched off position

One of the two Outlets that tripped

Answer 1

First, unplug anything connected to the tripped circuit. Then, try swinging the breakers all the way to the "off" position before you try moving them back to "on".

Sounds like something that you had plugged in is causing a short circuit. You might be able to test that with a continuity tester or a multimeter, if you have one. Look for an appliance with a closed circuit or very low resistance between the 2 prongs on the plug. If you plug them back in, be prepared for the breaker to trip again and possibly a bit of electrical arcing. Probably not a good idea to test things this way, but some folks might be tempted to try.

Also, if you have any GFCI outlets, make sure that those are not tripped too. These are the kind you usually see in the bathroom with a "TEST" and "RESET" switch. Pushing the "TEST" firmly should make a snapping noise and turn off power to that outlet. Firmly pressing the "RESET" switch will turn the outlet back on.

The outlet in the picture you posted should probably be a GFCI because of how close it is to the sink. It might be connected to a GFCI breaker, or wired with another GFCI on the same circuit that protects both outlets. I'm not sure what the details of the NEC have to say about that, but someone will probably be along that will be able to tell if this is up to code or not.

Regarding the last question (and not trying to be cheeky here... well, not too cheeky...) but I think this condition is just called "tripped" :)

Answer 2

It is tripped

The halfway position is the normal "tripped" position.

For more about what the breakers are generally, here.

To reset it, move it all the way to the "off" position, and then back to the "On" position. Don't make a habit of that. Whatever you're doing to overload the breaker, stop doing that :)

Adapting from Euro power

You have 240V power on that side of the pond. Here, we have 240V, however we center-split it (just like UK does on construction sites) giving us two "sides" of 120V. We use that for small appliances. Unfortunately that includes kitchen appliances.

Now, let's have a word about US and EU appliances, particularly heat appliances. In the EU (checks calendar, after Jan 31, yup) and Britain, appliances just use as much energy as they need for their job. In the US, appliances are limited to 1500 watts, which is not really enough for a lot of jobs by EU standards. However your breakers have an 1800W (120V x 15A) capacity, so it means you can't run 2 of them at once regardless!

So you either tripped it from running a Euro appliance or from running 2 things at once on the same half-circuit.

Two half-circuits

Remember how I said America splits the 240V to make 120V "legs"? That circuit is a "Multi-wire branch circuit" which uses both "legs" to provide two half-circuits of 120V and 15 amps each. Some of your receptacles (and possibly microwave) are on one half-circuit, and something else is on the other half-circuit. If you can figure out which ones (an electrician can easily mark this for you), you can arrange your appliances so you have one big heat appliance on each one, and then you won't trip!

Answer 3

The 1/2 off position shows that the breaker tripped. It sounds like your house is wired like I used to wire. A multi wire branch circuit with the top receptacle on 1 breaker and the bottom on another. To reset the breakers pull them completely to the off position. Then pull them to the on position. If one of them clicks and returns to the mid position the over current may be due to a short in the wires. I have not had issues with square D resetting when properly cycled to off then on positions.