Circuit breaker tripping

[Hall]

I'll preface this by saying I am comfortable doing basic electrical work including adding circuits and breakers to a breaker box. If an electrician is needed, so be it, but just seeing if there's something common to look for before calling in pros.

At my son's house, what's happening is if they have the stovetop (220v) on and use their Keurig, the breaker that the Keurig is on trips. They can use the Keurig any other time with no issues. The stove's breaker does not trip (ever). Does this sound like a shared neutral ? If so, my understanding this is acceptable if the breakers are on separate legs. In his case, they are on the same leg, making me suspect a shared neutral even more.

Ideas ?

 

[bullwinkle]

The neutral shouldn’t go to a breaker, it just goes to the bus bar in the panel (also connected to earth ground).

 

[Warstud]

Yes ... your overloading the circuit . Just use the Keurig on another outlet when using the stovetop

 

[CDX825]

Thats a weird one. A 240 volt circuit should have no effect on a 120 volt circuit and vice versa a 120 shouldn't effect a 240. Most 240 volt appliances don't use the neutral for anything unless they have something needing 120 volts like the light in your stove or dryer. The main load is line to line or leg to leg.

I would check the wiring in the breaker panel and at the outlets in question to see if anything is loose.

 

[Cujet]

With something like a well pump, a 240V circuit does not utilize the neutral for anything.

But for other appliances like a stove, there may be a 120V circuit for stove top burners (typically Hot to Neutral) and of course the light bulb. The Oven's burners use a full 240V, and do not employ the neutral. Try each different burner.


A guess:

He has a bad neutral, possibly at the transformer. Check voltages at the Keurig and check voltages on the other leg somewhere else in the house. Use a multimeter, or Kill a Watt. You can even use a UPS with voltage display. If you see a wild voltage differential between the two "legs" the neutral is bad somewhere.

The discrepancy in voltage is related to an unbalanced load with a bad neutral.

Let us know.

 

[dlundblad]

Would a shared neutral cause the breaker to trip?

Are you certain the stove top is 240 and not 120?

 

[Pablo]

I'll preface this by saying I am comfortable doing basic electrical work including adding circuits and breakers to a breaker box. If an electrician is needed, so be it, but just seeing if there's something common to look for before calling in pros.

At my son's house, what's happening is if they have the stovetop (220v) on and use their Keurig, the breaker that the Keurig is on trips. They can use the Keurig any other time with no issues. The stove's breaker does not trip (ever). Does this sound like a shared neutral ? If so, my understanding this is acceptable if the breakers are on separate legs. In his case, they are on the same leg, making me suspect a shared neutral even more.

Ideas ?

Stove top? Like in a counter?

Does the stovetop have more supply to it than the 240v?

It’s possible there is an imbalance but quite odd

Are you sure the breaker is just a simple single pole breaker not a GFCI combo?

 

[Hall]

Yes ... your overloading the circuit

Different circuits

 

[Pablo]

And this is a 20A breaker with 12ga wire?

 

[Hall]

But for other appliances like a stove, there may be a 120V circuit for stove top burners

Are you certain the stove top is 240 and not 120?

I didn't realize the burners could be 120v. I knew the stove could split the power, i.e. the light bulb could run off a single hot leg at 120v or the panel (probably stepped down from 120v to 5v vs 220v to 5v).

A guess:

He has a bad neutral

I was thinking shared neutral but at least I was on the right path that it was neutral related (maybe).

I would check the wiring in the breaker panel and at the outlets in question to see if anything is loose.

He's not comfortable doing this type of work so it will have to wait until I am able to get there and presuming I remember and bring my tools.

 

[Nukeman7]

Might be a defective breaker on the Keurig circuit. If you are comfortable changing out breakers, just swap it with an identical breaker (20 Amp?) from a different circuit in the box. Be sure to identify all outlets on both circuits before swapping the breakers so you can trace and diagnose the issue.

 

[Donald]

I think a carful look over of the circuit breaker box, including the ground and neutral bus is warranted.

Something is not right.

Are they wired to the main circuit breaker box or a branch box?

 

[Hall]

Might be a defective breaker on the Keurig circuit.

It doesn't trip if the stove isn't on though.

 

[football]

I believe the code calls for AFCI or GFCI breakers on almost all circuits on newer homes. These are notorious for tripping.

My son’s room kept tripping these new breakers every day. I went back to the basics, took all the outlets out and saw that they were using the back stabs and then continuously running down the line from outlet to outlet.

I added pigtails to every outlet and got rid of the back stabs and used the side connections under the screws. No more tripped breakers.

Pull the outlet out and make sure the connections are tight. Make sure the connections on the breaker are tight. Make sure all the neutrals are tight in the breaker box.

Swap the breaker with another one in the panel to see if the breaker has gone bad.

 

[JHZR2]

Let’s make sure we have this straight:

- The cooktop is on a 220v circuit - we are sure if this? If we open the breaker the cooktop doesn’t work?
- Is there a stove, and does the stove have a separate breaker?
- The Keurig works on other circuits when the cooktop is working?
- The Keurig never blows the circuit when the cooktop is off?
- How old is the home?


You explained essentially that there may be a MWBC, but if it was associated with a 220v range AND an outlet, then the cooktop breaker would open. I take it that it’s a different breaker that opens.

If the cooktop doesn’t really use the 120 breaker, and this is an old house where they somehow made a separately wired 220 from two 120v hot legs, then one may be overloaded. The two poles are not mechanically connected on the breaker, which is bad, and one gets overloaded. That wouldn’t explain the cooktop still working, unless it stays illuminated and maybe runs some functions due to 120v still being present.


To me, job #1 is to determine if the cooktop is truly fed by, and functional solely from a 220v breaker. If it is, be it entirely running off if 220, or via service that gives it a neutral, then the situation is different than if it is believed that it is fed by a two pole breaker, but really isn’t.

I suspect it was retrofit from two 120v breakers, the 220v breaker is from something else, and the Keurig overloads half the circuit…

 

[JHZR2]

I believe the code calls for AFCI or GFCI breakers on almost all circuits on newer homes. These are notorious for tripping.

My son’s room kept tripping these new breakers every day. I went back to the basics, took all the outlets out and saw that they were using the back stabs and then continuously running down the line from outlet to outlet.

I added pigtails to every outlet and got rid of the back stabs and used the side connections under the screws. No more tripped breakers.

Pull the outlet out and make sure the connections are tight. Make sure the connections on the breaker are tight. Make sure all the neutrals are tight in the breaker box.

Swap the breaker with another one in the panel to see if the breaker has gone bad.

I’m not sure that these are necessary for 220v hardwired circuits. But they likely are for the kitchen 20a circuits (two per code as I recall).

Back stab or not, they’ll also trip if noisy loads create funny characteristics. Ive seen it with fluorescent lights and motors. So you’re onto something… if the cooktop is some cheap thing thst isn’t designed well, maybe an induction design that has a funny power quality, then it may reflect some harmonics back that throw off the other circuit when the Keurig with its resistive load comes on. Exactly why I’m not 100%. Maybe @MVAR has some thoughts on those interactions…

 

[dlundblad]

A shared neutral should be easy to find. A #12 120v circuit and a presumably #6 wire on a 240v circuit is quite obvious.

Where are the breakers located in relation to each other in the panel? If they are close, maybe the 2 pole 50 amp for the stove is making the single pole warm and causing it to trip. Stove top isn’t a large load though. Like I said above, Make certain the stove top and oven are together and that the stovetop simply isn’t 120v.

A meter with an amp clamp would be handy. Check amps of the hot wire at the breaker on the coffee maker circuit while it’s on. Have someone turn on the stove and see if it goes up. You can also do this with the neutrals, but simply sharing neutral wires shouldn’t cause the breaker to trip. It’ll just make the wires hot and eventually cause a fire.

 

[SHOZ]

Make sure ell the terminal screws are tight.

 

[dlundblad]

Also, check voltage on both main lugs at the panel with everything off, then with the coffee maker on, then with the coffee maker and stovetop on. Is there a voltage drop issue?

Try swapping breakers for the coffee maker.

 

[MVAR]

With something like a well pump, a 240V circuit does not utilize the neutral for anything.

But for other appliances like a stove, there may be a 120V circuit for stove top burners (typically Hot to Neutral) and of course the light bulb. The Oven's burners use a full 240V, and do not employ the neutral. Try each different burner.


A guess:

He has a bad neutral, possibly at the transformer. Check voltages at the Keurig and check voltages on the other leg somewhere else in the house. Use a multimeter, or Kill a Watt. You can even use a UPS with voltage display. If you see a wild voltage differential between the two "legs" the neutral is bad somewhere.

The discrepancy in voltage is related to an unbalanced load with a bad neutral.

Let us know.

This is good advice to start your troubleshooting.

For something very easy, after above has been verified. I’d be curious if the 120v circuit the coffee maker is on is supplied by an arc suppressing breaker(they usually have gfci outlets & a green sticker in the breaker). I’d also be curious if that 120v breaker is the closest breaker to the 240v breaker supplying the oven. Those arc suppressing breakers are very sensitive to harmonics & heat. If the breaker next to it on the bus is vibrating or heavily loaded creating additional heat, the arc breaker will become too sensitive. If there’s room to swap two 120v breakers on the bus, just swap their positions & see if the problem goes away.

The best idea is to follow @Cujet advice first. Once neutral is verified good, if you’re left scratching your head, swap the position of the 120v breaker if it’s an arc suppression breaker. I’ve chased my tail for a day or two only to have that work & I ended up replacing a vibrating breaker & just cleaning all connections/terminals/busses while I was in there.