Breaker Trips when I On the Garage Lights

My house is 10 years old. No problems with this circuit, or any others, until a couple weeks back. Before getting a Sam Adams out of the garage fridge, I turned the fluorescent lights on. I heard breaker # 12 trip; no lights in garage.


There are four light fixtures in the garage. Each has two, 4’ long , 6500k, 32 watt T8 bulbs. The other electrical loads on circuit #12 were off, as they normally are. I do not remember if the refridgerator was running or not. I do not suspect any water leakage into a circuit; it had been dry many days before.

I reset the breaker and everything works normally for a couple weeks.

Last night, same thing happened, and I still didn’t hear if the garage refrigerator was running or not. No rain in many days, so no water leakage issues suspected.
I hate intermittent problems!

I plan on turning off the breaker and checking the light switch and it’s connections in just a few minutes after I eat lunch. I’ll also replace any tubes that are not working or are partially dim.

My next suspect is probably the breaker, but maybe I should look in all the devices/junction boxes on the circuit first. Any advice?

I replaced two fluorescent tubes. One would not light and the other was very, very dim.

After opening up the switch, the switch, connections, and wires were unremarkable.

Next time I run out, I’ll pick up a replacement switch to have on hand.

Did I tell you, I hate intermittent problems!

Disclaimer: While I started wiring houses when I was 14 years old, I spent most of my career in the heavy industrial field.
However I am happy to offer some tips based on basic trouble shooting practice.
In order of possibility:

  1. Failing light switch. (Contacts are arcing slightly when closed)
  2. Bad tomb-stone socket in a fixture.
  3. Failing breaker.

  1. How is the feel and action of the light switch? Is it a nice crisp action, or is the action soft and indeterminate?
    The switch may be failing and arcing internally.
    Remove the switch from the circuit and test the continuity with a multi meter.
    Turn the switch off and on and repeat several times.
    The reading should be zero Ohms.
    A bad reading, replace the switch.
    A good reading is not conclusive.
    Compare the physical action and feel with an identical good switch.

  2. Another possibility is an arcing tomb-stone socket in one of the fixtures.
    This will probably be visually apparent by discolouring of a socket.
    Each end of the lamps may have a small element that completes the 120 Volt AC feed to the ballast. Unlikely but there may be an internal arcing fault in a tube. Reversing or replacing the tube should fix this.
    This is a lower probability as one fixture may not draw enough current to trip the AFCI circuit of the breaker.

  3. Failing breaker.
    Locate a circuit with a similar load and switch the circuits between the breakers. See if the issue follows the breaker.
    Good luck.

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The switch had a nice crisp action. I must have turned it on and off several dozen times while troubleshooting. No trip. The only thing that I took note of was when I pushed and pulled the red wire into/out of the screw-less connector, the wire did not feel like it slipped in and out of the clasp(?), but the whole clasp gave way a little so it appeared the red wire went in and out. Of course this all happened internally, so I’m going by feel and what I could see externally. That’s why I’m going to pick up a new, white, 15A, single switch.

I hate those push-in connections.
I have almost zero experience with them as I always used the screw connection and ignored the push-in feature.
I assume that this is the connection to the switch?
It may be well to check the connections in any Junction Boxes in the circuit.

Yes, all the connections use the push-in connectors. I’ll replace the switch when I get a new one.

If this persists after a new switch, and I have to drop the light fixtures to see the connections, I may look at some LED fixtures to replace them with. Much less power and longer life are appealing. I have no idea of the cost right now though.

Okay, $2.99, 20A Leviton Plus + switch installed. IMO, I went up in quality and duty from the original contractor grade switch.

Now it’s a waiting game for the next trip, or not!

those are arc fault circuit interrupters. I have never used or installed one yet but I have heard of numerous problems with them. They are supposed to trip if they detect a loose connection that causes any sparking, so many sources of electrical noise on the line can can cause a trip. The sensor circuits in the breaker may be bad.

I heard years ago, that one should not use a GFCI on an older fridge. Maybe that is the issue, or not.
But then again it could be the lights.

It has been trouble free for 3 years. The fridge plugs into a GFCI receptacle which is wired into the AFCI breaker.

No problem since changing the garage light switch. :crossed_fingers:

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So the change in the light switch happened before this started. Light switch’s are not that hard to change.

No, the original light switch was 10 years old. Twice when I turned on the original light switch to the garage lights, the AFCI tripped. The second trip was a few weeks to a month after the first trip. Theorising the light switch was a likely cause and it being so cheap and easy to change, I changed the light switch 3 days ago.

Now, it’s a wait and see game.

I’ve been meaning to look into getting those LED fixtures for my garage too. More light for equal power or equal light for less power, either way.

You can try changing to an LED bulb with the fixture you have. I tried some of those in both the 4’ tube type, and the edison base, and they work well.
I even have tried the 4’ tube type that you have to remove the ballist, and it works well.

Really! Thanks. I didn’t know that was possible. I have about 6 more new florescent tubes still in the box. When I go through those, I’ll look into this.

Yea I still have a couple of the old bulbs myself. But that did not stop me from trying the LEDs in a fixture or two.
The T8 fixtures work well.
I had an old one with a bad ballast, and I used the direct 120V wire in for that.

The duration between trip #1 and trip #2 was 2 weeks. The duration between the switch replacement and now with no trip is 16 days. I’m not ready to declare victory yet, but this is a good sign!

No trips in the 4 months since I changed the wall switch. That must’ve been the problem.

1 year and 1 month and no trips from the new switch!

However, AFCI breaker # 12 started randomly tripping Saturday. It would stay on for 3 hours then trip, 2 hours then trip, 1 hour then trip, and finally it started tripping as soon as I on the breaker, which made it much easier to troubleshoot. So, I went through items on the circuit and turned them off and unplugged them. And, then, ah ha, the timer controlling the lights outside the garage is the problem! I turned that off and taped a note over the switch, until I find time to take it apart so I can get the info. needed to order a new one. With it off, the rest of the circuit is happy.

On second thought, why a timer? I changed the outside garage lights to LEDs when we moved in 5 years ago. They don’t cost much to keep lit. A combination exterior light detector and motion detector would mean I never have to adjust the timer again! I need to noodle this over some more. What do you guys have/recommend? More on this later.

I just installed a bunch of integrated color outdoor LED Philips Hue floods and a couple wall fixtures with discrete bulbs. Very cool system but not cheap. I have installed one motion detector to turn lights on to white full intensity for a few minutes then revert to previous state. The individually programmable colors and sequences are neat. Another cool feature of the hub is that you set it to your location and it will automatically track sunrise/sunset through the year to post/pre-empt the diurnal cycle. Probably more than you are looking for for basic light/motion though.