Vacuum is tripping breaker on a different circuit

Question

Why would a breaker trip when vacuuming? The kicker is the vacuum still works, because it is plugged in on a different circuit. Breaker being trip is the family room breaker. Which had 4 can lights, OLED TV, ring alarm, cable box, security nvr, light hub, and Ethernet switch. Not all are always on. Breaker tripping is a GAFCI 15 amp Siemens breaker. Breaker that vacuum is plugged into is either a 15 amp Siemens single pole breaker or 20 amp Siemens single pole breaker. I haven’t changed anything on my breaker panel recently. Breakers are about 9 years old. I do hear a “noise” like a small arc coming from the 20 amp single pole breaker. The fridge is on this breaker. As well as the gas range. Dishwasher breaker has some kind of metal thing around the breaker. Family room lights have always flickered when vacuuming.

Answer 1

This is a classic Arc Fault situation.

• GAFCI = GFCI and AFCI. Unless something is really, really wrong (mixed neutrals or neutral/ground bonded where it shouldn't be, both of which would trip the GFCI immediately and consistently) this is not GFCI. Which means it is AFCI - Arc Fault Circuit Interrupter. There should be some sort of light/code on the breaker to tell you that it is specifically an arc fault, but I'm pretty sure of it.
• I do hear a "noise" like a small arc coming from the 20 amp single pole breaker. - That may be real or imagined, as an AFCI can detect arcs that are invisible to the naked eye and inaudible to the human ear. But it does fit the basic problem.
• Family room lights have always flickered when vacuuming. - That is also indicative of either arcing or a very high power draw from the vacuum cleaner causing power fluctuations.

All of this put together points to the vacuum cleaner producing sufficient power line noise that it is interpreted as an arc fault on a nearby circuit. Unlike GFCI which measures current (or really the balance in current on two or three wires), an AFCI is "listening" for noise, which can be induced or conducted from nearby wires.

The GAFCI may be a little oversensitive. Or the vacuum cleaner may be having serious problems and need to be replaced. My guess is somewhere in between or a little of each. Vacuum cleaners tend to have big motors because you want lots of power! They tend to have electrically noisy motors because you use it for a few minutes so who cares if the lights blink and the radio crackles while it runs. They also tend to be audibly noisy as well, but that is not directly related to this problem, except in the sense that you can make a motor: powerful, high-quality (minimize electrical noise and audible noise) or inexpensive - pick 2 out of 3. Most people don't know anything about electrical noise. They may know about audible noise (measured in decibels) but while low noise is a selling feature on a bathroom or kitchen fan, it doesn't really matter much for a vacuum cleaner. So vacuum cleaners are sold based on basic features (canister vs. upright, how many attachments, etc.), power (more is better) and price (lower is better).

You may want to check with the Siemens to find out if there are any adjustments or newer breakers (warning: these are expensive breakers) or if they have any other suggestions. Other than that, live with occasional trips or get a new vacuum cleaner and hope it does better.

Answer 2

If you've ever hooked up speakers with the amplifier power turned on and heard the crinkle-crunch sound, you've experienced an arc fault. You know both what it is and what it "sounds like" when the electromagnetic wave is converted to sound waves (which convert very well; it's what speakers do).

You probably know digital signal processing is pretty good these days. Well, that's what an AFCI breaker is. It's doing DSP to recognize that crinkle-crunch "sound" on the wires.

Most arc faults are "series arc faults" meaning the arcing is inline in the wires due to a loose or faulty connection. It is only there if a load is there. And the bigger the load, the more likely and detectable the arc fault is.

However, it's unavoidable that an AFCI can "hear" arcing on the LINE (input) side of the breaker. Thus, AFCIs have the weird (but still helpful) tendency to trip from arc faults on other circuits. So an arcing fault in that circuit is causing the ACFI to trip. Weird, but true.

You can dismiss this as "Aww, vacuum cleaners trip AFCIs all the time, let's just call it that and sleep soundly". Well maybe. But it could also be a genuine arcing fault on the circuit.