Warning: Arc Faults and Festool

[Michael Rutman]

In my new workshop build out I found that my bandsaw was tripping the breaker whenever a Felder vacuum was plugged in. No other gear, just the Felder, and not on, just plugged in. I was also seeing it with the Kapax but not consistently. The electrician came out, verified that there was no short, the bandsaw peaked at 4 amps and nothing seemed wrong. He suggested it might be the new code for circuit breakers now detect arc faults (AFCI).

A little googling and I found one other person with the same problem and they verified that some Felder equipment will trip the breaker when other equipment is turned on. The electrician says he sees this problem with smart devices. The AFCI interprets the devices normal usage as an arc fault, and as the requirement for AFCI are new, a lot of devices haven't been updated to not trip them. He spent an hour verifying there was nothing wrong with the circuit when the Felder was not plugged in.

The Felder plugged into that circuit without anything else running works fine.

I am not an electrician, just thought I'd share my experience so anyone doing a new build out is aware it might happen to them.

[Jim Becker]

Arc Fault are important for safety in many situations, but indeed can be problematic for certain uses...there are many kinds of devices that can falsely trigger them. I remember another discussion about this awhile back, actually. I wouldn't use them in a shop situation, especially for dedicated machine circuits. In some cases, that might mean a bit of dancing if an inspector insists on them to pass the job. When the final inspection occurs also can impact that. Although AFCI isn't require here universally as we are not yet under the NEC 2020 version, the fact that my new shop electrical received final inspection with just the panel and one working GFCI outlet too the whole matter off the table. But it's a separate building not attached to our home. In the end, everything is local when it comes to electrical code enforcement.

[Rod Sheridan]

Michael, was that a Felder or Festool vacuum?

Regards, Rod.

[Maurice Mcmurry]

Arc faults were new to me when working in Durham NC. We were required to install them on any new circuit. A few of my tools would trip several breakers at once. After extensive trouble shooting the power company finally found a loose neutral connection at the pole. Once that was corrected the problem stoped.

[Tom M King]

I wonder how many things have been saved by an arc fault breaker.

[Jim Becker]

I wonder how many things have been saved by an arc fault breaker.
The original intention was apparently to guard against folks (especially kids) getting fried when "ever popular" extension cords were used improperly and wore through. That's one reason why the mandates started in sleeping spaces, to my understanding.

[Aaron Inami]

How about a power strip attached to a power strip attached to a power strip all with about 15 devices plugged in! lol.

[Jim Becker]

How about a power strip attached to a power strip attached to a power strip all with about 15 devices plugged in! lol.
Certainly "fun" to troubleshoot which device is being ornery with your arc fault breaker. :) :D

[Michael Rutman]

Arrrrg, finger memory, Festool not Felder.

[Rollie Meyers]

The original intention was apparently to guard against folks (especially kids) getting fried when "ever popular" extension cords were used improperly and wore through. That's one reason why the mandates started in sleeping spaces, to my understanding.


I wonder how many things have been saved by an arc fault breaker.

Not able to protect extension cords & the whole process to get them included into code was filled with deceit, making the users the beta test, unlike GFCI's,which are proven to work, nobody can prove AFCI's do every brand of them having different proprietary circuitry, I call AFCI's snake oil.

[Aaron Inami]

Okay, I have a question here. It seems that arc-fault AFCI breakers will trip sometimes on high current motors from woodworking machines. Do the GFCI breakers/outlets have the same problem?

[Bill Howatt]

I don't think GFCI have the same problems although there are reports they can be a problem when used with electronic single to 3 phase converters like VFDs driving motors.
I hadn't heard about high-current motors be categorized as a AFCI problem but any motor with brushes can be due to their inherent arcing and sparking especially when older.

[Rod Sheridan]

Okay, I have a question here. It seems that arc-fault AFCI breakers will trip sometimes on high current motors from woodworking machines. Do the GFCI breakers/outlets have the same problem?

They GFCI’s can trip when starting or stopping inductive loads, induction motors can trip them during opening of the centrifugal switch due to current asymmetry.

AFCI’s can trip due to arcing in wound rotor motors or centrifugal switch opening in induction motors.

Regards, Rod

[Rod Sheridan]

Arrrrg, finger memory, Festool not Felder.

Makes sense now, thanks for the correction

Regards, Rod

[Rod Sheridan]

Arrrrg, finger memory, Festool not Felder.

Makes sense now, thanks for the correction

Regards, Rod

[Bill Dufour]

I put gfci breakers in my shop panel. Did not work on VFD for drill press. Did not work on simple air compressor. How to use a regular breaker.
Bill D

[Michael Rutman]

I want to be clear, the AFCI is not tripping on the Festool being started, just plugged in.

[Monte Milanuk]

Just curious... anyone here familiar with *how* these breakers are 'detecting' the supposed arc fault?

Most of my experience with arc fault tech has been more in the realm of big-boy toys i.e. metal-clad switchgear, substations, etc. where they use a combination of pressure sensors, polarized light filters and other current sensing devices. Breakers in a residential panel... seem like that'd be jamming about 10 pounds of... stuff... in a 5 pound bag, and work about as well as expected.

[Rod Sheridan]

I want to be clear, the AFCI is not tripping on the Festool being started, just plugged in.

Does it trip with the Festool in the off position?

Does your vac have Bluetooth?

Regards, Rod

[Rod Sheridan]

Hi Monty, the AFCI breakers look for the frequencies generated by an arc and open the circuit

Regards, Rod

[Monte Milanuk]

Hi Monty, the AFCI breakers look for the frequencies generated by an arc and open the circuit.

Must be quite the schema to pull that kind of fingerprint out of all the crap and harmonics generated by modern electronic power supplies. Neat!

[Michael Rutman]

Kapax was definitely off when it happened. I can't remember if the vacuum was ever off vs on auto. I doubt it was off as when it is on that side of the workshop it's usually has either the Kapax or a sander plugged in.

No bluetooth.

Electrician said he has seen it a lot with "smart" devices. He suspects that there is a constant current drain to run the smarts and that current is "leaking". He doesn't really know but googling for it seems to confirm that nuisance tripping is common.

[Michael Burnside]

Hmm, weird. I have 3 Festool (not Felder :D) vacs, Kapex and a slew of their powered tools. Never once have I tripped a breaker in my shop and all 3 vacs are plugged in 24-7.

[Jim Becker]

Hmm, weird. I have 3 Festool (not Felder :D) vacs, Kapex and a slew of their powered tools. Never once have I tripped a breaker in my shop and all 3 vacs are plugged in 24-7.
Are your breakers AFCI breakers? (Arc Fault) That's what's at discussion here.

[Michael Burnside]

Are your breakers AFCI breakers? (Arc Fault) That's what's at discussion here.

Yes, they are now required in my area and were code when my shop was built 2.5 years ago. I missed the window and had to buy $200 breakers for my 240V tools when a month before $40 ones were sufficient...:(

Edit: And to be honest, I was worried my CNC, SawStop, bandsaw, drill press, 15" Planer, 8" Jointer would have problems but I've not had a single issue in the 2.5 years the shop has been operational. Same goes for all 120V circuits.

[Karl Loeblein]

Mind saying the make and model of the AFCI breaker that’s tripping? I suspect their still working the kinks out on some of these AFCI breakers so keep an eye out for a new model assuming you decide/required to keep an AFCI breaker installed.

[Jim Becker]

Yes, they are now required in my area and were code when my shop was built 2.5 years ago. I missed the window and had to buy $200 breakers for my 240V tools when a month before $40 ones were sufficient...:(

Edit: And to be honest, I was worried my CNC, SawStop, bandsaw, drill press, 15" Planer, 8" Jointer would have problems but I've not had a single issue in the 2.5 years the shop has been operational. Same goes for all 120V circuits.

I'm thankful I wasn't faced with that for the new shop building...we are still using the 2014 NEC here. My panel allowed for snap on neutral for the 120v GFCI breakers and that also saved money.

[Michael Burnside]

I'm thankful I wasn't faced with that for the new shop building...we are still using the 2014 NEC here. My panel allowed for snap on neutral for the 120v GFCI breakers and that also saved money.

Yes, literally less than 2 months before we started they transitioned to 2020 and my electrical bid went up 10% in parts alone. I did tell my electrician not to cheap out on these breakers and we ended up going with Eaton for all the 240V tools and a few other circuits. They were about 30-40 bucks more (~$200 each!) than the HD/Square-D versions we could get locally but so far they perform just fine.

[Rod Sheridan]

Kapax was definitely off when it happened. I can't remember if the vacuum was ever off vs on auto. I doubt it was off as when it is on that side of the workshop it's usually has either the Kapax or a sander plugged in.

No bluetooth.

Electrician said he has seen it a lot with "smart" devices. He suspects that there is a constant current drain to run the smarts and that current is "leaking". He doesn't really know but googling for it seems to confirm that nuisance tripping is common.

Hi, anything with electronics that's always on, such as a smart vac has a small DC power supply in it.

The power supply will have a capacitor in it, which will charge when power is applied. This causes a tiny arc as you insert the cord cap into the receptacle, this can be detected by the AFCI........Regards, Rod.

[Karl Loeblein]

What is the make, model and version of the AFCI that’s tripping? I wonder if other AFCI designs might work better in this circumstance. I’ve read some people are having better luck using AFCI/GFCI combo breakers.

As far as me, I only have GFCI and regular breakers in my shop. Although code enforcement did require AFCI breakers be installed for two additional bedrooms added to my house. Those are made by Cutler Hammer, and the only time those have tripped are when my incoming power lines kicks on & off rapidly during big thunderstorms.

[Wes Grass]

Wierd one here. Plugged in my Fein vac' and the fridge next to it shut off. Tripped the GFI outlet. Pull plug to reset, fridge comes back on. ??????

Plug it back in, fridge goes off. Check the nightlight on an outlet strip on the same circuit. Goes out, comes back on.

Plug vac' into the outlet strip instead, everything stays on.

Start vac', doesn't run, power is still on ....

Duh, position II, not I for auto start...

Had me going for a minute ...

I think these outlets are too old to have arc fault. But is that maybe what they are? Circuit includes all the outlets on the back porch. House is 27 years old.

[Jim Becker]

Wes, if you had Arc Fault breakers, you would have been heading to your panel to reset them if they fired off...

[Wes Grass]

Thanks Jim,

I'm assuming they don't make these as 'outlets'? I'm 'old and out of touch' ;-)

Not many GFI's in the sub panels here. 2 or 3 subs off the main. These are off the 'pantry', feeding the kitchen, garage, porch.

A bit bigger than my 'cabin' in CA, Santa Cruz mountains, which has a main panel out in the rain ... when you have to access it ... great fun ...

Getting drenched in a downpour here in Austin is a blessing ...

[Jim Becker]

I could be wrong, Wes, but I believe that Arc Fault is only at the circuit level via a breaker, while GFCI has been around a long time at both the outlet and breaker level. I tend to use GFCI breakers at this point.

[Michael Rutman]

You said tripped the GFI outlet, so I'm assuming you have a ground fault and the filtered power strip is hiding it. An arc fault is at the breaker box not the outlet (which I think is what Jim is saying).

[Bill Howatt]

There are arc fault receptacles and even combo arc fault and ground fault models. I believe the breakers were the only option some time ago.

[Wes Grass]

Yeah, I was wondering if there was something in the power strip that was isolating it. Didn't think to try a bare outlet on that wall.

'Tripping' the GFI ... it didn't trip and require a reset. Just shut the power off to the circuits and came back on when I pulled the Vac's plug back out.

That's what really has me baffled. Maybe old and in need of replacement? It's done it's job properly in a couple of other cases not too long ago.

[Bill Howatt]

If I understand your post, Wes, that's weird. It seems like the first GFI (likely) from the panel is tripping as far as shutting off the power but it does not latch. AFAIK, if it trips it should stay open circuit and not restore the power until the fault is removed and the GFI's Reset button is pressed. You can usually hear the relay click closed when you do this. Do the test and reset work on the GFIs?