AFCI breakers tripping

jlimey

Jeff
Senior User
Hi,

I am renovating an old home and had the entire structure rewired from knob and tube. Being a woodworker who can barely plug in his tools, I left the wiring to an electrical firm. :)

Anyway, while working on the porch trim, I could not use my Dewalt miter saw without tripping the circuit. The painters were also not able to use their compressor for spraying on these circuits. I am able to run my 10.5 amp belt sander without them tripping.

The electrician came out and checked the circuit (it has a 20 A AFCI breaker, BTW). He blamed the lack of sophistication of the breaker for it being so sensitive. If true, are there better breakers?

So the question to the esteemed readers with wiring knowledge, is this a reasonable answer? Does it indicate that there is a problem that needs to be resolved before I pay for the work? The bill is due but I don't want to pay if something needs to be done.

Thanks for the advice!

Jeff
 

Skymaster

Jack
Senior User
remove the afci breaker and replace with standard breaker, when work is finished, then put afci back
 

Gofor

Mark
Corporate Member
Sounds to me that it should be a GFCI, (ground fault current interrupter) if it is the porch circuit, not an AFCI (Arc Fault current interrupter), or that you are trying to plug into the wrong circuit (i.e a bedroom circuit). That said, if someone has crossed a neutral or ground, a grounded neutral will cause the AFCI to trip as soon as a load is applied. A Outlet/Receptacle tester is cheap, and will tell you quickly if any are wired wrong (i.e. neutral and ground crossed). However, beings you are able to run the sander, that does not sound to be the case.

AFCI's are also more prone to nuisance tripping from inductive loads (i.e motors, like the miter saw or compressor). If it is a 15A circuit, the miter saw and compressor are probably too much for it.

If it were me, I would require that issue to be resolved before final payment of the bill.

For outside or wet areas, GFCI is required to keep you from being electrocuted.

AFCI are designed to detect short circuits like those from frayed wiring inside an outlet box, etc. They are designed to keep your house from burning down due to a short that would ignite a fire. They are required in bedrooms.

Short version: GFCI protects you. AFCI protects your house.

I had heard that the powers that be were thinking about cahnging the code to require AFCIs (definitely more expensive) on more than bedroom circuits, but don't know if that has occurred.
 

marinosr

Richard
Senior User
Universal motors, the kind of motor in portable power tools, will trip AFCI breakers. Look into the air vent of your miter saw motor... you'll see sparks coming off of the carbon brushes. This is normal for any universal motor, but those sparks are indeed exactly the same as the arcs that an AFCI breaker is supposed to protect against. AFCI breakers will often trip erroneously, and I think some of them are engineered in a more sophisticated manner to ignore arcs that occur at a regular interval (such as when the brush of a motor is moving over the commutator of a motor at a regular speed).

Like Mark stated above, I don't know why an AFCI is on an outdoor circuit.
 

jlimey

Jeff
Senior User
Sorry for the confusion. I was plugging into the indoor hallway circuit, which includes a bedroom. Hence the afci.

So far, seems not unusual. Question is should i ask for a separate circuit in the hallway? Since i wont be living there....
 

tri4sale

Daniel
Corporate Member
Sorry for the confusion. I was plugging into the indoor hallway circuit, which includes a bedroom. Hence the afci.

So far, seems not unusual. Question is should i ask for a separate circuit in the hallway? Since i wont be living there....
I wouldn't, people plug similar things in the hallway that they do in the bedrooms that could cause a spark. I would have a non-afci installed outside for times something needed to be done outside.

I had same issue with treadmills in my addition I added with the afci breakers. Few days ago talked with an electrician and that came up, he did say you can get better afci breakers that aren't as sensitive to things like that, but they do cost alot. afci has turned into one of those "safety improvements" that are a inconvenience in real life, so I've seen multiple cases where people just swap them out for non-protected breakers which defeats the purpose.
 

kserdar

Ken
User
I had the same problem with my brand new home. AFCI breakers were tripping in Master and guest bedroom with nothing plugged in.
The electrician waited until after county inspections were signed off. Then returned to replace them with normal breakers.
 

junquecol

Bruce
User
Any safety device that doesn't work for designed purpose isn't a safety device. Once, replacing a ceiling fan, with power shut off at wall switch, every time I took a wire loose, or connected one together, the AFCI would trip.
 

Gofor

Mark
Corporate Member
Changing the hall circuit could be a major issue, especially if the sheet rock is up. However, if the circuit won't run what you may need in the future, for instance the household vacuum cleaner, you may want to upgrade that specific breaker. We have no problems with vacuum cleaners or carpet scrubbers plugged into our AFCI bedroom circuits.

I would suggest just plugging into a different circuit for construction work.
 

Phil S

Board of Directors, President
Phil Soper
Staff member
Corporate Member
Most manufacturers have an economy line "builder grade" and a quality line. I would tell your electrician to upgrade the breaker to the best
 

Brantnative

Jeff
Corporate Member
NEC 2017 210.12(A) reads: "All 120 volt single phase 15 and 20 amp branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry rooms, or similar rooms or areas shall be protected by any of the means described in (1) through (6)."
(1) through (6) are basically a combination of breaker type and and or receptacle type AFCI.
You either have an actual arc fault being detected or more likely, as Phil suggested there are cheap AFCI's that trip more often, and there are more expensive ones. Considering what they protect I know which one I'd choose.

Always check with an NC licensed electrician.
 

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