AFCI tripping

[Altz-]

I have wired two new bed rooms and put each room on a AFCI breaker. When I turn on the power everything works fine until I turn on the lights. Then the breaker trips and I cannot figure out why. Can anyone help me with this problem?

[Tomi Engdahl]

According to UL 1699, Standard for Arc Fault Circuit Interrupters, an arcing fault is an unintentional arcing condition in a circuit. Arcing is defined as a luminous discharge of electricity across an insulating medium, usually accompanied by the partial volatilization of electrodes.

As defined in UL 1699, Standard for Arc Fault Circuit Interrupters, an Arc-Fault Circuit Interrupter (AFCI) is a device intended to mitigate the effects of arcing faults by functioning to de-energize the circuit when an arc fault is detected.

Siemens AFCIs consist of a thermal magnetic circuit breaker with an electronic circuit board. The electronics detect the arc and activate a solenoid to trip the breaker.


All AFCI’s have a built in Ground Fault Interrupter, set at 30 mA to 50 mA. This is not a “Class A” GFCI, but functions in the same way. Many of the installations where an AFCI trips is not due to the Arc Fault portion tripping, but rather an inadvertent neutral to ground connection.
Tripping GFCI’ and now AFCI’s have shown there are miswired and inadvertent neutral to ground connections.
To confirm a suspected ground fault in the permanent wiring, remove all
power from the circuit by opening the AFCI. Also, disconnect all appliances
from the circuit. Then, look for low resistance between line and ground or
between neutral and ground, indicating a ground fault.


As with most circuit breakers, an AFCI has an electromagnetic function that opens almost instantaneously when it detects a short circuit, typically in less than one-tenth of a second.
A special type of ground fault (but a frequent one) is an inadvertent
grounded neutral. This occurs when the neutral conductor contacts a
grounded conductor (ground wire, grounded outlet box, etc.). This can
happen in a receptacle box, switch box, or a fixture. When this condition
occurs, the balance between the line and neutral currents no longer exists
and the AFCI trips.



One phenomenon that appears as a short circuit to a circuit breaker
(including AFCIs) is high inrush current. High inrush current can occur when
several loads (or one large load) are connected to the switched half of the
receptacles. If all the individual loads are turned ON, flipping a light switch
ON can subject the circuit breaker to a momentary high inrush that far
exceeds the normal operating current of these loads. This will appear as a
short circuit to an circuit breakers and cause it to trip. The solution to this
situation is to simply plug most of the load into the non-switched side for
lighting. (This will prevent turning on several of the loads simultaneously.)


There can be two causes for an AFCI to trip when all other possible causes
have been dismissed: either the AFCI is damaged or was installed
improperly.

Some equipment can trip some AFCI devices for some reason when nothing is wrong.
But using the vacuum opened the breaker so fast, the motor didn't even have a chance to get started. It was virtually instantaneous. Yet when they plugged the vacuum into another outlet that was protected by a standard thermal breaker, it worked fine.

Blaschka said that in his house, the outlets in the bedrooms as well as those in the hallways in the bedroom area are AFCI-protected. So, powering the vacuum from an outlet that doesn't have an AFCI is generally inconvenient.

There is plenty of documentation on the Web describing botched installations and pre2005 AFCIs that were recalled. But Blaschka isn't Joe Homemaker. He's a licensed Professional Engineer. He said he had detailed conversations with the AFCI manufacturer, who simply blamed the vacuum maker.

In the end, Blaschka bought a new vacuum for the bedrooms, and it only creates false AFCI trips 10% of the time. But that's not a very satisfactory end. Evidently, AFCIs provide safety, but they also have a threshold problem. Could universal appliance motors be fitted with low-pass filters? Would they work? Is there an aftermarket for external LP filters?

One poster on a consumer-forum thread described how one AFCI in his new house seems to be tripping at random. "I could not find a pattern,"..


Information sources:
http://www2.sea.siemens.com/Products/Re ... rcingfault?
http://www.mikeholt.com/mojonewsarchive ... 030320.htm
http://www.cpsc.gov/CPSCPUB/PUBS/afcifac8.pdf
http://ecatalog.squared.com/pubs/Circui ... rs%20(AFCI)/QO/0760DB0204.pdf

More information:
Determining the Cause of AFCI Tripping
http://ecatalog.squared.com/pubs/Circui ... rs%20(AFCI)/QO/0760DB0204.pdf
http://www.elecdesign.com/Articles/Inde ... 4&bypass=1


Video link:
http://www.youtube.com/watch?v=liXlvWfLUZ4

[T Taylor]

I had a problem with my AFCI tripping and found that my "X10 Audio/Video Sender" was and is causing the problem. I have the device sending the AV from my VCR/DVD player recorder to a TV in a room without a cable connection. The device works fine but the RF from the device trips the AFCI for the guest bedroom and computer room circuits. When the "X10" device is not in use there is no problem. I had a similar incident where my GFCI would trip when using the "FM Wireless Intercom" from the house to my shop in our home.

So Remote fan/light controls could be a problem as well as the remote emits an RF signal but a very low power signal I think a less of a problem unlike the X10 device I am using.

My experience is Electrician and electronics of all sorts, two way radio, cellular, two way satellite communication, data circuits, telephony. Basically if you communicate with it I worked on it (Now Retired) except the mouth--I'm not a Dentist!