Previous in Forum: Separate earthing   Next in Forum: Odd LED operation
Close
Close
Close
7 comments
Commentator

Join Date: Apr 2011
Posts: 99
Good Answers: 5

Do AFCI breakers sense the incoming power

01/04/2022 9:50 PM

A neighbor just built a new house and installed a 200A panel loaded up with Square D DF/AFCI breakers. A few weeks later some sort of surge came through and wiped out the incoming surge suppressor and all the breakers, several of their LED light fixtures and a furnace control board. They replaced everything and all worked well for a couple of weeks then all the AFCI breakers tripped. Is there a possibility these breakers are seeing some sort of fault situation on the incoming power?

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 31000
Good Answers: 1725
#1

Re: Do AFCI breakers sense the incoming power

01/04/2022 10:33 PM

"The AFCI (Arc Fault Circuit Interrupter) protects against fires caused by arcing faults. ... The GFCI (Ground Fault Circuit Interrupter) is designed to protect people from severe or fatal electric shocks. A ground fault is an unintentional electric path diverting current to ground."...

https://www.ssf.net/home/showpublisheddocument/2410/636396919815400000#:~:text=The%20AFCI%20(Arc%20Fault%20Circuit,fires%20caused%20by%20arcing%20faults.&text=The%20GFCI%20(Ground%20Fault%20Circuit,path%20diverting%20current%20to%20ground.

It sounds to me like there was a lightning strike near the home and some damage has been done....if the problem persists I would hire a good electrical troubleshooter to find and correct the problem....Surge suppressors are designed to fail under extreme surge conditions, so this would indicate to me a lightning strike got into the wire, and the path of a nearby lightning bolt cannot be predicted, it can travel in an unpredictable path....so the first step is to replace everything that has apparent damage, and wait to see if any unseen problems might surface in the near future..then a more comprehensive examination of the system can begin....The ground and arc faults deal with wiring on the home side of the breaker box, the surge suppressor is for incoming....

"The two main causes for nuisance tripping at AFCI circuit breakers are improperly wired circuits and incompatibility with electronic devices. ... Another wiring problem is more of an incompatibility issue than a wiring issue, and it has to do with multi-wire circuits.Feb 23, 2016

Unfortunately afci breakers are well known for nuisance tripping...

https://structuretech.com/nuisance-tripping-afci-breakers/

https://petersonelectricllc.com/tripped-afci-breakers-reasons/

__________________
Break a sweat everyday doing something you enjoy
Register to Reply
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 30321
Good Answers: 817
#2

Re: Do AFCI breakers sense the incoming power

01/05/2022 3:02 AM

Downstream, yes. Upstream, no.

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply
Guru

Join Date: May 2006
Location: Placerville, CA (38° 45N, 120° 47'W)
Posts: 5989
Good Answers: 242
#3
In reply to #2

Re: Do AFCI breakers sense the incoming power

01/06/2022 1:23 AM

"Downstream, yes. Upstream, no."

I'm confused! Since energy is flowing from a source, through the breaker panel and into the house (or other structure), I would assume that "Downstream" would mean inside the house, and "Upstream" would mean outside the breaker panel, toward the source.

Thus the "Incoming power" would be from "upstream", so if the breaker can sense the incoming power, It would have to sense from upstream.

Please clarify!

__________________
Teaching is a great experience, but there is no better teacher than experience.
Register to Reply
Guru

Join Date: Jul 2006
Location: Eastern Kansas USA
Posts: 1409
Good Answers: 121
#4

Re: Do AFCI breakers sense the incoming power

01/06/2022 12:33 PM

Friends,

A reasonably decent description of AFCI function is in this source. A GFCI is looking at the current imbalance between the two conductors in a circuit, so it is only responding to what is on its load or downstream side. Since an AFCI is looking only at the wave form of the energized conductor I strongly suspect it can be influenced by incoming signals.

Either one, as well as almost all electronic systems in a home can be damaged by voltage spikes or surges. A simple surge arrestor has a series of MOV's (metal oxide varistors) which have a high resistance at voltages less than 1.5 to 2 times the peak voltage in a circuit, but have a very low resistance when the voltage is higher. They look like flat disks with a wire attached to each side at an angle. They can and will fail if the voltage spike is too large or too energetic, and often explode when that happens. To prevent additional damage the device they are in should include a fuse to shut off excessive current flow. Because the voltage surge/spike is very brief the conductors between an incoming line surge arrestor and the incoming line must be as straight and short as possible, and it must be fed from a suitably sized circuit breaker (or fuse).

I said peak voltage--that is ~1.4 times the nominal circuit voltage. Thus a typical 120-volt circuit has a peak near 170 volts, but since the nominal circuit voltage can occasionally be 10% higher, lets assume the peak is not over 185-190 volts. Thus for safety to the surge arrestor the MOV has to allow any surge lower than about 300 volts to pass through. Many more complex surge arrestors include additional components to limit the surge voltage even further (at a price).

About 35 years ago I regularly serviced a commercial swimming pool and had to replace over half of the GFCI breakers each spring, because of lightning storm damage during the off-season. I installed a surge arrestor and had no further GFCI damage for many years afterward. Yeah, they work.

--JMM

Register to Reply
Guru

Join Date: May 2018
Location: Under the spreading Bunya Trees, South Burnett, Queensland, Australia
Posts: 613
Good Answers: 57
#5

Re: Do AFCI breakers sense the incoming power

01/06/2022 11:52 PM

No the breakers only sense an imbalance after the breaker between the active/hot and Neutral which means the imbalance is flowing to earth before returning to the source.

Now a bad earth connection can cause spurious tripping. You do not say if the panel is single or multiphase which can also cause imbalances. VFDs, capacitive Circuits as in computers, SMPS, lights can all cause inrush currents which the breaker can see as an earth fault.

Protecting the board itself with a core balance CT, controlling a shunt trip breaker, which measures the total imbalance and is set to trip at a leakage current above the individual circuit breakers provides trip discrimination.

With the tripping after the replacement could mean that some neutral or earth problem exists from the initial surge damage.

__________________
Hare today, goon tomorrow!
Register to Reply
Participant
Australia - Member - New Member

Join Date: Jan 2022
Posts: 2
#6

Re: Do AFCI breakers sense the incoming power

01/07/2022 5:34 PM

When you say "..surge came through and wiped out the incoming surge suppressor and all the breakers ", does that mean the breakers were destroyed and had to be replaced, or just that the breakers had operated (tripped)?

If the former, then this is a very rare event, and the surge must have been quite severe, in which case I would not be surprised to find that other parts of the installation that were not replaced had sustained some damage from that event, and may now be causing the tripping that is occurring - for example, the cabling within the house, or the bus-bars of the distribution board. How often have the AFCI breakers tripped after they were replaced?

If the latter, then all I can say is that tripping of breakers during a surge event is quite normal - particularly breakers that have current imbalance trip (earth leakage), which is a feature of both the DF and AFCI breakers.

If the AFCI breakers continue to trip often, then an investigation is required, perhaps there is some damage to the cabling within the installation, this damage may cause leakage to ground, thus tripping earth leakage breakers. Some breakers will indicate what type of fault caused the trip, eg: short-circuit, or overload, or earth leakage, and this would be very important information to assist with any investigation.

The other clue here is when you said " all the AFCI breakers tripped ". Did they all trip simultaneously? If so, then that would suggest the fault lies on the supply side of the breakers, since it would be very rare to have faults occur simultaneously on all of the load circuits. Another possibility is that another surge occurred that perhaps did not cause any other observable effects apart from tripping all the breakers simultaneously. The other possibility is that some kind of electromagnetic pulse had occurred that was sufficient to trip earth leakage breakers.

All the best with the investigation. Cheers.

Register to Reply
2
Commentator

Join Date: Apr 2011
Posts: 99
Good Answers: 5
#7
In reply to #6

Re: Do AFCI breakers sense the incoming power

01/08/2022 8:59 PM

Well, the rest of the story.

The utility company finally admitted there was a transformer failure that caused the initial surge that damaged the first installation of breakers, the surge suppressor and some of the house equipment.

The second set of breakers installed, worked until the owner was setting the cover on the panel. All the odd breakers were tripping and would not reset. It was discovered that a bonding bolt on a neutral buss bar was missing. Dropping the neutral from all the odd breakers and “smoked” ‘em

Register to Reply Good Answer (Score 2)
Register to Reply 7 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".
Copy to Clipboard

Users who posted comments:

Cascoder (1); deanpavil (1); dkwarner (1); jmueller (1); PWSlack (1); SolarEagle (1); Stef (1)

Previous in Forum: Separate earthing   Next in Forum: Odd LED operation

Advertisement