EEs - X10 tripping ArcFault Breaker

[NW-Bound]

Wow! I thought that an inductive load (ie coils, motors etc.) was necessary to get the significant arcing shown in the video.

The heating coil load appears to be mostly resisitive (ie very small inductance).

I guess that I might need to retest for that 'EE' degree granted 30 years ago - or remember that I am not an electrician!

-gauss

Don't feel bad. They do not teach this in college unless you take a class in power engineering. Many people do not know about the peculiar danger that high voltage DC power carries. For example, I am sure most EEs do not appreciate the fact that regular AC circuit breakers cannot handle high-voltage DC circuits.

The DC arcing is caused by the air being ionized, followed by metal being vaporized from the end of the arc. As the above video demonstrates, an arc of more than 1-inch long is easily sustained by the current in a 20A circuit. The circuit must be able to supply a high enough current to feed the arc.

DC breakers use internal magnets to deflect/suppress the arc, and must be installed with the proper current flow direction in order to work. Else, the internal arcing prevents the current from getting interrupted. In fact, the internal arcing sets the breaker on fire. To appreciate this, watch the video below.

 

[NW-Bound]

OK. So, if one uses the right breakers and installs them correctly, is it all honky dory now?

As I said earlier, what about an unintentional break in the circuit elsewhere? A loose connection, a corroded terminal, etc...?

Look at the photos below. And what about a circuit break inside a solar panel itself, as the video at the bottom demonstrates?

 

[RobbieB]

I'm glad I went with micro inverters.

 

[Winemaker]

Did you install the arc breaker in a different circuit to see if it acts the same?

 

[travelover]

Did you install the arc breaker in a different circuit to see if it acts the same?

No I have not. Still hoping for a lazy answer.

 

[Telly]

.......48V is not high enough to cause a serious problem. I am still trying to look up some numbers, but a few sources indicate that 80VDC is about the limit where serious consideration must be taken to safeguard against arc faults and associated fire hazard.......

For me as a product designer, my issue was degradation/welding closed of the contacts due to the arc. That would have been a product reliability disaster. IIRC (it's been a looong time, and designed so many things since then), the contacts were silver.

The 1980s Hinsdale fire reset many peoples thoughts about the flammability of electronic equipment, and the capability of a DC arc in nominal 48 v (usually about 52.6v) feeder wiring to do tremendous damage to our communication infrastructure.
Among many rules and regulations, it hastened the proliferation of Halon systems, and the stern warning to everyone in the environment "if the Halon alarm goes off, get the hell out, head outside, don't stop for anything!" The nozzles were really big, as flooding the volume with a non-combustion-supporting gas that also reacted with combustion ASAP could be expected to stop a fire pretty quick. Due to the volumes used then, it could also stop people. In time, the use of Halon became more of a science than brute force. I don't think it will help with a solar panel, though

 

[Telly]

I changed out the breaker box with the help of an electrician. All we did was pull out wires from the old breaker box then reconnect them to the new box. The problem seems to be erratic - so maybe it is as simple as a bad connection.

Devils Advocate --A bad connection? Well, maybe the Arc-Fault Interrupter is doing it's job! Put a penny in it

 

[NW-Bound]

I'm glad I went with micro inverters.

Good choice. Divide and conquer.

Companies making string inverters now have devices mounted at each panel to isolate them in a shutdown. But they need a way to reliably detect an arc fault to initiate the automatic shutdown.

Even large commercial solar installations have caught fire before, and at the panels themselves. Scary stuff!

 

[SteveNU]

We redid our kitchen last year and had to put in new AFCI/GFCI outlets in four circuits. Two of the circuits are new runs and two were existing. Since then they have all had numerous random spurious trips. Sometimes just sitting there with nothing plugged in. I'm ready to go back and change them all to just GFCI and see how that works.

 

[NW-Bound]

We redid our kitchen last year and had to put in new AFCI/GFCI outlets in four circuits. Two of the circuits are new runs and two were existing. Since then they have all had numerous random spurious trips. Sometimes just sitting there with nothing plugged in. I'm ready to go back and change them all to just GFCI and see how that works.

I have a nagging suspicion that the GFCI's will work fine.

 

[NW-Bound]

While another person has reported sensitive AFCIs with nuisance tripping, I shared in post#9 how an electrician could not get his to trip with an induced real arc fault.

Here's another one who could not get his AFCI to trip.

 

[travelover]

While another person has reported sensitive AFCIs with nuisance tripping, I shared in post#9 how an electrician could not get his to trip with an induced real arc fault.

Here's another one who could not get his AFCI to trip.

I guess that is the brand I should have bought. Meets code, no tripping.