General Stuff

[wattey]

Re: General Stuff

Maybe I am a Cynic but I would bet that the Insurance companies had a hand in making the device part of the code.

Bottom line is the insurance companies foot the bill for fire damage to a house/business. An *optional* device like this would warrant an insurance discount. They cant raise the policies of homes without it ... so they have to offer a discount on homes with it. If its Mandatory though ... they don't have to give any discount. I have to wonder how much cash the insurance companies saved when this device became a mandatory one.

In England we have RCD's (Residual Current Devices) .. Exactly the same thing as a AFCI. In my personal experience I think they are a valuable addition to a home. They are not perfect, but then a seatbelt while inferior to a seatbelt and airbag .. is still better than wishful thinking.

AFCI's may not be everything that was hoped, in this, their first incarnation ... but on the bright side they will only get better

Shaine~

 

[bennie]

Re: General Stuff

If insurance companies established systems to prevent all house fires they would go out of business. Preventing fires is not their primary interest, selling insurance is the only purpose.

The more claims, the higher the premiums.

Just think if there was no crime, then the police would have to create some.

 

[roger]

Re: General Stuff

Bennie,

Preventing fires is not their primary interest, selling insurance is the only purpose.

unfortunately I have to wonder if this may be true in some disease cures.

I mean, I can see all the research being a much bigger business than finding and applying a cure. (I really hope I'm off base in wondering this though )

Roger

 

[iwire]

Re: General Stuff

Happy Sunday everyone.

 

[tonyi]

Re: General Stuff

Alex, I think an important testing aspect frequently left out of the "lab environment" type tests is that of real world type contaminations that may be present where the arc occurs.

ex. take the frayed lamp cord type scenario. What would happen when something like animal piss,tracked in road salt, or ordinary rain water (not things uncommon to find soaked into rugs) is added to the equation. Concentrations of conductive salts or acids has to be a factor in an arc's ability to restart.

I say this because I've got an example of a severely arc damaged 12-3 I cut out of a place about 2 years ago. 4" of copper on all 4 concuctors is completely vaporized/gone, but then there's another 4" or so where the arc started to peter out. From the way the damage in the remaining 4" section is configured, I can see most of the arcing was from line-neutral or line-gnd arcs. The insulation damage is like you striped down one side of the conductor with a knife, so you know it had to be arcing to a similar bare spot on the conductor next to it. About 2" past the total vaporization point, the black and neutral stopped as high energy participants (not vaporized anymore, some insulation present), then the severe (vaporized) damage continued on with only the gnd/red for another inch, gnd being vaporized for about a 1/4" more than the red, then apparently the whole thing petered out.

Key factors here - this was an old cloth sheathed NM with the undersized gnd, *and* it was in a damp environment stapled to a frequently wet basement sill (the place had roof drain problems that would soak one wall all the time)

[ January 04, 2004, 12:46 PM: Message edited by: tonyi ]

 

[alex winkler]

Re: General Stuff

Tonyi,
I completely agree with you about testing, whether it is done in the back of a shop or in a fully equipped UL lab there is no way to test all the different possibilities that can occur in “real life”. Being the skeptic I am, I did the testing just to satisfy myself and to see how AFCIs would work on likely faults here in my shop.

The arcing you saw sounds severe, and if the amperage was above 75-amps an AFCI would have been able to detect the parallel fault, if the GFP did not see the line to ground fault first.

If manufactures could replicate faults like you described, and an AFCI was shown to prevent them, I would have more confidence in their claims. I think some of the tests that are used now for AFCIs verse standard circuit breakers are biased towards AFCIs. They should use available fault currents that are found in the average bedroom circuit when testing. The carbonized arc test is done by passing 12,000 volts from a neon transformer for a few seconds then 120 volts from an AFCI fed circuit through a damaged piece of NMB over and over until the AFCI trips. I checked my bedroom circuits, and none of them had 12,000 volts on them.

That said, when they roll out the new AFCIs with the 5-amp trip setting we will really have something! I may even change out the old piece of junk panel in my house so I can install them on every circuit.