AFCI to rescue?? maybe not??

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mbrooke said:
It won't sadly, the leakage is resistive. IMO I think this is a perfect example of why work quality will out do any safety device ever mandated.
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Right, it's current flow into the wood. No actual arcing is taking place. AFCI one again proves how worthless it is.
 
peter d said:
Right, it's current flow into the wood. No actual arcing is taking place. AFCI one again proves how worthless it is.
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But not worthless to the AFCI myth. It was this very hazard that was spun around into arcing giving birth to the over driven nail theory. The over driven staple weakens the insulation enough to not dielectric break down, but enough so the lightning strikes and surges "punture" the weak spot. That weak spot then arcs on 120 volts and in a short amount of time the stud ignites- hence a perfect (on paper) explanation why over driven staples take years to show up. But the reality that UL and every other AFCI pusher chooses to ignore is that the staple or nail is live with 120 volts since day one. Arcing and short circuits are the end stage when the wood finally starts to smolder and burn from pyroforic canonization- not the start. Greatest spin ever told...
 
mbrooke said:
Its microamps from what I've heard. Enough to heat the wood over the course of years if not decades ever so gradually.
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I was going to ask how many years it may take for this to happen, and figured it would have to be in the decades ranges. Then you mentioned the lightning strike situation and how it may accelerate things. Seems lightning could accelerate this even if there isn't an over driven staple involved.

I think the risk of starting a fire with a lighting fixture mounted on a wood surface or a recessed can in contact with wood would be a higher risk. The heat dries out the wood over time and lowers ignition point, you have more heat here then you wood:) with the microamps flowing in the conductor to wood fault situatiuon.

mbrooke said:
But not worthless to the AFCI myth. It was this very hazard that was spun around into arcing giving birth to the over driven nail theory. The over driven staple weakens the insulation enough to not dielectric break down, but enough so the lightning strikes and surges "punture" the weak spot. That weak spot then arcs on 120 volts and in a short amount of time the stud ignites- hence a perfect (on paper) explanation why over driven staples take years to show up. But the reality that UL and every other AFCI pusher chooses to ignore is that the staple or nail is live with 120 volts since day one. Arcing and short circuits are the end stage when the wood finally starts to smolder and burn from pyroforic canonization- not the start. Greatest spin ever told...
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Add: to have the open neutral situation cause a fire as posted in that pic with the grounded box injecting neutral current into the wood, not that that situation isn't totally impossible but for worst effect the neutral has to be totally open, and you would think that would cause enough other troubles that it would get repaired long before it causes a fire at that particular box location, let alone the fact that there are many more EGC contact points to the wood structure then just at that one box shown in the picture so it is only one part of a network of parallel paths through the wood.
 
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kwired said:
I was going to ask how many years it may take for this to happen, and figured it would have to be in the decades ranges.
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My understanding is that its at least a few years to decades.


Then you mentioned the lightning strike situation and how it may accelerate things. Seems lightning could accelerate this even if there isn't an over driven staple involved.
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How so though? Not say your wrong though.

The lightning theory in its official explanation is two fold:

1. It is used to explain marginal (weak point) insulation blowing off the copper conductor, which in turn leads to:

2. A carbonized path forming from the momentary multi kv arc. 120 volts can not self sustain an arc by itself, however a heavily carbonized path created by very high voltage (prior) can pass current at 120 volts, a.k.a "sustained arc fault"

Once this arc takes place, its said the heat is so intense that the wood member ignites leading to a fire.



I think the risk of starting a fire with a lighting fixture mounted on a wood surface or a recessed can in contact with wood would be a higher risk. The heat dries out the wood over time and lowers ignition point, you have more heat here then you wood:) with the microamps flowing in the conductor to wood fault situatiuon.
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It can happen, but Id argue low level current leakage can dry out the wood far more thoroughly as there is never a break from the constant, minute, low level heating. I know the concept is hard to grasp, but keep in mind the Grand Canyon is said to have been created entirely by erosion (mostly water) over millions of years.
 
kwired said:
I think the risk of starting a fire with a lighting fixture mounted on a wood surface or a recessed can in contact with wood would be a higher risk.
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:huh:

An IC can is suitable for insulation contact, often the paper face on the insulation is in contact with the light especially in new construction. I've never heard of the paper catching fire, let alone the wood.
 
peter d said:
:huh:

An IC can is suitable for insulation contact, often the paper face on the insulation is in contact with the light especially in new construction. I've never heard of the paper catching fire, let alone the wood.
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I should have said a non IC can.

Been years since I used to buy both IC and non IC cans , only difference between the two that I was buying was they had different thermal protectors so I would assume trip point of the protector was at a different temperature. The non IC cans were generally rated for higher wattage lamps in same trim then if using a IC rated can, but if installed properly should be able to dissipate the extra heat safely.

I have seen charred wood behind surface mount fixtures before - especially if it were subject to too high of wattage lamps being installed.
 
kwired said:
I should have said a non IC can.

Been years since I used to buy both IC and non IC cans , only difference between the two that I was buying was they had different thermal protectors so I would assume trip point of the protector was at a different temperature. The non IC cans were generally rated for higher wattage lamps in same trim then if using a IC rated can, but if installed properly should be able to dissipate the extra heat safely.

I have seen charred wood behind surface mount fixtures before - especially if it were subject to too high of wattage lamps being installed.
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Yes, those old drum fixtures where people would install 3 -100 watt lamps were notorious for that.
 
mbrooke said:
But not worthless to the AFCI myth. It was this very hazard that was spun around into arcing giving birth to the over driven nail theory. The over driven staple weakens the insulation enough to not dielectric break down, but enough so the lightning strikes and surges "punture" the weak spot. That weak spot then arcs on 120 volts and in a short amount of time the stud ignites- hence a perfect (on paper) explanation why over driven staples take years to show up. But the reality that UL and every other AFCI pusher chooses to ignore is that the staple or nail is live with 120 volts since day one. Arcing and short circuits are the end stage when the wood finally starts to smolder and burn from pyroforic canonization- not the start. Greatest spin ever told...
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So in summary, an AFCI cannot detect:

1) A glowing connection

2) Pyrophoric carbonization taking place

3) A ground fault under 30 milliamps of current flow

4) Any fault current flow at all in some models where there is no GFPE whatsoever




So what is it they do exactly? :?:roll:
 
peter d said:
So in summary, an AFCI cannot detect:

1) A glowing connection

2) Pyrophoric carbonization taking place

3) A ground fault under 30 milliamps of current flow

4) Any fault current flow at all in some models where there is no GFPE whatsoever




So what is it they do exactly? :?:roll:
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There is a theory that if you keep your money in a hole in the ground, it does no one any good. :)
 
peter d said:
So in summary, an AFCI cannot detect:

1) A glowing connection

2) Pyrophoric carbonization taking place

3) A ground fault under 30 milliamps of current flow

4) Any fault current flow at all in some models where there is no GFPE whatsoever




So what is it they do exactly? :?:roll:
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Both better replies but sort of on same path that what I was going to mention:

big john said:
Give many millions to breaker manufacturers at the expense of ECs and their customers, while significantly eroding confidence in the objectivity of the CMPs! Yay!
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ptonsparky said:
There is a theory that if you keep your money in a hole in the ground, it does no one any good. :)
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big john said:
Give many millions to breaker manufacturers at the expense of ECs and their customers, while significantly eroding confidence in the objectivity of the CMPs! Yay!
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:thumbsup:

Don't forget the decade plus of free R&D the manufacturers got on the customer's dime.
 
peter d said:
So in summary, an AFCI cannot detect:

1) A glowing connection

2) Pyrophoric carbonization taking place

3) A ground fault under 30 milliamps of current flow

4) Any fault current flow at all in some models where there is no GFPE whatsoever
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Yup, spot on :thumbsup:

So what is it they do exactly? :?:roll:
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Make $$$$ for the manufactures and UL. That and trip on listed appliances :lol::happyno:
 
peter d said:
So in summary, an AFCI cannot detect:

1) A glowing connection

2) Pyrophoric carbonization taking place

3) A ground fault under 30 milliamps of current flow

4) Any fault current flow at all in some models where there is no GFPE whatsoever




So what is it they do exactly? :?:roll:
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Cost more money, and make perfectly good appliances work intermittently. AFCI also cannot be tested by any meter I'm aware of; if they pass a self/push button test, they are "good", if not, they aren't.

At this point we can only hope they work better, or get removed in entirety by the 2020/2023 codes. I bet there are many electricians that would gladly remove them for free just to get the enjoyment of hearing them "THUD" in the bottom of a dumpster. and MH forum topic/post count drops 5% overnight lol.
 
JFletcher said:
...At this point we can only hope they work better....
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Honestly, at this point it seems completely inexcusable to me that they don't.

It's been almost two decades. In that time computing power has gone from a 20 pound beast that sat on a desktop, to a far more functional device that fits in your pocket. But for some reason the processing power and algorithms in AFCIs still routinely screw up after 18 years of field trials?

I'm sorry the technology us junk, but it apparently is. At what point do we admit thar 30mA GFP would be a far safer and less nuisance prone technology?

But then again this is the same dinosaur code that still insists on calling a bond wire an equipment ground, so my hopes are pretty slim that they'll realise the error of their ways.
 
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