Beating the AFCI horse again.

[ptonsparky]

Remodel on a home with new wiring. Pretty much the whole house. Installed AFCIs. Owner calls with age old problem of vacum tripping the AFCI. I explain probably not much we can do and easiest is to plug into kitchen or bath circuit. Yup, he says he just plugged into a different bedroom and things worked fine. Knowing the guys AFCI'd to the 2011, that changes things. My help was on the way to add one last AFCI so the checked it out. Changing AFCIs on that circuit did no good. Only that circuit tripped.
He did not have a megger with him but did have good meter and checked each recept for accidental grounds by removing them from the box and checking again.

Small experiment of adding a 25' length of 14/2g romex at the breaker end of the circuit stopped the tripping. When he left he had extended the hot wire only by looping about 6' of thhn in the panel. Couple times around I would guess. No more trips

 

[readydave8]

When he left he had extended the hot wire only by looping about 6' of thhn in the panel. Couple times around I would guess. No more trips

Has this worked before or is it the first time you tried it?

Why does the extra length on hot prevent nusiance tripping?

 

[ptonsparky]

One of the suggestions for AFCI problems is to change the length of the circuit. First time we've tried it and I had to talk my help thru the process via phone. He was pretty skeptical when I told him to insert the 25 foot piece of romex for a test. I left it up to him as to how much to loop in the panel. Whatever works.

 

[WIMaster]

Thank you for the tip I will have to try that on my next AFCI nuisance call! Man I am learning to hate those things.:rant:

 

[iMuse97]

Thank you for the tip I will have to try that on my next AFCI nuisance call! Man I am learning to hate those things.:rant:

I hated them in '05 or '02 or whenever they first came out. We had to install them in Illinois, but Indiana adopted the '05 Code sans AFCIs.

NEVER would have thought that an extra length of wire would solve a nusiance trip. Anybody have any idea why or are we starting a new urban legend?

 

[SOG38]

AFCI Hrose

AFCI Hrose

This device senses the arcs and shuts down the power to prevent a fire. This is a good thing. I think the issue that I have seen several posts about always involves universal motors. Vacuums, drill motors, Circular saws. They all have brushes they all have small arcs. As the brushes and motors age the sparks increase. The AFCI trips.
It sounds like it is doing its job. I would be concerned about adding extra lengths of wire as it may mask a real arc till it will cause a fire and the AFCI doesn't trip.
The extra wire is adding inductance to the circuit I think that is why it is masking the motor arcing.
A small ac capacitor across the motor would be a much better fix in my opinion.

 

[ELA]

NEVER would have thought that an extra length of wire would solve a nuisance trip. Anybody have any idea why or are we starting a new urban legend?

I had studied AFCI operation a little over a year ago and posted details here. It is the added "impedance" that prevents the tripping.
These devices look at the high frequency content in the current being drawn. The high frequency content has to match both a certain amplitude and range in frequencies.

When you add impedance to the circuit you reduce the amplitude of the high frequency. My suggestion would always be an EMI filter located at the load!

Consider that actual and potentially dangerous arcs are also being detected using the high frequency content. If you prevent a nuisance trip are you also preventing the detection from working properly when it is most needed?

This is exactly why there should be a mandatory test done on all AFCI installations (in my opinion) to check the circuit impedance to assure that it is not too high to allow the AFCI to work properly. (If they are to be required that is). From direct testing I can tell you that the "Test Button" is not assuring proper (in-circuit) operation - an external tester could.

 

[ptonsparky]

Adding 6 feet of wire is no different then perhaps adding a switch to a receptacle directly below it.

I agree perhaps a surge device might be better, but are you sure it is not going to suppress what the AFCI is looking for any less then ___ feet of wire. My thoughts would be to greater suppression.

Adding a capacitor to any appliance is just unrealistic.

What we did was by no means scientific. It may or may not work ever work anywhere else.

 

[SOG38]

Afci Horse

Afci Horse

Some interesting reading
http://www.iaei.org/magazine/2008/01/understanding-the-combination-afci-expansion-in-nec-2008/

 

[rbalex]

Some interesting reading
http://www.iaei.org/magazine/2008/01/understanding-the-combination-afci-expansion-in-nec-2008/

I looked at the organizations that endorse AFCIs in the last section of the paper:

• Independent Electrical Contractors (IEC),
• National Electrical Contractors Association (NECA)
• International Brotherhood of Electrical Workers (IBEW),
• Underwriters Laboratories(UL)
• Electrical inspection community(IAEI)
• National Association of State Fire Marshals (NASFM)
• Consumer Product Safety Commission (CPSC)

Every one of them have a positive or absolutely neutral financial interest in the installation of AFCIs. The lack of AFCIs costs them nothing. Now if the home insurance industry required, endorsed or gave a rate break for them, I might begin to think AFCIs had real value.

 

[djohns6]

I looked at the organizations that endorse AFCIs in the last section of the paper:

• Independent Electrical Contractors (IEC),
• National Electrical Contractors Association (NECA)
• International Brotherhood of Electrical Workers (IBEW),
• Underwriters Laboratories(UL)
• Electrical inspection community(IAEI)
• National Association of State Fire Marshals (NASFM)
• Consumer Product Safety Commission (CPSC)

Every one of them have a positive or absolutely neutral financial interest in the installation of AFCIs. The lack of AFCIs costs them nothing. Now if the home insurance industry required, endorsed or gave a rate break for them, I might begin to think AFCIs had real value.

I think every one of those organizations stands to gain financialy from the use of AFCI devices .
Either through the installation , trouble calls , sales , or testing and certification process .

 

[Little Bill]

This device senses the arcs and shuts down the power to prevent a fire. This is a good thing. I think the issue that I have seen several posts about always involves universal motors. Vacuums, drill motors, Circular saws. They all have brushes they all have small arcs. As the brushes and motors age the sparks increase. The AFCI trips.
It sounds like it is doing its job. I would be concerned about adding extra lengths of wire as it may mask a real arc till it will cause a fire and the AFCI doesn't trip.
The extra wire is adding inductance to the circuit I think that is why it is masking the motor arcing.
A small ac capacitor across the motor would be a much better fix in my opinion.

I had studied AFCI operation a little over a year ago and posted details here. It is the added "impedance" that prevents the tripping.
These devices look at the high frequency content in the current being drawn. The high frequency content has to match both a certain amplitude and range in frequencies.

When you add impedance to the circuit you reduce the amplitude of the high frequency. My suggestion would always be an EMI filter located at the load!

Consider that actual and potentially dangerous arcs are also being detected using the high frequency content. If you prevent a nuisance trip are you also preventing the detection from working properly when it is most needed?

This is exactly why there should be a mandatory test done on all AFCI installations (in my opinion) to check the circuit impedance to assure that it is not too high to allow the AFCI to work properly. (If they are to be required that is). From direct testing I can tell you that the "Test Button" is not assuring proper (in-circuit) operation - an external tester could.

That makes no sense to me. If the 6' of wire is a danger, what if the circuit it self was 6' or more longer? By that logic you could only have x # ft of wire or it becomes an impedance to the AFCI.:roll:

 

[rbalex]

I think every one of those organizations stands to gain financialy from the use of AFCI devices .
Either through the installation , trouble calls , sales , or testing and certification process .

I basically gave IAEI and NASFM a pass, but with a strong enough argument you might make the case they have a financial gain. In the absense of AFCIs, I don't see any of them at genuine risk other than a loss of market.

 

[iMuse97]

Thanks everyone for your continued additions to this discussion, particularly on the actual operation of AFCI technology. It is much appreciated.

Even if it is a dead horse, I was still uninformed about certain aspects of the development of this technology. I had always compared it to the GFCI thing, and am just old enough to remember that they were a suspect technology when they first arrived, also.

 

[WIMaster]

I really do not see how any contractor is making money off of AFCIs. The warranty nuisance calls start shortly after the customer starts actually using the outlets costing the contractors $ and some customers.

Customers do not like being told that their equipment is the cause of the problem and many just plain do not believe it!
You can spend a world of time trying to explain how these things are supposed to work and showing them megger readings but they still look at you like you are some kind of demon that sold them a faulty product.
Well why does my old kirby vacuum work just fine if I plug it in here but not there, Why is it the same for my new chinese vac?, Why does the breaker trip when I change speeds on that ceiling fan but not the one in the other room??:rant::rant::rant:

Gotta go before I go ballistic.

 

[Sierrasparky]

I really do not see how any contractor is making money off of AFCIs. The warranty nuisance calls start shortly after the customer starts actually using the outlets costing the contractors $ and some customers.

Customers do not like being told that their equipment is the cause of the problem and many just plain do not believe it!
You can spend a world of time trying to explain how these things are supposed to work and showing them megger readings but they still look at you like you are some kind of demon that sold them a faulty product.
Well why does my old kirby vacuum work just fine if I plug it in here but not there, Why is it the same for my new chinese vac?, Why does the breaker trip when I change speeds on that ceiling fan but not the one in the other room??:rant::rant::rant:

Gotta go before I go ballistic.

I agree with that point.
Also did anyone notice the cost analysis that was used. Are they for real. The guy states that the increased cost to install 12 AFCI to the customer is oly about $396 based on the cost at Home Depot. What we contractors have no right to make mark-up on our materials or mark- up on our work! What these AFCI's cost nothing more to install then a regular breaker.
I think I am going to apply for non profit status and start calling my biz "the non profit sparky" :rant::rant::rant:

 

[readydave8]

If the 6' loop works, is it because now the hot is a different lenght than the neutral? (As it would be where hot & neutral hit the lite with "loop" down to wall switch).

 

[readydave8]

I don't like AFCI's, then again I used to didn't like GFCI's, at some point they stopped bothering me.

And I remember the older electricians when I was starting out that didn't like having grounds, some of them would run 12/2 plain, or cut the bare short on 12/2 wg rather than hooking it up.

But right now I __really__ don't like AFCI's.

 

[iMuse97]

I don't like AFCI's, then again I used to didn't like GFCI's, at some point they stopped bothering me.

And I remember the older electricians when I was starting out that didn't like having grounds, some of them would run 12/2 plain, or cut the bare short on 12/2 wg rather than hooking it up.

But right now I __really__ don't like AFCI's.

Good perspective. Maybe it wouldn't be good to go back to 110V services, with 4 buss fuses, and knob and tube wiring.

 

[ActionDave]

This device senses the arcs and shuts down the power to prevent a fire. This is a good thing. I think the issue that I have seen several posts about always involves universal motors. Vacuums, drill motors, Circular saws. They all have brushes they all have small arcs. As the brushes and motors age the sparks increase. The AFCI trips.
It sounds like it is doing its job....

Then you haven't seen any of of my posts. I have been fighting these things for two years. Universal motors do not trip the offending AFCI, but soft start tools do. Multiple tools, different brands of breakers, no arc in sight. Hook up my twenty five year old Skill Saw- no trip. Big blue arc that you can see in broad daylight. Hook up a tool with a soft start and it won't even make it past one cycle before the AFCI trips.