Testing old wiring before arc fault protection

[romex jockey]

So now we need to put a line reactor ahead of the service or move the house further back on the property? Sounds reasonable.

And/or ask the poco for a higher impedance Xformer

~RJ~

 

[don_resqcapt19]

4. Everything is perfectly complaint, but because it's proximal to the serving Xformer, the refer motor exceeds the afci 75A mag trip.

~RJ~

The AFCI does not have a lower magnetic (instantaneous) trip than a standard breaker. The 75 amps for the AFCI is the amount of current that must be flowing in the circuit before it looks for a parallel arcing fault.

 

[mbrooke]

The AFCI does not have a lower magnetic (instantaneous) trip than a standard breaker. The 75 amps for the AFCI is the amount of current that must be flowing in the circuit before it looks for a parallel arcing fault.

I partly disagree. In the trip curves Steve posted the magnetic trip threshold begins at around 7x (105 amps), where are older none AFCI breakers were 10x and higher. Electronics then bring the trip curve down to 75amps when "arcing" is detected. In a sense an AFCI is a low mag trip breaker with signature analysis beginning only where nuisance tripping would begin from lowering the regular magnetic trip.

 

[GoldDigger]

So in theory if the current is not above either the series or parallel arc detection threshold there can be no nuisance trips from signature analysis alone.
Vacuums and refrigerators need to pull at least 7 or 8 amps to cause a trip unless there are other loads on the same circuit?

 

[don_resqcapt19]

I partly disagree. In the trip curves Steve posted the magnetic trip threshold begins at around 7x (105 amps), where are older none AFCI breakers were 10x and higher. Electronics then bring the trip curve down to 75amps when "arcing" is detected. In a sense an AFCI is a low mag trip breaker with signature analysis beginning only where nuisance tripping would begin from lowering the regular magnetic trip.

The electronics have nothing to do with the trip curve. The electronics act to open the circuit when they think it should be opened.

 

[don_resqcapt19]

So in theory if the current is not above either the series or parallel arc detection threshold there can be no nuisance trips from signature analysis alone.
Vacuums and refrigerators need to pull at least 7 or 8 amps to cause a trip unless there are other loads on the same circuit?

As I understand it, the AFCI looks for series arcs only when the current exceeds 5 amps and looks for parallel arcs only when the current exceeds 75 amps.
I would agree that if the current does not exceed those thresholds there should not be any nuisance trips from the arc signature analysis, however RF and other types of interference can cause nuisance trips.

 

[mbrooke]

The electronics have nothing to do with the trip curve. The electronics act to open the circuit when they think it should be opened.

Then how does the breaker trip? :blink: The electronics have their own response to conditions. In the case of parallel arc faults that condition begins at 75 amps. At 75 amps the electronics look for a current signature indicative of arcing. The electronics are intentionally doing what magnetic tripping can not do because a magnetic trip of 75 amps will nuisance trip some motors. Thus manufactures decided to set the magnetic trip on AFCI starting at 7x which takes care of parallel arcs exceeding over 100amps. However the blind spot between 150 amps and 75 amps is covered by the electronics. Thats the only reason why electronics are involved in branch feeder AFCIs to begin with.

 

[mbrooke]

So in theory if the current is not above either the series or parallel arc detection threshold there can be no nuisance trips from signature analysis alone.
Vacuums and refrigerators need to pull at least 7 or 8 amps to cause a trip unless there are other loads on the same circuit?

Electronics were added to AFCIs to ironically stop nuisance tripping.


Two things were discovered in mitigating parallel (high current) arc faults:


1. “breakers can be effective at mitigating arcing faults, provided the available fault current can be guaranteed to exceed the magnetic trip level of the circuit breaker by a factor of 1.25.”

2. The lowest anticipated short circuit current at a typical 120 volt receptacle is about 75 amps.

Therefore setting the magnetic trip value in a 15 or 20 amp breaker at 75 amps would stop parallel arc faults. This would work fine, provided no high inrush items are on the circuit. Something like a window AC however would cause problems with nuisance triping. Therefore the idea of a 75 amp mag trip breaker was discarded.


AFCI manufactures instead choose to lower the magnetic trip threshold to about 7x and above instead of 5x, but still be far less then older breakers starting at +20x. This would allow vacuums and window AC units to start without nuisance tripping yet still mitigate parallel arc faults over 100 amps.


To take care of arc faults between the magnetic pick up value and the lowest anticipated short circuit current of 75 amps, wave analysis technology was implemented to bridge this gap. The technology would look for current at or above 75 amps provided they had parts of their sign waving missing or distorted which would be indicative of a parallel arc fault. If no wave distortion was seen the electronics would not respond even at 90 amps letting the thermal part do its job, if there was distortion it would trip the breaker a few cycles.

A branch feeder AFCI is nothing more then a breaker meant to trip faster on a short circuit. The key that everyone needs to take away is what a parallel arc fault really is: a short circuit. Someone discovered that a short circuit takes longer to clear via thermal trip then magnetic trip and decided to re-brand/re-classify that as high current arcing a.k.a. and arc fault.

 

[mbrooke]

S

o, the UL 1699 standard for AFCIs has roughly (50) different performance tests. Once you strip away the "standard" tests done on ALL electrical devices that ensure the product is safe from shock, fire, damage, etc.; what you are left with are primarily performance tests to prevent unwanted tripping.

For instance you have:

> Overvoltage, Undervoltage, Voltage Variations & Surge Voltage Tests (Ring Wave & Combination Wave)
> Loading Condition Tests (Inrush Current, Normal Operating Arcing, Non-Sinusoidal Waveform, Cross-Talk, Multiple Load, Lamp Burnout)
> Operation Inhibition Tests (Signal Masking, EMI Filter, Line Impedance)
> Resistance to Environmental Noise Tests (Electrostatic Discharge, Electromagnetic Field, Electrical Fast Transient, Induced RF Fields)

And there are a few others.

Those conditions can not reflect every single waveform that might be encountered in the real world. Its just a very small sample.

In order for a household refrigerator or freezer to be listed to the UL 250 standard, they must also go through a series of performance tests to ensure they do not operate outside any of the parameters set within that standard while under a host of varying conditions. None of those parameters are permitted to exceed the thresholds of the unwanted tripping tests in the UL 1699 standard for AFCIs.

Yet, in the real world we still see tripping. Probably because UL doesn't test each and every fridge with each and every AFCIs under each and ever condition.

A refrigerator is nothing more that a few motor loads, lighting loads, and perhaps a few electronic loads. None of the operational characteristics of these types of loads are subject to unwanted tripping IF they perform to standard.

That is incorrect. An inverter driven compressor is far from a few electronic loads. It produces a distinct waveform that could be mistaken as arcing.

One of three issues must be occurring in order for an AFCI to trip on a branch circuit supplying an outlet connected to a refrigerator:

1. The AFCI is damaged or defective.
2. The refrigerator is damaged or defective. (Any one part or component)
3. The wiring &/or terminations are defective.

Or the AFCI makers are not aware of a new waveform signature they must take into consideration.

That's it. The rest is simple algebra.

If only those doing wave signature analysis engineering were relying on simple algebra :lol:

If the AFCI and refrigerator are to standard, the wiring is the culprit. If the AFCI and wiring are to standard, the refrigerator is the culprit. If the refrigerator and wiring are to standard, the AFCI is the culprit.

So you admit AFCIs can be a culprit?

 

[romex jockey]

a rose by any other relabeled terminology.....

a rose by any other relabeled terminology.....

AFCI trip chart



CSPC report

~RJ~

 

[mbrooke]

AFCI trip chart



CSPC report

~RJ~

Which if one reads the public comments for the 2017 NEC such an animal is still being debated:


http://www.nfpa.org/codes-and-standards/document-information-pages?mode=code&code=70&tab=nextedition


At this point to me its clear that short circuits that just happen to take more then a few cycles to clear are being re-labelled arc faults.
W

 

[romex jockey]

Who owns 110.3B ?

Who owns 110.3B ?

Anything lacking clarity is debateable Mr MBrooke.

Further, anything we as electricians install should be readily diagnosable , the manufacturer should be liable for their performance , specifications, statistical analysis , lab testings, marketing claims, etc.

Short of this , we will simply assume more threads like these, along with the blame being foisted on the consumer or installer.

This is why i would encourage anyone out there eating service calls over these devices to investigate them

Good day to all

~RJ~

 

[ptonsparky]

Anything lacking clarity is debateable Mr MBrooke.

Further, anything we as electricians install should be readily diagnosable , the manufacturer should be liable for their performance , specifications, statistical analysis , lab testings, marketing claims, etc.

Short of this , we will simply assume more threads like these, along with the blame being foisted on the consumer or installer.

This is why i would encourage anyone out there eating service calls over these devices to investigate them

Good day to all

~RJ~

Sounds like a deal for us as the end installer because every one of us has the time to do it. Non chargeable time as well. Making sure there are no wiring problems is a must but after that is it really our place to discover and tell the customer that their new $$$$ refrigerator has a problem with the LED lights and "they" are working on a solution. In the mean time keep replacing the milk and frozen goods until they let you know of the fix.

 

[romex jockey]

the man behind the curtain....

the man behind the curtain....

The NEMA complaint dept is open 24/7 Tom

They also have a AFCI Basics Training Course

Along with an ascii cornucopia of everything they are willing to tell us

~RJ~

 

[mbrooke]

Anything lacking clarity is debateable Mr MBrooke.

Further, anything we as electricians install should be readily diagnosable , the manufacturer should be liable for their performance , specifications, statistical analysis , lab testings, marketing claims, etc.

Short of this , we will simply assume more threads like these, along with the blame being foisted on the consumer or installer.

This is why i would encourage anyone out there eating service calls over these devices to investigate them

Good day to all

~RJ~

The issue is that appliance with acceptable waveforms, current leakage ect is tripping listed AFCIs. At best its either the appliance maker or AFCIs, however the issues get put on the end user. I dont see that as fair.

 

[don_resqcapt19]

Then how does the breaker trip? :blink:

The electronics activate a solenoid that moves the same trip lever that the thermal and magnetic trips do. If there is no trip command from the electronics, the breaker acts as a standard thermal magnetic breaker. The same thing happens when the electronics fail...you just have a standard thermal magnetic breaker.

The electronics have their own response to conditions. In the case of parallel arc faults that condition begins at 75 amps. At 75 amps the electronics look for a current signature indicative of arcing. The electronics are intentionally doing what magnetic tripping can not do because a magnetic trip of 75 amps will nuisance trip some motors. Thus manufactures decided to set the magnetic trip on AFCI starting at 7x which takes care of parallel arcs exceeding over 100amps. However the blind spot between 150 amps and 75 amps is covered by the electronics.

The concept of the AFCI has nothing to do with instantaneous (magnitic)tripping based on the current....it only has to do with the detection of an "arc signature" (what ever that may be, and it is different for each manufacturer). The 75 amps was selected for the electronics to start looking for an arc signature, to reduce false trips. If they set it below the 75 amps there would be even more false trips than we have now.

The current could be hundreds or even thousands of amps, but if there is no "arc signature" the electronics will do nothing. The circuit will be opened by the thermal and/or magnetic trip devices based on their curves.

If the current is below the 75 amps, the electronics do nothing but use a small amount of power.

Thats the only reason why electronics are involved in branch feeder AFCIs to begin with.

The only reason there is electronics is because you need a "smart" device to detect "arc signatures". A standard thermal magnetic breaker can only react to current, not not to "arc signatures".

 

[don_resqcapt19]

Electronics were added to AFCIs to ironically stop nuisance tripping. ....

No. They were added to create the AFCI. You can't have an AFCI without electronics. A standard breaker cannot detect "arc signatures".

 

[mbrooke]

No. They were added to create the AFCI. You can't have an AFCI without electronics. A standard breaker cannot detect "arc signatures".

I disagree. A breaker with a low enough magnetic trip will mitigate parallel arc faults.

 

[mbrooke]

The electronics activate a solenoid that moves the same trip lever that the thermal and magnetic trips do. If there is no trip command from the electronics, the breaker acts as a standard thermal magnetic breaker. The same thing happens when the electronics fail...you just have a standard thermal magnetic breaker.

I know.

The concept of the AFCI has nothing to do with instantaneous (magnitic)tripping based on the current....it only has to do with the detection of an "arc signature" (what ever that may be, and it is different for each manufacturer). The 75 amps was selected for the electronics to start looking for an arc signature, to reduce false trips. If they set it below the 75 amps there would be even more false trips than we have now.

I disagree. Electronics came about because a 75 amp magnetic trip would cause nuisance tripping. Something other then magnetic trip was needed to catch short circuit arcs.

The current could be hundreds or even thousands of amps, but if there is no "arc signature" the electronics will do nothing. The circuit will be opened by the thermal and/or magnetic trip devices based on their curves.

Correct.

If the current is below the 75 amps, the electronics do nothing but use a small amount of power.

Correct.

The only reason there is electronics is because you need a "smart" device to detect "arc signatures". A standard thermal magnetic breaker can only react to current, not not to "arc signatures".

Incorrect. Magnetic trip has been proven to mitigate parallel arc faults. This concept even stretches to the NEC.

 

[user 100]

I disagree. A breaker with a low enough magnetic trip will mitigate parallel arc faults.

Sorry, mbrooke, but don_resqcapt19 is correct.
The recognition of arc signatures is solely the job of the electronics- the magnetic trip doesn't recognize arc signatures-it only reacts to current.
And I think you may have misinterpreted him- he wasn't claiming that you need a smart device to detect arc signatures; he was saying that detection of arc signatures is only possible because of the electronics- what else in the afci detects "arc signatures"? Nothing-no electronics for arc siganature detection, so no afci-only a souped up standard cb. Note the quotations around those few words in his posts.