2017 NEC AFCI

[mbrooke]

The development of 2017 NEC is far from being complete, so I wouldn't get too worked-up over the Second Draft Reports. Receipt for recirculation of voting doesn't occur until January 22, 2016. The Correlating Committee doesn't meet until February. Things can change!

NITNAM filings are accepted until April 29, 2016. Assembly voting occurs at the annual meeting in June. And, appeals can be submitted as late as July 2016.

So, a lot can happen between now and the publication of the 2017 NEC.

This may even be an issue that gets a TIA issuance...

So, stay tuned!

I am begging, and I mean begging that Furnaces/boilers be exempt from AFCI requirements. Nuisance tripping will cost everything.

 

[mbrooke]

I knew the series arc thing but did not realize the afci was not going to detect a glowing connection due to a diminished diameter conductor.

A glowing connection is simply restive heating through poor conductivity. Any sparking will only take place if a complete break occurs during the event, which is usually toward the end when the connection is finally disintegrating from glowing red/white hot.

 

[ActionDave]

I am begging, and I mean begging that Furnaces/boilers be exempt from AFCI requirements. Nuisance tripping will cost everything.

To exempt them means admitting AFCIs have a problem.

 

[GoldDigger]

Actually, leaving out the GFCI component might be a good idea for a furnace with flame sensor(s).

 

[mbrooke]

Actually, leaving out the GFCI component might be a good idea for a furnace with flame sensor(s).

But not VFD motors.

 

[flatlander]

The development of 2017 NEC is far from being complete, so I wouldn't get too worked-up over the Second Draft Reports. Receipt for recirculation of voting doesn't occur until January 22, 2016. The Correlating Committee doesn't meet until February. Things can change!

NITNAM filings are accepted until April 29, 2016. Assembly voting occurs at the annual meeting in June. And, appeals can be submitted as late as July 2016.

So, a lot can happen between now and the publication of the 2017 NEC.

This may even be an issue that gets a TIA issuance...

So, stay tuned!

What is a TIA

 

[user 100]

What is a TIA

TIA: Tentative interim amendment.

It's supposedly something to do with making changes to the code between cycles- deleting, modifying, etc.

 

[flatlander]

Thanks

 

[flatlander]

Hey I was doing some reading and I am now thoroughly confused.
If this new wording is finally approved how do the OBC devices handle parallel faults up stream. If I recall correctly a branch circuit afci handled this where a regular breaker could not. If it did the we would not have the first generation afci.

Or are we back to the theory we were lied to by the breaker manufacturer's.

 

[peter d]

I am begging, and I mean begging that Furnaces/boilers be exempt from AFCI requirements. Nuisance tripping will cost everything.

I'm not begging for anything, I simply won't install them.

 

[mbrooke]

I'm not begging for anything, I simply won't install them.

Now your thinking, please do. :thumbsup: The world would be a lot better place if people spoke up. I personally feel that all electricians and inspectors should refuse to enforce installation of AFCIs. I feel sorry for the countless inspectors and electricians who are being taken for a ride by this fraud. Just because I may not understand something to the fullest or have your complete trust does not mean you can take advantage of me as we have seen happen here.

 

[iwire]

I'm not begging for anything, I simply won't install them.

:lol:

A true rebel.

Of course you will if you work for someone.

 

[peter d]

:lol:

A true rebel.

Of course you will if you work for someone.

Maybe yes, maybe not. Believe me, I know contractors who remove them if they nuisance trip. I may have even worked for one.

 

[kwired]

30 years old. One instance a #8 aluminum reduced to about a 12. And still working.

That is not a series arc until it breaks apart though, and should appear to the circuit as nothing more then a resistor within the circuit. Resistance is a common desired component in almost all circuits, yet resistance in the wrong place is undesired, how is the AFCI supposed to know when resistance is desired and not desired?

 

[kwired]

Hey I was doing some reading and I am now thoroughly confused.
If this new wording is finally approved how do the OBC devices handle parallel faults up stream. If I recall correctly a branch circuit afci handled this where a regular breaker could not. If it did the we would not have the first generation afci.

Or are we back to the theory we were lied to by the breaker manufacturer's.

I believe someone mentioned lowering the magnetic trip setting on "standard" circuit breakers as being an important part of this. Thing is some breakers already had lower magnetic trip setting years before AFCI was introduced and likely already took care of parallel arc faults. In particular Square D's QO series in the 15 and 20 amp single pole units. Those two are available in a "high magnetic trip" model for situations where the standard device will not hold starting current for certain items, but otherwise the standard device does trip at lower instantaneous current then most competitors breakers do.

 

[mbrooke]

I believe someone mentioned lowering the magnetic trip setting on "standard" circuit breakers as being an important part of this. Thing is some breakers already had lower magnetic trip setting years before AFCI was introduced and likely already took care of parallel arc faults. In particular Square D's QO series in the 15 and 20 amp single pole units. Those two are available in a "high magnetic trip" model for situations where the standard device will not hold starting current for certain items, but otherwise the standard device does trip at lower instantaneous current then most competitors breakers do.

It was, because the theory was formulated that if a short circuit or ground fault does not trip the breaker within a few cycles it will lead to fire. Of course, this has yet to be proven.

 

[flatlander]

I believe someone mentioned lowering the magnetic trip setting on "standard" circuit breakers as being an important part of this. Thing is some breakers already had lower magnetic trip setting years before AFCI was introduced and likely already took care of parallel arc faults. In particular Square D's QO series in the 15 and 20 amp single pole units. Those two are available in a "high magnetic trip" model for situations where the standard device will not hold starting current for certain items, but otherwise the standard device does trip at lower instantaneous current then most competitors breakers do.

Ok for discussion. How does that work with the current supply of breakers if the requirement is removed to have a listed pair.

 

[mbrooke]

Ok for discussion. How does that work with the current supply of breakers if the requirement is removed to have a listed pair.

My understanding is that the listed pair was nothing more then a thermal magnetic breaker with a known magnetic trip level around 300 to 500amps. UL however did test if modern circuit breakers could do the same and to what degree:

http://newscience.ul.com/wp-content...lity_to_Mitigate_Parallel_Arcing_Faults_1.pdf

http://newscience.ul.com/wp-content...lity_to_Mitigate_Parallel_Arcing_Faults_2.pdf

http://www.ul.com/global/documents/library/white_papers/BreakerMitigationofArcFaults.pdf

In testing it appears UL discovered that all modern single pole 15 and 20amp circuit breakers trip magnetically at around 10x the handle rating. This is because in the the late 80s / early 90s manufactures decided to lower the magnetic trip thresholds of single pole breakers then ranging anywhere from 12 to 42x down to around 10x. QO has always been an exception with a magnetic trip around 7-9x.

With trip values now known of modern breakers it was concluded that when coupled with the lowest anticipated available fault current from a POCO (about 500amps) these breakers will trip magnetically on a short circuit with up to 50 feet of NM cable.

Therefore, under worse case scenario it can be guaranteed all modern installations will trip a breaker magnetically when a short circuit occurs at 50 feet or less from the panel board on branch circuit. Thus, this section is considered to have parallel arc fault protection.

I know, mag trip does the same what complex electronics are doing :lol: I will go into that latter.

 

[mbrooke]

Supporting documentation for the above:



https://www.cpsc.gov//PageFiles/108737/AFCIFireTechnology.pdf


From page 8:

Lowering the Instantaneous Trip Level of Circuit Breakers

A 1992 study18 sponsored by the Electronic Industries Association (EIA) was
conducted by UL to determine if the instantaneous trip level of conventional circuit
breakers could be significantly reduced. The purpose of reducing the instantaneous
threshold was to mitigate the effects of arcing faults in extension and power cords used
with appliances in residences. Tests were conducted on 1,590 receptacles in 80 residences
to determine the available short-circuit current in 15 A and 20 A receptacles. Plot A in
Figure 1 is a distribution of the estimated short-circuit current available versus the
percentage of circuits having sufficient fault current to trip a breaker. Plot B in Figure 1 is
the short-circuit current with 6 feet of No. 18 AWG appliance cord plugged into the
receptacle being tested. The average available short-circuit current in surveyed residences
at receptacles in 15 A branch circuits was 300 A. The average available short-circuit
current at receptacles in 20 A branch circuits was 467 A.

Page 9

Figure 1 shows that 100 percent of the receptacles surveyed had over 75 A
available short circuit current. The ability of the circuit breaker to trip depends on the
instantaneous trip level of the installed circuit breaker and the available short-circuit
current. A 15 A circuit breaker with a 150 A instantaneous trip level should trip with a
short-circuit fault in 84 percent of the receptacles surveyed. However, for a fault at the
end of a 6-foot No. 18 AWG appliance cord plugged into the receptacle, the available
fault current at only 78 percent of the receptacle locations would be sufficient to trip a 15
A circuit breaker. Similarly, a 15 A circuit breaker with a 195 A instantaneous trip level
would trip with a short circuit fault in 69 percent of the receptacles surveyed. With a fault
at the end of a 6-foot appliance cord plugged into the receptacle, the breaker would trip
only 56 percent of the receptacles.

 

[flatlander]

My understanding is that the listed pair was nothing more then a thermal magnetic breaker with a known magnetic trip level around 300 to 500amps. UL however did test if modern circuit breakers could do the same and to what degree:

http://newscience.ul.com/wp-content...lity_to_Mitigate_Parallel_Arcing_Faults_1.pdf

http://newscience.ul.com/wp-content...lity_to_Mitigate_Parallel_Arcing_Faults_2.pdf

http://www.ul.com/global/documents/library/white_papers/BreakerMitigationofArcFaults.pdf

In testing it appears UL discovered that all modern single pole 15 and 20amp circuit breakers trip magnetically at around 10x the handle rating. This is because in the the late 80s / early 90s manufactures decided to lower the magnetic trip thresholds of single pole breakers then ranging anywhere from 12 to 42x down to around 10x. QO has always been an exception with a magnetic trip around 7-9x.

With trip values now known of modern breakers it was concluded that when coupled with the lowest anticipated available fault current from a POCO (about 500amps) these breakers will trip magnetically on a short circuit with up to 50 feet of NM cable.

Therefore, under worse case scenario it can be guaranteed all modern installations will trip a breaker magnetically when a short circuit occurs at 50 feet or less from the panel board on branch circuit. Thus, this section is considered to have parallel arc fault protection.

I know, mag trip does the same what complex electronics are doing :lol: I will go into that latter.

not being sarcastic. So what. What is the relevance. The proposed code does not take into account the breakers already out in the field.

Then there is the question "why did we have the branch circuit AFCI if these new breakers are just fine "

sorry don't buy it. Just furthers my opinion the afci is a mostly a fraud.