2020 NEC AFCI

[kwired]

My own, although again, technically student level of understanding, is the USA uses a two phase system, the two phases actually 180 degrees out of phase of each other, and the uK and Europe use a three phase system, where the phases are 120 degrees different from each other, but wiring is still basically similar. When a business is wired with three phase here, it is five wires into the residence from the electrical supplier, three lines, a neutral and a ground, or it is simply three lines into a transformer, all three lines being live, and the ground and neutral starting at the transformer rather than the utility. Slightly different from the US as most all residences have their ground, neutral and live wire go to the nearest utility transformer.

What is called two phase here, is a mostly obsolete system but some are still in use, and is mostly out in eastern US areas where you may find it. True two phase generator has two windings 90 degrees from one another, you can connect it to a "two phase motor" and not need any capacitors to create a phase shift like you do with "single phase motors".

A typical 120/240 three wire system is single phase from one end of source winding to other, and single phase from either end to the center tap. There is no way to direct connect it to an induction type motor without artificially creating phase shift in that motor to develop rotating magnetic field in that motor, which is done with capacitors or windings with different inductance, or many times combination of both.

 

[mbrooke]

The wiring should have been decent since the building, being full of rental properties, was supposed to have the wiring in each apartment checked every three to four years for insulation, polarity, etc...

and as far as the AFCI debate goes, the last study I saw seems to say the same thing, if I read it right, that most of the incidents that happened from lightning or electrical surges even when wiring was compromised by hammer strikes, usuallput themselves out, unable to catch fire within the time of the AFCI breakers, as long as the wire and ground were both properly sized in the beginning.

But here is the thing- those surges and lightning strikes will fry the electronics within AFCIs. So even if true, the the cause is also the demise.

In the UK proper loop impedance will take care of any such event. As well as a typical RCD for line to ground faults. Hence where the 75amp "arcing" pickup came from for US AFCIs.

 

[Adamjamma]

Ok. Still not too sure on difference between US three phase and UK three phase, since both create normal voltage when any of the legs are combined with the neutral or ground, and then are a higher voltage when any leg is combined with a second leg. Main difference I think is the phase degrees as USA is normally doubled for two lines, compared to UK being 120 degrees difference, or 230/400 volts rather than 120/240... if the same degrees of separation were used in the USA you would expect 120/208 rather than 120/240

but, this digresses too much from the original concerns of AFCI... though were I somehow able to use the Schneider Isobar 9 system in a USA style system, I would probably run a group of three phase breakers, the first running to the single phase runs below it, where first position of those isobars would be an RCD protecting the breakers, like the UK uses, as this seems to offer more protection with less overall RCDs... but again, I could be wrong, which is why I pose questions as I may not see something. However, the use of so many expensive breakers in the consumer unit seems time consuming if one RCD can protect five or six regular breakers, especially when the USA codes still call for a RCD outlet in the room in many cases, in a belt and suspenders method, like the UK calls for an RCD in all outdoor outlets or extension cords now.

 

[mbrooke]

Ok. Still not too sure on difference between US three phase and UK three phase, since both create normal voltage when any of the legs are combined with the neutral or ground, and then are a higher voltage when any leg is combined with a second leg. Main difference I think is the phase degrees as USA is normally doubled for two lines, compared to UK being 120 degrees difference, or 230/400 volts rather than 120/240... if the same degrees of separation were used in the USA you would expect 120/208 rather than 120/240

US 3 phase Y is the same as UK 3 phase Y- both are 120* out of phase- just the UK is double the voltage of 240/416 vs 120/208.

The difference is residential, it comes from a single phase center tap transformer in most cases. That makes 120/240 vs 120/208. 180* out of phase vs 120*. Think of UK job sites that have that 110 volt tool supply thats 55 volts to ground.

Not to confuse, but there is 120/240 3 phase delta, but that is beyond what we have in mind.

but, this digresses too much from the original concerns of AFCI... though were I somehow able to use the Schneider Isobar 9 system in a USA style system, I would probably run a group of three phase breakers, the first running to the single phase runs below it, where first position of those isobars would be an RCD protecting the breakers, like the UK uses, as this seems to offer more protection with less overall RCDs... but again, I could be wrong, which is why I pose questions as I may not see something. However, the use of so many expensive breakers in the consumer unit seems time consuming if one RCD can protect five or six regular breakers, especially when the USA codes still call for a RCD outlet in the room in many cases, in a belt and suspenders method, like the UK calls for an RCD in all outdoor outlets or extension cords now.

You bring up a good point, however in the US protecting 5 or 6 circuits with an RCD is more difficult because our "people protection" is mandated at 5ma. 6 circuits may produce a capacitance coupling (charging current) near or at 5ma. This would result in nuisance tripping when appliances are plugged in. The UK is 30ma, so its less of an issue when all circuits combined measure say 6ma and all appliances combined measure say 3ma (9ma total).

Now, if we are talking AFCIs- that would save cost- however- nuisance tripping of said AFCI would remove more circuits and make trouble shooting much more difficult. With a multi function tester its easy to narrow down a permanent ground fault somewhere on 6 circuits, but try that with a tripping AFCI where often you have no idea whats tripping it and no tool today will tell you. Yes I know Siemens has a tool, but still... Even with one circuit electricians end up making multiple house calls to find that one offending humidifier/LED bulb/vacuum/fan/TV/charger/fish tank/your pick here. Sometimes its multiple items doing it together. Other times its a device on another circuit or not even in the home itself.

 

[Adamjamma]

Thank you on both the voltage point and the point over the circuits. Perhaps we need to consider a two place version for the future, with a 30ma in the breaker panel, but the outlets then being on a tighter, 5ma setting... and a maximum of five outlets per breaker, or such?? Thus the outlet would trip faster if it is a cord or a device fault, yet the breaker would trip for a pure wiring fault? I th8nk the RCD for my lawnmower here is lower than 30 ma.... but cannot remember because I just sold it..lol...

 

[mbrooke]

Thank you on both the voltage point and the point over the circuits. Perhaps we need to consider a two place version for the future, with a 30ma in the breaker panel, but the outlets then being on a tighter, 5ma setting... and a maximum of five outlets per breaker, or such?? Thus the outlet would trip faster if it is a cord or a device fault, yet the breaker would trip for a pure wiring fault? I th8nk the RCD for my lawnmower here is lower than 30 ma.... but cannot remember because I just sold it..lol...

If they mandated differential protection instead of AFCIs not not only would we have equal or better protection (half of new AFCIs do not even have GFP) but all the nuisance tripping would disappear.

 

[romex jockey]

Objectively , what is the dif betwixt a differential and afci?
Isn't the chief operation component a toroidal for both?

~RJ~

 

[kwired]

Objectively , what is the dif betwixt a differential and afci?
Isn't the chief operation component a toroidal for both?

~RJ~

Might be main component, but also is for a GFCI. What you do with what is being measured by that component is what makes them all different.

 

[romex jockey]

My experiences are all GF, save for GE's which never seem to trip, which is why I use them

But I digress

To understand how they pass UL's simulator is to understand their true functionality better

~RJ~

 

[GoldDigger]

Objectively , what is the dif betwixt a differential and afci?
Isn't the chief operation component a toroidal for both?

~RJ~

The GFCI runs both wires through a toroid and looks for a difference signal.
The AFCI uses a toroid to measure current, since it must disable series arc trips below about 7 amps and parallel arc trips below about 60A. This is to reduce false tripping from signals from that circuit or another circuit from the same source. The signal it is looking for is an RF voltage and/or current caused by an electric arc. It cannot detect an ohmic fault (aka glowing connection).

Sent from my XT1585 using Tapatalk

 

[romex jockey]

I would encourage anyone interested to try this>>>


https://youtu.be/iLmC5quELrE

~RJ~

 

[kwired]

I would encourage anyone interested to try this>>>


https://youtu.be/iLmC5quELrE

~RJ~

I have seen that clip before. I think it didn't trip because the breaker was installed with down position of the handle being the "on" position

 

[Tony S]

mbrooke: Sorry, that 120V does not sustain an arc is not correct: 120V carbon electrode arc lamps were used in projectors of movie theatres in the past!

Sahib, theatre arc lamps used DC
__________________________________________________________

This thread has been interesting reading. As many of you know Arc Fault Detection Devices (AFCI) are to be included as a recommendation in the 18^th edition of BS7671 despite fierce opposition. Our argument against AFDD’s was based on our different wiring methods and the use of BS1363 fused plugs and tamper proof sockets. The plug top fuses are BS1361.

BS1361 fused plugs aren’t infallible, my kettle committed suicide, it took both the fuse and the 32A B curve MCB.

When the 18^th is issued RCD’s will be required on all circuits. RCD’s on lighting circuits isn’t a popular decision.

Unlike NFPA-NEC, BS7671 is not statute law, but if you find yourself in front of the man in a wig it will be used to prosecute you.

 

[romex jockey]

Hi Tony

I'm confused, does BS7671 mean some sort of afci RCD has debuted across the pond?


~RJ~

 

[mbrooke]

Sahib, theatre arc lamps used DC
__________________________________________________________

This thread has been interesting reading. As many of you know Arc Fault Detection Devices (AFCI) are to be included as a recommendation in the 18^th edition of BS7671 despite fierce opposition. Our argument against AFDD’s was based on our different wiring methods and the use of BS1363 fused plugs and tamper proof sockets. The plug top fuses are BS1361.

BS1361 fused plugs aren’t infallible, my kettle committed suicide, it took both the fuse and the 32A B curve MCB.

When the 18^th is issued RCD’s will be required on all circuits. RCD’s on lighting circuits isn’t a popular decision.

Unlike NFPA-NEC, BS7671 is not statute law, but if you find yourself in front of the man in a wig it will be used to prosecute you.

Oh Tony, if people only knew the truth- that UL and friends were using BS7671 as the cook book when concocting the theory of arcing and AFCIs. Nothing is original thought.


In your kettle incident, that just means the short circuit current went above the magnetic trip threshold of your MCB. The plug fuse is there in case it does not.

 

[TangentJimT]

Advances in technology

Advances in technology

I wonder how many detractors of AFCI's have actually experienced nuisance tripping. I for one am absolutely convinced that the original arc fault circuit interrupter and the more advanced combination arc fault circuit interrupter were huge advancements and that the combination GFCI/CAFCI requirement will one of the greatest advancements to date in residential electrical safety protection.

I recently had dealings with a real estate investor who had purchased a 1978 home for rental that had been owned for years by a do-it-yourself "handyman". There were many obvious electrical conditions that led me to worry about hidden concerns. I felt there were two options for the owner to consider - either trace every circuit in the home and open every device and junction box (hoping none were buried behind drywall) or install a modern distribution panel with combination GFCI/CAFCI circuit breakers. I was very concerned that there were likely areas where connections behind the drywall may not be in junction boxes and that the only way to be absolutely sure would be to strip the walls and ceilings, certainly not an option financially.

I'll admit to a prejudice that grew out of having recently watched as my son and his wife and children stood by helplessly seeing their 1976 home burn to the ground as a result of an electric fire. They lost everything they owned.

The investor took my advice and elected to go with the new panel and combo breakers. Yes, some issues arose right away, but on 3 circuits only. These were traced down, aided by the sequential light signals that allowed the causes to be narrowed down. Primarily, they were combined neutrals in various boxes, but the point is the home is now safe. Ground faults? Covered. Arc faults? Covered.

I do not believe this is a result of lobbying, it is a result of dramatic advancements in technology that any thinking person should at least consider as life-saving achievements. Will some individuals have to sharpen their skills? Perhaps, but those who find they must should have sharpened them ages ago. I wonder how many "nuisance trips" have turned out to be the result of loose terminations? How many electricians carry (and use) torque screwdrivers? Thank goodness for the engineers, manufacturers and the NEC for the CAFCI and the combination GFCI/CAFCI circuit breaker.

 

[romex jockey]

I'll admit to a prejudice that grew out of having recently watched as my son and his wife and children stood by helplessly seeing their 1976 home burn to the ground as a result of an electric fire. They lost everything they owned.

.

Welcome to MH's Jim.

You'll find many tenured sparks here, many were (some still are) also FF's

Having watched those that 'loose everything' does move one towards a vested interest

But the devil is always in the details, so i would encourge you read this, from it's inventor>

http://www.combinationafci.com/resources/doc_ieee_combination_afci.pdf

~RJ~

 

[retirede]

I wonder how many detractors of AFCI's have actually experienced nuisance tripping. I for one am absolutely convinced that the original arc fault circuit interrupter and the more advanced combination arc fault circuit interrupter were huge advancements and that the combination GFCI/CAFCI requirement will one of the greatest advancements to date in residential electrical safety protection.

I recently had dealings with a real estate investor who had purchased a 1978 home for rental that had been owned for years by a do-it-yourself "handyman". There were many obvious electrical conditions that led me to worry about hidden concerns. I felt there were two options for the owner to consider - either trace every circuit in the home and open every device and junction box (hoping none were buried behind drywall) or install a modern distribution panel with combination GFCI/CAFCI circuit breakers. I was very concerned that there were likely areas where connections behind the drywall may not be in junction boxes and that the only way to be absolutely sure would be to strip the walls and ceilings, certainly not an option financially.

I'll admit to a prejudice that grew out of having recently watched as my son and his wife and children stood by helplessly seeing their 1976 home burn to the ground as a result of an electric fire. They lost everything they owned.

The investor took my advice and elected to go with the new panel and combo breakers. Yes, some issues arose right away, but on 3 circuits only. These were traced down, aided by the sequential light signals that allowed the causes to be narrowed down. Primarily, they were combined neutrals in various boxes, but the point is the home is now safe. Ground faults? Covered. Arc faults? Covered.

I do not believe this is a result of lobbying, it is a result of dramatic advancements in technology that any thinking person should at least consider as life-saving achievements. Will some individuals have to sharpen their skills? Perhaps, but those who find they must should have sharpened them ages ago. I wonder how many "nuisance trips" have turned out to be the result of loose terminations? How many electricians carry (and use) torque screwdrivers? Thank goodness for the engineers, manufacturers and the NEC for the CAFCI and the combination GFCI/CAFCI circuit breaker.

Nuisance tripping is only a minor issue.
The real issues are:
1) the majority of electrical fires are cause by faulty or improperly operated utilization equipment, not permanent wiring problems.
2) Most fires attributed to permanent wiring are caused by glowing connections, not series arc faults.
3) Arc fault devices don’t do what they are designed for reliably. You can find a number of videos online demonstrating series arcs that do not trip the AFCI.

Bottom line, even if they worked, they would not prevent most electrical fires (1&2), plus they don’t work.

 

[hbiss]

I wonder how many detractors of AFCI's have actually experienced nuisance tripping. I for one am absolutely convinced that the original arc fault circuit interrupter and the more advanced combination arc fault circuit interrupter were huge advancements and that the combination GFCI/CAFCI requirement will one of the greatest advancements to date in residential electrical safety protection.

I recently had dealings with a real estate investor who had purchased a 1978 home for rental that had been owned for years by a do-it-yourself "handyman". There were many obvious electrical conditions that led me to worry about hidden concerns. I felt there were two options for the owner to consider - either trace every circuit in the home and open every device and junction box (hoping none were buried behind drywall) or install a modern distribution panel with combination GFCI/CAFCI circuit breakers. I was very concerned that there were likely areas where connections behind the drywall may not be in junction boxes and that the only way to be absolutely sure would be to strip the walls and ceilings, certainly not an option financially.

I'll admit to a prejudice that grew out of having recently watched as my son and his wife and children stood by helplessly seeing their 1976 home burn to the ground as a result of an electric fire. They lost everything they owned.

The investor took my advice and elected to go with the new panel and combo breakers. Yes, some issues arose right away, but on 3 circuits only. These were traced down, aided by the sequential light signals that allowed the causes to be narrowed down. Primarily, they were combined neutrals in various boxes, but the point is the home is now safe. Ground faults? Covered. Arc faults? Covered.

I do not believe this is a result of lobbying, it is a result of dramatic advancements in technology that any thinking person should at least consider as life-saving achievements. Will some individuals have to sharpen their skills? Perhaps, but those who find they must should have sharpened them ages ago. I wonder how many "nuisance trips" have turned out to be the result of loose terminations? How many electricians carry (and use) torque screwdrivers? Thank goodness for the engineers, manufacturers and the NEC for the CAFCI and the combination GFCI/CAFCI circuit breaker.

Unfortunately I believe your position is based on emotion and ignorance. You really have no experience or formal knowledge of AFCI technology to reach the conclusion you have. We have literally hundreds of years of combined knowledge of the electrical field on this board as well as actual members of the NEC CMPs.

Believe me when I say that if AFCI technology were proven viable and worked to save lives we would all embrace it with open arms. Sadly that is not the case and it remains as much smoke and mirrors today as it was when it was adopted. I believe that the only reason we still have it today is because if manufacturers pulled the plug now it would be an admission of the fraud they committed and that would open them up to multi-billion dollar lawsuits.

Further, IMO you gave your real estate investor bad advice and a false sense of security based on your lack of knowledge and position as a home inspector. His concerns should have been addressed by a licensed electrical contractor who would have done a thorough evaluation.

How would you feel if that house had a fire and someone in his family died?

-Hal

 

[romex jockey]

I believe that the only reason we still have it today is because if manufacturers pulled the plug now it would be an admission of the fraud they committed and that would open them up to multi-billion dollar lawsuits.

-Hal

A number of class action lawsuits fizzeled out before they ever entered a courtroom Hal

~RJ~