AFCI Breakers

[bphgravity]

Guys. Its only one of (4) tests. This particular test simulates a common event that occurs in cord-and-plug connected equipment downstream from other connected loads. A common example would be furniture that has been unintentionally placed on a flexible cord or pushed up against a wall where cord-and-lug connected equipment is plugged into a receptacle outlet.

A series cut in one conductor is simulated in one of the other tests.

There is no "what if I" scenario. There are two series tests, there are two parallel tests. PERIOD.

 

[mbrooke]

Guys. Its only one of (4) tests. This particular test simulates a common event that occurs in cord-and-plug connected equipment downstream from other connected loads. A common example would be furniture that has been unintentionally placed on a flexible cord or pushed up against a wall where cord-and-lug connected equipment is plugged into a receptacle outlet.

A series cut in one conductor is simulated in one of the other tests.

There is no "what if I" scenario. There are two series tests, there are two parallel tests. PERIOD.

Then why is this:

[FONT=&quot]b) The insulation across both wires is to be slit 2 inches (50.8
mm) from one end to a depth to expose the conductors
without severing any strands.[/FONT]

In series like this:

 

[mbrooke]

When in the real world arcing in series with a load takes place like this, to the right, only involving one side of the cord:

 

[growler]

Guys. Its only one of (4) tests. This particular test simulates a common event that occurs in cord-and-plug connected equipment downstream from other connected loads. A common example would be furniture that has been unintentionally placed on a flexible cord or pushed up against a wall where cord-and-lug connected equipment is plugged into a receptacle outlet.

A series cut in one conductor is simulated in one of the other tests.

There is no "what if I" scenario. There are two series tests, there are two parallel tests. PERIOD.

No one doubts that an AFCI will pass the test. What is in doubt is if the test simulate the real world.

A appliance cord or lamp cord in the US is 6 ft. in length. If receptacles are properly placed a lamp is sitting on a table with very little length left over to worry about. In older homes with fewer receptacles it was common to have an extension cord plugged in to a receptacle some distance from a lamp. These cords tend to be behind or under furnature.

So now I sell an AFCI breaker to a homeowner telling them that it will protect against series arcs. Will it?

Say the lamp has two 75 bulbs (lamps) for a load of less than 1.5 amps.

 

[wwhitney]

But in the UL test preparation of the zip is not a series cut, rather both the neutral and line conductors have the insulation removed.

In the UL test, the cord specimen is cut across both conductors. Effectively the conductors on one side of the cut are unused, the current path is from the first half of conductor A to the first half of conductor B to the load. Even though conductors A and B in the first half of the zip wire are physically in parallel, they are electrically in series.

They could have just taken the zip wire, separated the two conductors and thrown one away, cut the remaining conductor in half, taped together the two halves one alongside the other with their cut ends adjoining, and then done their carbonization. Why didn't they design the test that way? I'm guessing, maybe the way they designed it is more repeatable.

Don't get me wrong, I'm no fan of AFCIs based on a preponderance of the evidence presented. I just think this particular criticism isn't on point.

Cheers, Wayne

 

[mbrooke]

In the UL test, the cord specimen is cut across both conductors. Effectively the conductors on one side of the cut are unused, the current path is from the first half of conductor A to the first half of conductor B to the load. Even though conductors A and B in the first half of the zip wire are physically in parallel, they are electrically in series.

They could have just taken the zip wire, separated the two conductors and thrown one away, cut the remaining conductor in half, taped together the two halves one alongside the other with their cut ends adjoining, and then done their carbonization. Why didn't they design the test that way? I'm guessing, maybe the way they designed it is more repeatable.

Don't get me wrong, I'm no fan of AFCIs based on a preponderance of the evidence presented. I just think this particular criticism isn't on point.

Cheers, Wayne

Why cant they just cut one side of the zip cord breaking the insulation and copper without damaging the other side, then tapping it up. They did it with the NM. This is how series faults look like in the real world.

Perhaps you said it: "I'm guessing, maybe the way they designed it is more repeatable." And perhaps a more reliable way to obtain arcing because in the real world a series fault may not present the same level of sustained arcing.

 

[bphgravity]

Why cant they just cut one side of the zip cord breaking the insulation and copper without damaging the other side, then tapping it up. They did it with the NM. This is how series faults look like in the real world.

Because this is a different test. The arc ignition test simulates damage to the branch circuit wiring between the AFCI device and the load which is typically NM cable in a wall. This is clearly a series test.

The arc clearing time test simulates damage to a flexible cord downstream of the AFCI device and load. This too is a series test.

This is what differentiates branch/feeder type devices from combination type devices:

BRANCH/FEEDER ARC-FAULT CIRCUIT-INTERRUPTER – A device intended to be installed at the origin of a branch circuit or feeder, such as at a panelboard. It is intended to provide protection of the branch circuit wiring, feeder wiring, or both, against unwanted effects of arcing. This device also provides limited protection to branch circuit extension wiring. It may be a circuit-breaker type device or a device in its own enclosure mounted at or near a panelboard.

COMBINATION ARC-FAULT CIRCUIT-INTERRUPTER – An AFCI which complies with the requirements for both branch/feeder and outlet circuit AFCIs. It is intended to protect downstream branch circuit wiring and cord sets and power-supply cords.

 

[mbrooke]

Because this is a different test. The arc ignition test simulates damage to the branch circuit wiring between the AFCI device and the load which is typically NM cable in a wall. This is clearly a series test.

The arc clearing time test simulates damage to a flexible cord downstream of the AFCI device and load. This too is a series test.

This is what differentiates branch/feeder type devices from combination type devices:

So all of them are classified as series?

I am well aware the UL tests call it a series test because the current is limited through a load, but in the real world such current would not be limited when two conductors are damaged and in turn would be classified as parallel.

 

[wwhitney]

I am well aware the UL tests call it a series test because the current is limited through a load

Yes.

but in the real world such current would not be limited when two conductors are damaged and in turn would be classified as parallel.

Yes, in the real world damage to the two current carrying conductors in an appliance cord would likely lead to parallel arcing.

But the test is not using the zip cord as two current carrying conductors. It is using it as a single conductor, and you can't have parallel arcing within a single conductor. Maybe using zip cord as a single conductor is a goofy way to simulate series arcing, but it is a series test, not a parallel test.

As for why they don't just duplicate the NM cable series test with the zip cord, I'm guessing again, but maybe that wouldn't be very useful. The test would be very similar, maybe duplicative. With the zip cord series test they use, the copper gap is quite a bit bigger than in the NM cable series test.

Cheers, Wayne

 

[romex jockey]

afci series testing.....

afci series testing.....

Shown in Fig, 13 is a photo taken during one such test.
Smoke and flames are shown coming from the fiberglass tape,
see step c. The tape is a UL Recognized component, often
used by electricians to cover electrical connection.

The smoke and fire surprised the author, so he ran a simple
flammability test on a piece of fiberglass electrical tape, see
Fig. 14.

The tape is obviously VERY flammable and its use to cover
electrical connections is probably not wise. Also using it as
part of UL 1699 is hard to explain.

just add killivolts ......:lol:

~RJ~

 

[user 100]

But we can sell AFCI's for $40-60 and someday we may get them to do everything we want, those plug top fuses may only be a quarter to a dollar

Then how would one guarantee that the unqualified wouldn't replace the end caps, thus defeating the whole purpose? Would we then make replacement standard cord caps unobtainable for the general public? Confiscate the reels down at HD?

 

[mivey]

And if I took the same cord specimen and plugged it into a 120 volt outlet, is there a load still in series?

If you plugged it in between the AFCI and variable load. The arrangement is a series test. You are just not looking at it right. The fact that the conductors are arranged side by side vs. end to end has no bearing. I can't imagine the difference in contact area makes a difference.

 

[mivey]

There are two series tests, there are two parallel tests. PERIOD.

I agree. If you look at the test arrangements it is clear.

 

[mivey]

So now I sell an AFCI breaker to a homeowner telling them that it will protect against series arcs. Will it?

Say the lamp has two 75 bulbs (lamps) for a load of less than 1.5 amps.

In a future code cycle all circuits and cords will be required to carry more than 5 amps of load at all times.

 

[mivey]

Why cant they just cut one side of the zip cord breaking the insulation and copper without damaging the other side, then tapping it up. They did it with the NM. This is how series faults look like in the real world.

They could have. Not sure what significant difference it would make. Perhaps they needed more surface area to get the results they wanted in the lab.

What happens in the real world is not the same as what has to happen per the standard. Contrive a test that you can pass, put it in a standard, then everybody's heads nod happily when the mouse runs the maze whether or not the maze is a real world path.

 

[GoldDigger]

They could have. Not sure what significant difference it would make. Perhaps they needed more surface area to get the results they wanted in the lab.

What happens in the real world is not the same as what has to happen per the standard. Contrive a test that you can pass, put it in a standard, then everybody's heads nod happily when the mouse runs the maze whether or not the maze is a real world path.

It is easier to specify one process for getting a sustainable arc in a piece of zip cord and use that same process to prepare the arc segment that is used in both series and parallel tests. Surface area, etc. may not be relevant.

 

[romex jockey]

imagination at work....

imagination at work....

~RJ~

 

[mbrooke]

Then how would one guarantee that the unqualified wouldn't replace the end caps, thus defeating the whole purpose? Would we then make replacement standard cord caps unobtainable for the general public? Confiscate the reels down at HD?

How do we know unqualified aren't going to take AFCI out? Heck the qualified are taking them out :lol:

 

[mbrooke]

They could have. Not sure what significant difference it would make. Perhaps they needed more surface area to get the results they wanted in the lab.

What happens in the real world is not the same as what has to happen per the standard. Contrive a test that you can pass, put it in a standard, then everybody's heads nod happily when the mouse runs the maze whether or not the maze is a real world path.

I think so. A true series test might not produce the results intended.

 

[don_resqcapt19]

~RJ~

How old is that information? GE no longer has a GFP circuit in their AFCIs and item 2 suggests that GFP sometimes clears the series arc.