Surprised that the ark fault breaker didn?t trip

[jap]

If this was a Dental Office was it wired in Romex or Mc Cable?


JAP>

 

[jap]

And if its a Dental Office why are Arc Fault Breakers being used in the first place?

JAP>

 

[jap]

I'm sorry,,, I just realized it was just used for testing purposes but am still curious Romex or MC Cable.

JAP>

 

[MasterTheNEC]

Umm....chances are not either of those.[517.13(A)]

And just for the record...Romex is a trademark of Southwire. It is actually NM-B or Nonmetallic-Sheathed Cable to be more accurate.

 

[Dennis Alwon]

Umm....chances are not either of those.[517.13(A)]

And just for the record...Romex is a trademark of Southwire. It is actually NM-B or Nonmetallic-Sheathed Cable to be more accurate.

Are you working for southwire now. :lol: They tried to get the forum to stop using the name romex but that won't happen. For the record I do use nm cable instead. If they don't want their product advertised then I wont.

 

[GoldDigger]

At least the word SimPull (TM) has not shown any sign of going generic yet.

 

[david]

And if its a Dental Office why are Arc Fault Breakers being used in the first place?

JAP>

This circuit was not part of the exam areas and was wired using a MC run through the ceilings to the first rec. outlet NM-B for the portion of the circuit concealed.

 

[hurk27]

This all coming from memory here -neutral to ground fault will not necessarily have enough current flow to cause trip. I believe GFCI standards though do require circuitry that injects a signal in the neutral that does result in immediate trip if it faults to ground whether there is normal circuit current flow or not. AFCI with GF component don't necessarily have this feature included, and may actually need normal circuit current flow before significant current can leak to ground (probably at least 30mA) to cause the GF component to respond.

Correct, A GFCI has an extra current coil that injects a 120hz signal into the circuit to cause a trip as soon as power is supplied to the GFCI if the neutral is grounded or makes a connection to another neutral on the load side, it also causes a trip if the hot makes connection to another hot of the same phase, this was added to GFCI's sometime in the late 80's or early 90's, before this if a GFCI had a grounded neutral or it was connected to another neutral on the load side you would only get the trip after a load was turned on and cause at least .005 amps to flow on the other path, our testers would not cause this to happen which made trouble shooting GFCI's back then much harder, now AFCI's that also Incorporated a GFP (30ma) also have this problem and will not trip on a grounded neutral unless enough current is placed upon the the circuit to produce an imbalance of .030 amps which is even higher then the older GFCI's.

So what I'm trying to say is we expect a AFCI to respond the same as a GFCI when the two are not the same, just because the AFCI didn't trip with a grounded neutral doesn't mean the AFCI was defective, it could mean that not enough current was placed upon the circuit that produced enough current to cause a imbalance of .030amps

My thoughts are that the example given where the improper "Case to Neutral" connection did not trip the AFCI "ARC" Circuit Breaker was simply a fluke moment. Traditionally the AFCI's will react to improper downstream C to N connections. Without all of the actual steps taken it is hard to determine anything other than that at this point.

As stated above, a grounded neutral will not always cause a trip on a AFCI, I have had many small electronic appliances and wall worts not provide enough current to cause a AFCI to trip, even my wiggy when applied across the line and neutral will not produce enough current on the neutral to cause an imbalance of 30ma, so any time you suspect a grounded load neutral or one that is connected to another neutral path back to the source then apply a load of at least a couple amps and it should trip.

Below is a PDF on how most modern GFCI's operate, it tells about the function of the 120hz injection coil that the AFCI does not have.

 

[mbrooke]

Correct, A GFCI has an extra current coil that injects a 120hz signal into the circuit to cause a trip as soon as power is supplied to the GFCI if the neutral is grounded or makes a connection to another neutral on the load side, it also causes a trip if the hot makes connection to another hot of the same phase, this was added to GFCI's sometime in the late 80's or early 90's, before this if a GFCI had a grounded neutral or it was connected to another neutral on the load side you would only get the trip after a load was turned on and cause at least .005 amps to flow on the other path, our testers would not cause this to happen which made trouble shooting GFCI's back then much harder, now AFCI's that also Incorporated a GFP (30ma) also have this problem and will not trip on a grounded neutral unless enough current is placed upon the the circuit to produce an imbalance of .030 amps which is even higher then the older GFCI's.

So what I'm trying to say is we expect a AFCI to respond the same as a GFCI when the two are not the same, just because the AFCI didn't trip with a grounded neutral doesn't mean the AFCI was defective, it could mean that not enough current was placed upon the circuit that produced enough current to cause a imbalance of .030amps



As stated above, a grounded neutral will not always cause a trip on a AFCI, I have had many small electronic appliances and wall worts not provide enough current to cause a AFCI to trip, even my wiggy when applied across the line and neutral will not produce enough current on the neutral to cause an imbalance of 30ma, so any time you suspect a grounded load neutral or one that is connected to another neutral path back to the source then apply a load of at least a couple amps and it should trip.

Below is a PDF on how most modern GFCI's operate, it tells about the function of the 120hz injection coil that the AFCI does not have.

Thank you! This is gold. I always wondered why GFCIs tripped immediately but AFCIs were intermittent, ie only tipped after load was applied.

 

[jap]

Umm....chances are not either of those.[517.13(A)]

And just for the record...Romex is a trademark of Southwire. It is actually NM-B or Nonmetallic-Sheathed Cable to be more accurate.

He indicated the Red conductor and the White Conductor were not Landed, and that they probably didnt have any 12/2 left on the truck,which led me to beleive he was either talking about MC or "Romex".

So I did the math.

Then he verified it was MC Cable going to the first box, which is why I was asking, since the EGC would be insulated in MC Cable, but not in "Romex", which would make it harder for me to believe that the Neutral side of a receptacle was somehow mysteriously got jammed up against and EGC on the box therefore creating a return path and bypassing the Neutral.

It was starting to sound like a fabricated story to make a point like a lot of others that tend to pop up at times. but maybe not.

Just for the record good, bad, or indifferent, "Romex" is a slang name we use for NM-B or Nonmetallic-Sheathed Cable thats been used for Years. If I told someone I was going to the Supply house to get a roll of "Nonmetallic- Sheathed Cable" or NM-B, "Although politically correct", I'd probably get laughed off the Job Site or get heckled for the rest of my career. But that's just the way we talk down here.

JAP>

 

[kwired]

So what I'm trying to say is we expect a AFCI to respond the same as a GFCI when the two are not the same, just because the AFCI didn't trip with a grounded neutral doesn't mean the AFCI was defective, it could mean that not enough current was placed upon the circuit that produced enough current to cause a imbalance of .030amps

Said it better then I could - that was my main point in all of that.