Ravenvalor
Senior Member
- Location
- Piedmont region of NC
Does anyone have any tips on how to troubleshoot an AFCI circuit with a meggohmmeter?
Thanks,
Jim
Thanks,
Jim
AFCI troubleshooting
- Thread starter Ravenvalor
- Start date
- Status
cadpoint
Senior Member
- Location
- Durham, NC
Well you can't meg a AFGI circuit breaker you'll smoke the insides ...
Siemens has a trouble shooting page based on their product at Siemens
They have a three different down loadable(s),
Trouble shooting White Paper,
AFCI Trouble shooting guide
AFCI trouble shooting Outline
Siemens
I was given their card at a trade lunch the e-address as shown on this card is no longer correct.
I'm sure that other major brands have their respective information and support up for their respective products,
But they didn't give out business cards yet!
Siemens has a trouble shooting page based on their product at Siemens
They have a three different down loadable(s),
Trouble shooting White Paper,
AFCI Trouble shooting guide
AFCI trouble shooting Outline
Siemens
I was given their card at a trade lunch the e-address as shown on this card is no longer correct.
I'm sure that other major brands have their respective information and support up for their respective products,
But they didn't give out business cards yet!
Last edited:
mdshunk
Senior Member
- Location
- Right here.
That's why he wants to check the circuit, not the breaker.
cadpoint
Senior Member
- Location
- Durham, NC
I answered it the way they wrote the question, and anyone thats done enough reading here can surely remember that stranger things have happened!
"Q" stated it perfectly that, "I'm not here to fix forty years of Kin, Hack, and Truckslammer work trying to install a AFCI !"
OP please meggar the Circuit, not the AFCI, thanks Mark !
"Q" stated it perfectly that, "I'm not here to fix forty years of Kin, Hack, and Truckslammer work trying to install a AFCI !"
OP please meggar the Circuit, not the AFCI, thanks Mark !
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
081129-1012 EST
Ravenvalor:
What do you want to troubleshoot? The AFCI or the circuit connected to the AFCI?
There is probably no practical way for you to troubleshoot the AFCI. Or to even determine if it works correctly. Or if it is related to your circuit problems.
To meg your circuit disconnect the circuit from the AFCI. Remove all loads from the circuit. Do not assume that a TV is disconnected because it is off. Physically unplug or otherwise disconnect every load. Now you can meg your circuit.
Now suppose the reason you want to meg the circuit is because the AFCI was tripping. Megging the circuit may not indicate whether the circuit is at fault for tripping, or a load, or a false trip.
Maybe the question you want to ask is how to troubleshoot a circuit for a cause of AFCI tripping.
.
Ravenvalor:
What do you want to troubleshoot? The AFCI or the circuit connected to the AFCI?
There is probably no practical way for you to troubleshoot the AFCI. Or to even determine if it works correctly. Or if it is related to your circuit problems.
To meg your circuit disconnect the circuit from the AFCI. Remove all loads from the circuit. Do not assume that a TV is disconnected because it is off. Physically unplug or otherwise disconnect every load. Now you can meg your circuit.
Now suppose the reason you want to meg the circuit is because the AFCI was tripping. Megging the circuit may not indicate whether the circuit is at fault for tripping, or a load, or a false trip.
Maybe the question you want to ask is how to troubleshoot a circuit for a cause of AFCI tripping.
.
Ravenvalor
Senior Member
- Location
- Piedmont region of NC
AFCI tripping
AFCI tripping
Thanks for the responses.
A customer's AFCI breaker keeps tripping. After searching on this website I noticed Marc once stating that he uses a meggohmeter to troubleshoot AFCI protected circuits. So I thought I would start a thread dedicated solely with using a meggohmeter to troubleshoot AFCI protected circuits.
I think he uses the meter to look for shorts in between the neutral and ground. If this is so, why not just use a regular ohmmeter? Does a megger's several hundred volts of dc current reveal problems otherwise invisible with an ohmmeter. I built a tesla coil a couple of years ago and somewhat understand insulation breakdown on a 100k volt scale. I have not had any experience with insulation breakdown on a smaller voltage scale before. I have been in the electrical business for 22 years now and have never used an meggohmeter before. I do not want to spend all day at someone's home troubleshooting their tripping AFCI. So I am looking for an efficient troubleshooting method for tripping AFCI protected circuits.
Thanks,
Jim
AFCI tripping
Thanks for the responses.
A customer's AFCI breaker keeps tripping. After searching on this website I noticed Marc once stating that he uses a meggohmeter to troubleshoot AFCI protected circuits. So I thought I would start a thread dedicated solely with using a meggohmeter to troubleshoot AFCI protected circuits.
I think he uses the meter to look for shorts in between the neutral and ground. If this is so, why not just use a regular ohmmeter? Does a megger's several hundred volts of dc current reveal problems otherwise invisible with an ohmmeter. I built a tesla coil a couple of years ago and somewhat understand insulation breakdown on a 100k volt scale. I have not had any experience with insulation breakdown on a smaller voltage scale before. I have been in the electrical business for 22 years now and have never used an meggohmeter before. I do not want to spend all day at someone's home troubleshooting their tripping AFCI. So I am looking for an efficient troubleshooting method for tripping AFCI protected circuits.
Thanks,
Jim
ceb58
Senior Member
- Location
- Raeford, NC
Some questions. Is this a newly installed circuit? Is it an old circuit that had an afci added? I would first find every thing on this circuit and unplug them. Then try the circuit if it doesn't hold then try ohming out the neutral and ground. If you get a reading then try locating where the ground is touching the neutral. It could be as simple as a ground touching in a recpt. box :smiler as bad as a staple driven to tight some where in the wall. If the circuit holds with nothing plugged in then it's a process of elimination of what device is causing the problem.
r as bad as a staple driven to tight some where in the wall. If the circuit holds with nothing plugged in then it's a process of elimination of what device is causing the problem.
Ravenvalor
Senior Member
- Location
- Piedmont region of NC
JohnJ0906
Senior Member
- Location
- Baltimore, MD
Ooops. :grin: You also need to explain the disadvantages.
Is there something in particular (such as a vacuum) that is causing it to trip?
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
081129-1907 EST
Ravenvalor:
I think the question you want to ask is:
Is the AFCI tripping falsely?
This is hard to determine. You could try switching a vacuum sweep on and off on the AFCIed circuit and see if it causes a trip. Or maybe a large electric hand drill. Or a kitchen mixer. If so find a brand of AFCI that can tolerate the test, and install that and see if the customer has a problem.
AFCIs do two things:
(1) Perform a low grade GFCI function (higher current threshold).
(2) Try to detect abnormal series or shunt arcs.
Ask your self how can you detect an abnormal arc and distinguish this from the normal arc between brushes and the commutator of a universal motor, or switching on and off an inductive load with a mechanical switch. Now you see the problem of making an AFCI device that is free of false alarms.
How can you test an AFCI to determine if it works as you would expect? Not easy.
When the public gets fed up with false trips, then there may be a change of some sort.
If you do not have an independent test to verify the operation of an AFCI, then there is no way to have any confidence in the device. The internal test has nothing that you can correlate with the the true value of the device.
To have an AFCI that has a very high success in detecting arcs that may cause fires may necessitate a high false alarm rate. It may be very hard to detect the difference of a problem arc from a non-problem one. This may not be acceptable to the average customer.
By contrast if for example the US military had been willing to have or respond to a higher false alarm rate the disaster of Pearl Harbor might have been much less. They actually operated in a mode of ignoring useful information from several sources even though it was well known that an attack from Japan was a possibility. In fact some information that came in early Sunday 7 Dec 1941 should have gone imeadiately and directly to the high command. In a sense at least two items of information were quite solid. The radar detection of a large group of airplanes in an unexpected direction and the detecting an sinking of a sub. 7 Dec is again on a Sunday this year.
.
Ravenvalor:
I think the question you want to ask is:
Is the AFCI tripping falsely?
This is hard to determine. You could try switching a vacuum sweep on and off on the AFCIed circuit and see if it causes a trip. Or maybe a large electric hand drill. Or a kitchen mixer. If so find a brand of AFCI that can tolerate the test, and install that and see if the customer has a problem.
AFCIs do two things:
(1) Perform a low grade GFCI function (higher current threshold).
(2) Try to detect abnormal series or shunt arcs.
Ask your self how can you detect an abnormal arc and distinguish this from the normal arc between brushes and the commutator of a universal motor, or switching on and off an inductive load with a mechanical switch. Now you see the problem of making an AFCI device that is free of false alarms.
How can you test an AFCI to determine if it works as you would expect? Not easy.
When the public gets fed up with false trips, then there may be a change of some sort.
If you do not have an independent test to verify the operation of an AFCI, then there is no way to have any confidence in the device. The internal test has nothing that you can correlate with the the true value of the device.
To have an AFCI that has a very high success in detecting arcs that may cause fires may necessitate a high false alarm rate. It may be very hard to detect the difference of a problem arc from a non-problem one. This may not be acceptable to the average customer.
By contrast if for example the US military had been willing to have or respond to a higher false alarm rate the disaster of Pearl Harbor might have been much less. They actually operated in a mode of ignoring useful information from several sources even though it was well known that an attack from Japan was a possibility. In fact some information that came in early Sunday 7 Dec 1941 should have gone imeadiately and directly to the high command. In a sense at least two items of information were quite solid. The radar detection of a large group of airplanes in an unexpected direction and the detecting an sinking of a sub. 7 Dec is again on a Sunday this year.
.
Last edited:
kbsparky
Senior Member
- Location
- Delmarva, USA
Try this first ---
Try this first ---
First thing to do when checking any AFCI circuit is disconnect the load wires from the breaker and see if it still trips.
90% of the time, this has solved the nuisance tripping problems for me. Bad breaker.
If the breaker holds, connect only the neutral conductor back first. 75% of the remaining 10% this will cause it to trip. Usually a pinched wire in a fixture, loose ground wire hitting a neutral terminal in a receptacle outlet, or a crossed neutral in a box with more than one circuit present (all tied together). None of these conditions will trip out a standard breaker.
The most difficult problem to detect is a bad/pinched wire, etc. buried in the walls of the house.
Try this first ---
First thing to do when checking any AFCI circuit is disconnect the load wires from the breaker and see if it still trips.
90% of the time, this has solved the nuisance tripping problems for me. Bad breaker.
If the breaker holds, connect only the neutral conductor back first. 75% of the remaining 10% this will cause it to trip. Usually a pinched wire in a fixture, loose ground wire hitting a neutral terminal in a receptacle outlet, or a crossed neutral in a box with more than one circuit present (all tied together). None of these conditions will trip out a standard breaker.
The most difficult problem to detect is a bad/pinched wire, etc. buried in the walls of the house.
quogueelectric
Senior Member
- Location
- new york
Especially master bedrooms with outdoor access now you are subjecting the afci ckt to an outdoor lighting ckt which I am sure is not moisture friendly but you have no choice because the switch is located in an outlet in the bedroom which has to be afci.
Ravenvalor
Senior Member
- Location
- Piedmont region of NC
Does removing all loads include unscrewing light bulbs and disconnecting fluorescent ballasts? Will not a regular ohmmeter work because it is not powerful enough to travel throughout the circuit and back? How much resistance am I looking for? What if the meggohmeter shows a problem, what is the next step? What if I think the problem is in a computer but the breaker is only tripping occasionally?
Thanks,
Jim
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
081202-0827 EST
Ravenvalor:
An ordinary ohmmeter is only going to have a low voltage source. The Simpson 260 on its high resistance range uses 6 V. On low resistance 1.5 V. Neither of these voltages is going to cause problems with power circuits (things that operate at 120 V). But 6 V might damage something. On the other hand the current from a 260 in the high resistance position under shorted probes is about 50 microamps (120,000 ohms internal resistance), and less current with resistance between the probes. The resulting maximum power dissipation would very low.
My Fluke 27 with a 10 megohm load across the terminals has an open circuit voltage of about 0.75 V in Ohms mode, and in diode mode 2.5 V. With a 1000 ohms shunt load for current measurement and in the ohms mode the current is 115 microamps.
This kind of power and voltage will not stress your circuits.
Megohm meters used for insulation testing are going to apply very much higher test voltages to stress the insulation.
The problem with many loads like TVs, microwave ovens, and other things with electronic components is that many of these have some always on circuits even when the item is powered off. These might be damaged by high voltage.
If you have an ordinary mechanical contact switch that is in good condition and the switch is open, then its only coupling to a load is capacitance until you reach the breakdown of its air gap.
A 120 V magnetic ballast for a fluorescent 8 ft Slimline has a primary DC resistance of about 4.2 ohms. Put a megohmmeter across this primary and it will read a short circuit. Put the meter between the primary or secondary and the case and you will read the respective leakage to case. The test voltage should be in the range of the maximum allowed voltage for the rating of the ballast. I did a quick check for a specified hipot voltage rating for ballasts and did not find one. However, it is not likely to be greatly different than for typical small transformers. Signal Transformer has a rating on at least some of their transformers of "Dielectric Strength - 2500 Vrms Hipot".
Do you need to unscrew an incandescent lamp bulb? If you are testing the wiring directly to the lamp the answer is obviously yes if the test is between the wires. If it is from the wires to ground, then no.
You have to do your own thinking and make a judgement based on what you want to test and how to test it, and the limitations of any connected components.
.
Ravenvalor:
An ordinary ohmmeter is only going to have a low voltage source. The Simpson 260 on its high resistance range uses 6 V. On low resistance 1.5 V. Neither of these voltages is going to cause problems with power circuits (things that operate at 120 V). But 6 V might damage something. On the other hand the current from a 260 in the high resistance position under shorted probes is about 50 microamps (120,000 ohms internal resistance), and less current with resistance between the probes. The resulting maximum power dissipation would very low.
My Fluke 27 with a 10 megohm load across the terminals has an open circuit voltage of about 0.75 V in Ohms mode, and in diode mode 2.5 V. With a 1000 ohms shunt load for current measurement and in the ohms mode the current is 115 microamps.
This kind of power and voltage will not stress your circuits.
Megohm meters used for insulation testing are going to apply very much higher test voltages to stress the insulation.
The problem with many loads like TVs, microwave ovens, and other things with electronic components is that many of these have some always on circuits even when the item is powered off. These might be damaged by high voltage.
If you have an ordinary mechanical contact switch that is in good condition and the switch is open, then its only coupling to a load is capacitance until you reach the breakdown of its air gap.
A 120 V magnetic ballast for a fluorescent 8 ft Slimline has a primary DC resistance of about 4.2 ohms. Put a megohmmeter across this primary and it will read a short circuit. Put the meter between the primary or secondary and the case and you will read the respective leakage to case. The test voltage should be in the range of the maximum allowed voltage for the rating of the ballast. I did a quick check for a specified hipot voltage rating for ballasts and did not find one. However, it is not likely to be greatly different than for typical small transformers. Signal Transformer has a rating on at least some of their transformers of "Dielectric Strength - 2500 Vrms Hipot".
Do you need to unscrew an incandescent lamp bulb? If you are testing the wiring directly to the lamp the answer is obviously yes if the test is between the wires. If it is from the wires to ground, then no.
You have to do your own thinking and make a judgement based on what you want to test and how to test it, and the limitations of any connected components.
.
Ravenvalor
Senior Member
- Location
- Piedmont region of NC
Do electronics have a tendency to leak current to ground? Do they have a tendency to connect the neutral with the ground? If so, should I test them with a regular ohmmeter?
Great posts, I am starting to get the hang of these two issues. One is troubleshooting AFCI circuits and the other is meggohmeters. I am trying to find a good reason to buy a meggohmeter and believe that it will help me tshoot AFCI circuits. With the meggohmeter I start at the panel and work my way through the circuit from there. I cannot test electronic devices for shorts with a meggohmeter but I can hopefully test them with a regular ohmmeter. The meggohmeter is specifically for the house wiring. I need to choose the right setting on the meter for this type of test. Fluke might offer an online course for meggohmeters. The interesting thing about the problem I am having now is the fact that the 3 - circuit breakers trip occasionally. Wednesday night 2 - of them tripped at the same time. They were on different phases though. This house is about 30 years old and maybe the wind is making grounds and neutrals touch. I asked him to lift the ground on his computer system with a groundless receptacle adapter to see if this helps. I appreciate all of the advice recieved on this thread.
Thanks,
Jim
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
081203-1453 EST
Ravenvalor:
Trying to see if you have bad circuit may be the wrong initial direction.
You might start a thread with the following question.
What brands of AFCI, year of manufacture, what part of the country (high altitude vs sea level), have produced the fewest false trips?
Then see how this information correlates with your breakers and location. If something looks better, then install the best one and see if it trips. Only at this point would I start looking for circuit problems.
That two breakers tripped simultaneously sounds like the breakers are sensitive to line transients.
Many on this site think that if the test button on the breaker indicates that the breaker is OK, then the breaker is OK. I disagree. If a breaker produces an excessive number of false trips, then it is not OK independent of what the test button would imply. Further a successful test with the test button does not guarantee that the breaker will successfully detect a dangerous condition. So far no one has provided explicit information on what the test button does on any particular breaker.
.
Ravenvalor:
Trying to see if you have bad circuit may be the wrong initial direction.
You might start a thread with the following question.
What brands of AFCI, year of manufacture, what part of the country (high altitude vs sea level), have produced the fewest false trips?
Then see how this information correlates with your breakers and location. If something looks better, then install the best one and see if it trips. Only at this point would I start looking for circuit problems.
That two breakers tripped simultaneously sounds like the breakers are sensitive to line transients.
Many on this site think that if the test button on the breaker indicates that the breaker is OK, then the breaker is OK. I disagree. If a breaker produces an excessive number of false trips, then it is not OK independent of what the test button would imply. Further a successful test with the test button does not guarantee that the breaker will successfully detect a dangerous condition. So far no one has provided explicit information on what the test button does on any particular breaker.
.
brian john
Senior Member
- Location
- Leesburg, VA
Line and loads isolated ground connected to the ground bus in the panel
Megger the energized conductor to neutral
Megger the energized conductor to ground
Megger the neutral to ground.
1000 VDC test voltage,
Check all loads is the AFCI tripping with loads connected of without loads connected?
Megger the energized conductor to neutral
Megger the energized conductor to ground
Megger the neutral to ground.
1000 VDC test voltage,
Check all loads is the AFCI tripping with loads connected of without loads connected?
electricmanscott
Senior Member
- Location
- Boston, MA
You are spinning what has been said on this site. If my memory is correct many believe the only "official" (lack of better word) way to test the afci is with the test button. That of course does not mean the breaker is "ok" per se. But it is the only way to check them. Or is it?
I have ZERO confidence that AFCI's are worthy of their price, mandatory installation, and headaches.
electricmanscott
Senior Member
- Location
- Boston, MA
bjp_ne_elec
Senior Member
- Location
- Southern NH
Year/Month/Day Time based on 24 hour (14:53 = 2:53 PM) Eastern Standard Time
2008/Dec/03
- Status