Fluke Multimeter continuity pulsating

[Mustwin351]

Today I was searching for the cause of a breaker tripping. Unrelated to the breaker tripping but on the same circuit are four 70w pulse start metal halide fixtures. When testing continuity from hot to ground my meter would give me a pulsating continuity beep as seen in the video. I still got the same result on one of the fixtures when I tested it’s black lead to ground so it was isolated from the rest of the circuit. The neutral of the fixtuee was still conected to my grounded conductor when I did this but don’t believe that should affect it. What may be the cause for two different fluke meters to act like this?

 

[WarrMann]

Seems like you're trying to look for continuity through the ballast with a lamp in the fixture? What are you trying to determine by doing this? You've got a transformer, capacitor, and a bulb to get on the way of continuity.

Do you get any continuity from the ballast input (power in) wires to ground without the neutral involved? Cause that's an issue.

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[Mustwin351]

Seems like you're trying to look for continuity through the ballast with a lamp in the fixture? What are you trying to determine by doing this? You've got a transformer, capacitor, and a bulb to get on the way of continuity.

Do you get any continuity from the ballast input (power in) wires to ground without the neutral involved? Cause that's an issue.

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You are correct. I was looking for the cause of the breaker tripping which I found. I considered that I may be reading through the ballast but it seemed strange that the meter would behave the way it did. I figured reading through a coil (ballast) I would get solid continuity.

 

[WarrMann]

My money is on the capacitor making your fancy fluke act up. What was tripping the breaker in the end?

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[Mustwin351]

My money is on the capacitor making your fancy fluke act up. What was tripping the breaker in the end?

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Ended up being a short or ground fault in an emergency lighting inverter/backup battery unit. I should have taken a picture I’ve never seen a a setup quite like it. There were 4 units each with 2 good size lead acid batteries each. I couldn’t get to two units and somebody had disconnected wires in them before me and had them capped so they were not even being used. I just isolated the 4 units on the circuit and called it a day. Thr breaker held for half an hour after that instead of tripping in a couple of seconds.

 

[GoldDigger]

If the backup unit was putting voltage onto the wires it could easily cause the meter's continuity function to misbehave.

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[Mustwin351]

If the backup unit was putting voltage onto the wires it could easily cause the meter's continuity function to misbehave.

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My meter was pulsing after I isolated the battery units.

 

[ptonsparky]

I watched it again this morning. No sound.

Oh, No hearing aids in.

Did you happen to take a voltage reading as it sat? Sounds like you were testing a charged capacitor and the Fluke was saying No...No...No.

My Flukes aren’t as new as yours and it’s been awhile since I checked continuity on a circuit that had voltage present.

 

[Mustwin351]

I watched it again this morning. No sound.

Oh, No hearing aids in.

Did you happen to take a voltage reading as it sat? Sounds like you were testing a charged capacitor and the Fluke was saying No...No...No.

My Flukes aren’t as new as yours and it’s been awhile since I checked continuity on a circuit that had voltage present.

Yes sir. No voltage present when I checked.

 

[Mustwin351]

I’m thinking it has something to do with the capacitor like warrman said. Maybe the dc voltage my meter puts out for continuity starts to reads the circuit as open because the capacitor starts to charge and then it starts to discharge and my meter reads continutiy? They cycle repeats itself over and over. Next time I come across a cap I will check.

 

[ptonsparky]

I’m thinking it has something to do with the capacitor like warrman said. Maybe the dc voltage my meter puts out for continuity starts to reads the circuit as open because the capacitor starts to charge and then it starts to discharge and my meter reads continutiy? They cycle repeats itself over and over. Next time I come across a cap I will check.

Something would need to be there to make it discharge at a certain voltage and in your case, suddenly. May very well be integrated into the pulse start circuit.

Your meter would typically charge the capacitor on ohms or continuity setting. It would gradually increase in value and decrease in sound as it charges.

Did you check for the presence of DC voltage? That is what would be on a charged capacitor.

 

[kwired]

Something would need to be there to make it discharge at a certain voltage and in your case, suddenly. May very well be integrated into the pulse start circuit.

Your meter would typically charge the capacitor on ohms or continuity setting. It would gradually increase in value and decrease in sound as it charges.

Did you check for the presence of DC voltage? That is what would be on a charged capacitor.

Was my thought right away, something to do with pulse start circuit.

 

[Mustwin351]

Something would need to be there to make it discharge at a certain voltage and in your case, suddenly. May very well be integrated into the pulse start circuit.

Your meter would typically charge the capacitor on ohms or continuity setting. It would gradually increase in value and decrease in sound as it charges.

Did you check for the presence of DC voltage? That is what would be on a charged capacitor.

No I did not. The capacitor should have been discharged the breaker has been tripped for months. I was just now able to get to work on it.

 

[kwired]

No I did not. The capacitor should have been discharged the breaker has been tripped for months. I was just now able to get to work on it.

Missing or not working discharge resistor and that capacitor could hold a charge for a long time.

Pulsing could be coming from the pulse start circuit also, I don't know enough details of exactly how they work, but I believe is common to have a capacitor charging circuit of some sort in them.

If you are testing for ground fault and still have one input lead connected to the neutral, you get continuity back to the main bonding jumper and get a false positive ground fault test result.