This week we have had 2 seperate duplexes where the 200 Amp main breakers have tripped randomly and no breakers at the panel were tripped. the first one we went to, we took loose the feeder wire to the interior panel and tested continuity to be sure that there were no problems between the Meter pack and the interior panel. We then relanded the feeder wires and turned on the breaker with ALL interior breakers off and it held fine. Then we slowly turned back on all the interior breakers and all held until we turned on an AFCI breaker and then some lights flickered but nothing tripped. we turned it off and back on, everything seemed fine for few days and then the main at the meter tripped. We just received a call tonight that another duplex tripped the main at the meter and nothing inside tripped, the HO waited a while and then turned the main back on and it held. We did not wire these duplexes and they are about a year old and we have no idea what's going on and any ideas would be helpful. i will try and respond to any questions ASAP. thanks, justin.
Multiple Duplex main tripping???
- Thread starter justin
- Start date
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brantmacga
Señor Member
- Location
- Georgia
- Occupation
- Former Child
i once made contact, inadvertently, between a neutral and hot of a 3 wire 30a circuit. it didn't trip the 30a cb, but tripped the main. maybe you've got a leak past the loadcenter.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
No questions. Try a clamp-on ammeter and see if the breaker is really being subject to anywhere near 200a, while trying to duplicate the conditions, such as appliances, HVAC, etc.
brian john
Senior Member
- Location
- Kilmarnock, Va
- Occupation
- Retired after 52 years in the trade.
1. As Larry said measure current.
2. Perform a FOP test (Fall of potential) test across the Main CB with load on (as much load as possible). FOP test is a measurement of voltage drop across the poles of the CB, L1 line to L1 load, L2 line to L2 load, readings should be in the millivolt range. Feel the CB for heat or use a not contact thermometer
3. If leakage current is the issue or an intermittent short a continuity tester is not the device of choice, you should use a meggger. ALL LOADS MUST BE OFF.
4. Swap the CB out, Based upon the size of this circuit breaker high current testing is not warranted.
2. Perform a FOP test (Fall of potential) test across the Main CB with load on (as much load as possible). FOP test is a measurement of voltage drop across the poles of the CB, L1 line to L1 load, L2 line to L2 load, readings should be in the millivolt range. Feel the CB for heat or use a not contact thermometer
3. If leakage current is the issue or an intermittent short a continuity tester is not the device of choice, you should use a meggger. ALL LOADS MUST BE OFF.
4. Swap the CB out, Based upon the size of this circuit breaker high current testing is not warranted.
kbsparky
Senior Member
- Location
- Delmarva, USA
If they are experiencing the same problems in multiple nearby units, they may have had a recent catastrophic event, such as a direct lightning strike or large power surge at or near the meter stack. 
Had any bad storms out there just before all this started? Or maybe the POCO dropped a high voltage wire across a transformer briefly (although they might not want to readily admit such a thing)
IF this is the case, those breakers are probably fried, and will need to be replaced.
Had any bad storms out there just before all this started? Or maybe the POCO dropped a high voltage wire across a transformer briefly (although they might not want to readily admit such a thing)
IF this is the case, those breakers are probably fried, and will need to be replaced.
My guess would be a condensing(s) unit going bad. They have large enough breakers to let the main trip either first or at the same time.
It's also just about that time of the year that everyone is firing up the AC. What area are you in?
Steve
It's also just about that time of the year that everyone is firing up the AC. What area are you in?
Steve
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Any chance of there being a bit of malicious mischief going on? Are the breakers that tripped located in an area that anyone can get to?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
A-ha! Conspiracy theory!charlie b said:
Awg-Dawg
Senior Member
- Location
- Dayton Ohio
LarryFine said:
LOL!
brian john
Senior Member
- Location
- Kilmarnock, Va
- Occupation
- Retired after 52 years in the trade.
Don't laugh... I did a investigation of tripping CB's (actually turned out to be openings)the customer spent quite a bit of money, IR, CB testing, cable testing, power monitoring. This never happened when I was on site and they would not wait for me to get there to restore power.
I finally suggested a hidden camera, the customer balked but finally gave in. The assistant manager was turning them off, at times coming in the back door turning them off and leaving unseen.
I finally suggested a hidden camera, the customer balked but finally gave in. The assistant manager was turning them off, at times coming in the back door turning them off and leaving unseen.
kbsparky
Senior Member
- Location
- Delmarva, USA
Ah-HA!! Conspirousy confirmed!!brian john said:
So what was his motive for doing such a deed? Disgruntled? Or was an accomplice on the receiving end of some of the expenditures trying to "fix" the problem??
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Isn't that a pig that's had a laryngectomy?kbsparky said:
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