We have an lab installation where we installed GFCI breakers to serve the receptacles along the countertops in the labs. Upon move-in, the Owner has experienced instantly tripping of the GFCI breaker when they start a device (ex. centrifuge). To troubleshoot, we verified the contractor had connected the neutrals correctly, both in the panel and at the receptacles. There are multiple (up to three single phase circuits) in a single conduit, but all have independent neutrals. The equipment did the same thing on any circuit we checked. We then tested the same piece of equipment on a GFCI receptacle and the equipment functioned properly. The breakers are Square D QOBs and we did verify the devices are correctly connected and also do not violate any of the installation instructions that could cause nuisance tripping (ex. <250 feet of load conductor, etc.). All lab spaces have individual panelboards, so distance should not be an issue. Has anyone experienced a similar incident or have suggestions?
Lab GFCI Breaker Nuisance Tripping...
- Thread starter asigmon
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tonyi
Senior Member
Re: Lab GFCI Breaker Nuisance Tripping...
Will an ordinary resistive load, like a 40W bulb in a grounded lamp, cause a trip?
Damaged netrals in the pipe could cause what you're seeing, but unless the original installation was real bad, its hard to imagine they'd all be whacked. You could disconnect some of the branch neutral's and see if there's any continuity with gnd/pipe to verify this.
Will an ordinary resistive load, like a 40W bulb in a grounded lamp, cause a trip?
Damaged netrals in the pipe could cause what you're seeing, but unless the original installation was real bad, its hard to imagine they'd all be whacked. You could disconnect some of the branch neutral's and see if there's any continuity with gnd/pipe to verify this.
short circuit faulted
Member
- Location
- Columbia SC
Re: Lab GFCI Breaker Nuisance Tripping...
Are the circuit breakers rated for equipment of for personnel protection? Breakers rated for equipment have high trip threshold than personnel, Check with your SQD Rep. they should be able to help with the problem, as it is in their best interest to have satisfied, repeat customers.
Are the circuit breakers rated for equipment of for personnel protection? Breakers rated for equipment have high trip threshold than personnel, Check with your SQD Rep. they should be able to help with the problem, as it is in their best interest to have satisfied, repeat customers.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Lab GFCI Breaker Nuisance Tripping...
Most likely its not a bad breaker but rather a problem with the load. To be sure install a GFCI receptacle at the load location, and try turning on the load.
Most likely its not a bad breaker but rather a problem with the load. To be sure install a GFCI receptacle at the load location, and try turning on the load.
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