GFCI trouble when using a portable generator

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11bgrunt

11bgrunt

Pragmatist
Location
TEXAS
Occupation
Electric Utility Reliability Coordinator
A concrete contractor uses Hilti core drills served by portable generators for remote locations having no 120VAC. The core drills have GFCI protection in the cords. The drills will work every day until they don't. Test the drill on utility power and the drills work fine. Each time this has happened, a new generator was purchased to run the core drills, and then everything works.
What is happening to these 3KW generators that will not let the GFCI reset? The gensets are locally purchased at a big box store.
I expect load to trip GFCIs, not the source power.
 
It's usually due to an intact neutral/ground bond, but that's not something that normally changes over time.

The bond much is more likely to accidentally break than accidentally be made.
 
Some are branded different but expect the same company in China is the manufacture.
 
If you loose the source side neutral, a cord end GFCI will usually be able to be reset.
Could something be shaking loose in the generators?
 
I’ve read the original post multiple times and I can’t tell for certain which GFCI is tripping. The one on the generator or the one on the tool cord?
 
The gfci is in the drill cord. The cord is usually connected to the genset using the 30A RV receptacle with an adapter.
This has happened so many times that leakage from high humidity is probably not the cause. When the genset stops working with the drills, it never starts working with the drills again.
 
If the drills are 120V, why are they using the 30A receptacle and not the 120V receptacle? Most small gennys have both a 30A, 240V and a 20A, 120V receptacle.
I would say something in the adapters is causing the GFCI not to reset. Also, the 120V receptacle on a genny is a GFCI, maybe they could do away with the GFCI on the cord and just use the GFCI on the genny.
 
Is you genset one with th;e capacitor used fo exitation? High frequency harmonics are what trips the GCI in the cord.

Had similar happen, solution was to add an inductor in the chassis connection EGC>
 
I had failures of cord set GFCIS with Hilti core drills. It may be the core drill high amps is causing the GFCI to fail on the generator.
 
Worked on a lot of sign-posting trucks for a government agency ... and there was a trend of generators suddenly not working. Found out that if a portable tool was working when the generator suddenly stopped working ... the generators permeant field would collapse.

The solution we found was to insert a 100-watt light bulb in series to an extension cord and plug it in to the generators 120 outlet. This procedure would reestablish the generators field.

Don't know if this means anything to the posted problem. Also, these generators were not equipped with GFCI.
 
Given what we know, instead of buying one cheap generator after another, I’d probably buy a Bosch hammer drill instead.
If nothing else, it would provide another data point to aid in troubleshooting.
In fact, just rent one (of any different brand) and see if it works on any of the existing generators.
 
ptonsparky said:
Can the scrapped generators provide power to any other piece of equipment or are they dead in the water?
Click to expand...
Other tools work on the gensets.
The cordset trips and always resets when connected to utility power or a new genset.
The core drills can cut many large holes. A core drill is the only tool that will do the job.
 
Little Bill said:
If the drills are 120V, why are they using the 30A receptacle and not the 120V receptacle? Most small gennys have both a 30A, 240V and a 20A, 120V receptacle.
I would say something in the adapters is causing the GFCI not to reset. Also, the 120V receptacle on a genny is a GFCI, maybe they could do away with the GFCI on the cord and just use the GFCI on the genny.
Click to expand...
The genset gfci is 15A and a good load will trip out on overcurrent. They run a vacuum simultaneously and the vacuum is in the genset gfci.
The Hiltis have the same issue in the 30 and the gfci.
 
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