GFCI Tripping During Storms

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davidgarrett

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Greenville, SC
I have a customer who has a GFCI receptacle in a basement that trips any time there is a storm in the area. (late afternoon thunder and lighting storms are common around here) I have not been to the residence yet as it is about an hour drive and in the middle of no where so I'm hoping to go as prepared as possible. Does anyone think it's simply a bad GFCI or could it be a grounding problem with the house? As far as I know, this is the only GFCI that trips in this manner. The house is only about five years old so it should have proper grounding... of course that's an assumption at this point.
 
Remember that a GFCI has a 5ma sensitivity and you may have just the right circumstances to trip the GFCI during a lightning storm.
I built a home one the required a 515' well where the pump control was next to my work bench in the basement.
While standing at my work bench during a lightning storm quite often I hear a small snap coming from the controller enclosure just prior to hearing a crack of thunder in the distance. As a rule of thumb I was to understand that after seeing a flash of lightning you able to count one second for each mile before you hear the thunder. After hearing the snap due to an lighting arrestor of some sort I was able to count a number of second as I anticipated the sound of thunder.
As such I wouldn't be of any surprise to me that there is a rare circumstance that affects the GFCI which causes a trip during a lightning storm. I have the same thing happen to a GFCI after a sever lightning but it was a very rare occurrence. It may have only happen once or twice in 20 years.
 
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davidgarrett said:
I have a customer who has a GFCI receptacle in a basement that trips any time there is a storm in the area. (late afternoon thunder and lighting storms are common around here) I have not been to the residence yet as it is about an hour drive and in the middle of no where so I'm hoping to go as prepared as possible. Does anyone think it's simply a bad GFCI or could it be a grounding problem with the house? As far as I know, this is the only GFCI that trips in this manner. The house is only about five years old so it should have proper grounding... of course that's an assumption at this point.
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Is anything plugged into the GFCI receptacle or downstream protected receptacle at the time? If any equipment has a surge suppressor connected to ground, then a lightning induced surge will trip the GFCI.
 
I would not say this is uncommon. It could be EMF's from the lightning causing it to trip. It has been discussed on the forum before and I have caused a GFCI receptacle to trip by keying a 800 Mh radio near the receptacle. The EMF's may be interfering with the electronics of the receptacle. You may want to try replacing the GFCI receptacle. with a GFCI breaker on the circuit.
 
templdl said:
Remember that a GFCI has a 5ma sensitivity and you may have just the right circumstances to trip the GFCI during a lightning storm.
I built a home one the required a 515' well where the pump control was next to my work bench in the basement.
While standing at my work bench during a lightning storm quite often I hear a small snap coming from the controller enclosure just prior to hearing a crack of thunder in the distance. As a rule of thumb I was to understand that after seeing a flash of lightning you able to count one second for each mile before you hear the thunder. After hearing the snap due to an lighting arrestor of some sort I was able to count a number of second as I anticipated the sound of thunder.
As such I wouldn't be of any surprise to me that there is a rare circumstance that affects the GFCI which causes a trip during a lightning storm. I have the same thing happen to a GFCI after a sever lightning but it was a very rare occurrence. It may have only happen once or twice in 20 years.
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Just an FYI-Rule of thumb is-It's 5 seconds per mile, approximately, as the speed of sound is around 1100 feet per second, approximately, depending on temp, barometric press and humidity
 
I would be sure to replace the existing receptacle with a good quality one. Some of the cheap Chinese junk out there causes a lot of problems.
 
templdl said:
Remember that a GFCI has a 5ma sensitivity and you may have just the right circumstances to trip the GFCI during a lightning storm.
I built a home one the required a 515' well where the pump control was next to my work bench in the basement.
While standing at my work bench during a lightning storm quite often I hear a small snap coming from the controller enclosure just prior to hearing a crack of thunder in the distance. As a rule of thumb I was to understand that after seeing a flash of lightning you able to count one second for each mile before you hear the thunder. After hearing the snap due to an lighting arrestor of some sort I was able to count a number of second as I anticipated the sound of thunder.
As such I wouldn't be of any surprise to me that there is a rare circumstance that affects the GFCI which causes a trip during a lightning storm. I have the same thing happen to a GFCI after a sever lightning but it was a very rare occurrence. It may have only happen once or twice in 20 years.
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I just received some material from Mike Holt yesterday and there was a chart with formulas included which shows to divide the seconds by 4.68.
 
wirebender said:
I just received some material from Mike Holt yesterday and there was a chart with formulas included which shows to divide the seconds by 4.68.
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Close enough to 5 seconds per mile as RichB says.
 
James S. said:
Am I the only one that thinks there is an outlet outside that is getting wet?
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I have an outlet under the eaves on my deck that's in a splash zone when my gutters are clogged. When my GFCI trips during a rainstorm that's how I know it's time to clean my gutters.
 
RichB said:
Just an FYI-Rule of thumb is-It's 5 seconds per mile, approximately, as the speed of sound is around 1100 feet per second, approximately, depending on temp, barometric press and humidity
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Thanks. I miss spoke and stand to be corrected Being off a factor of 5. I should have noted the temperature, barometric pressure, and humidity which I wasn't thinking of at the time of some 30+ years ago.
But my point was the to,e that I heard the snape until the time that I heard the thunder some seconds later which was "some" distance away.
 
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