Earth leakage trip with lightning

Tony52October 30, 2011

I recently replaced the earth leakage due to regular trips and it had been in place for over 10 years. The new earth leakage unit now trips every time there is lightning in the area. Neighbours do not have the same problem. There is a surge protector ahead of the earth leakage unit. Any suggestions?

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You are not likely to find very much information or help here.

The board s mostly fr North American electrical wiring under the US National Electrical Code or Canadian codes.

    Bookmark   October 30, 2011 at 9:25AM
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The earth leakage trips are reporting an electrical fault. Your existing defect is insufficient to trip. But with added noise from nearby events (ie lightning), then that leakage current increases to cause trips. Stop blaming the messenger. Somewhere down cable is a fault. A milliamp leakage that must be corrected.

For example, a rodent had eaten into a buried wire. That exposed wire caused a trip every time the ground was wet with rain or a hose. Using a hose, we found the wiring defect. Solution was to wrap the rodent's hole with electrical tape. No more trips.

You must do same to find your obviously existing defect. Fix the leakage. In your case, lightning causes just enough increased current to cause a trip. Stop replacing what is properly reporting a defect - a constant milliamp electrical leakage to earth that remains too low (most of the time) to cause a trip.

    Bookmark   November 1, 2011 at 1:02PM
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Lightning itself creates displacement currents in the earth that can trip leakage detectors.

An actual stroke to earth also produces significant RF energy that can couple (both electric field and magnetic field) into the sensitive electronics needed to detect leakage.

    Bookmark   November 1, 2011 at 1:34PM
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Lightning creates displacement currents in earth that do not pass through that leakage detector. Otherwise all leakage detectors are tripping with every nearby lightning strike. Obviously, that does not happen because these assumed lightning currents are not, in reality, passing through and tripping all leakage detectors.

Currents created by those electric and magnetic fields are so close to zero as to be made irrelevant by an NE-2 neon bulb (a bulb found inside glowing 'night light' switches). Of course, useful posts also explain that with numbers.

An antenna is designed to maximize currents created by electro-magnetic fields (ie lightning). So a nearby lightning strike may create thousands of volts on that antenna lead. We connect that current to a neon glow lamp. That less than 1 milliamp current, conducted by a neon glow lamp, means thousands of volts are reduced to near zero. Why? Because electric currents created by nearby lightning is near zero. Is hyped in subjective claims that never include numbers.

Lightning is a near zero current through that one leakage detector. That near zero current is just enough to trip that one detector due to a much larger current leaking constantly and elsewhere.

Again, any recommendation that forgets numbers is often a myth provided by parables and wild speculation. To know something always means numbers and other hard facts.

One leakage current detector is tripping probably due to an existing leakage current. A tiny current added by a nearby lighting strike is simply enough to trip that one detector - and not other detectors.

    Bookmark   November 1, 2011 at 7:00PM
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"Lightning creates displacement currents in earth that do not pass through that leakage detector. "


The capacitance of the wiring takes current to charge.
It passes through the system on grounded and grounding conductors and can easily upset a ground current circuit since it is often not present on a the hot conductor, or is delayed in time from transformers and other sources of delay.

"Currents created by those electric and magnetic fields are so close to zero as to be made irrelevant by an NE-2 neon bulb"


We use spark gaps to clamp voltage and provide a discharge path for a reason.

Neon bulbs are not used since their break over voltage is actually not that well controlled.

It is about 90 V, but varies since it is not an important parameter for the bulbs.
Their power dissipation is also very limited.

    Bookmark   November 1, 2011 at 9:31PM
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Neon bulbs immediately become near zero volts when triggered. Power dissipation is very limited. And that tiny current trough a neon bulb is more than sufficient to make currents from nearby electromagnetic fields completely irrelevant. Nearby lightning creates current that trivial. A less than 1 milliamp conducted by a neon bulb is the entire current from nearby lightning. Well below what is necessary to trip a leakage detector.

Lightning is insufficient to trip a leakage detector. But may be enough to trip that leakage detector IF another current leak also exists.

It is tripping probably because another larger leak also exists. That other leak, alone, is not quite large enough to trip the detector. Fix the problem. That other leakage.

BS is only found in a post that also uses the expletive. That discusses things irrelevant to this topic and the OP's problem. Lightning does not explain a tripped leakage detector. Another current leak somewhere in that circuit does.

    Bookmark   November 3, 2011 at 1:54PM
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"Neon bulbs immediately become near zero volts when triggered. Power dissipation is very limited. "

Except that they quickly explode if the current is not limited or is large from heating of the gas.

You keep posing things about lightning and surges that are in opposition to everything we have been doing for many many years for lightning protection.

The turn on for a neon bulb is around 90 V, and that is more than enough to destroy electronics.

All the types of leakage detectors can be tripped by lightning currents flowing on the leads they are sensing, or coupling into the amplifiers and comparator circuits used to trip the device.

Almost any type of arc will produce enough EMI noise to trip current sensing devices if the it is in close physical proximity.

We had a Jacob's ladder powered by an oil burner high voltage transformer that would trip every GFCI device within about 20 feet, and tripped the 3-phase leakage system we use for testing other equipment.

It was initially not in use, but when we started testing a 3-phase power supply and left the Jacob's ladder turned on it sensed leakage and turned off our 3-phase very reliably.

    Bookmark   November 3, 2011 at 3:08PM
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"Leakage detector" (or any AFCI, GFCI, fancy electronic circuit breaker, etc):
Fault Sense circuitry -> Amplifier -> Release Solenoid/Motor

When a near-enough lightning strike occurs, you hear a crackle from the speakers of a lot of audio equipment, especially cheaper, less-well-shielded stuff. Why?

You've got a ton of RFI/EMI. Amplifiers pick it up. An AM radio is nothing more than a high-gain amplifier with a bandpass filter and a rectifier in front of it. Remove the filter and the rectifier. The lightning's electrical crap is picked up VERY WELL by the remaining amplifier, and sent to the speaker, which turns it into a noise you can hear.

So what if you've got this "leakage current detector" instead? It's just an amplifier, hooked up to some circuitry designed to sense "leakage current"... When ITS amplifier picks up that same interference, what is it going to do with it?

Answer: send it on to the solenoid or motor to trip the mechanical disconnect, shutting off your power.

My answer to the original question: your new LCD is designed with a higher-gain amplifier than the old one, and is thus picking up enough interference to trip... *OR* the new one is poorly-shielded/grounded (is it by any chance in a plastic case, and the old one metal?)

All of the anecdotal stories in here say roughly the same thing, but I think I've got you all beat: I can trip the GFCI in my kitchen by standing next to it and sending a text message from my cellphone.

    Bookmark   November 7, 2011 at 8:10AM
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> but I think I've got you all beat: I can trip the GFCI
> in my kitchen by standing next to it and sending a text
> message from my cellphone.

Which is also how I get free gasoline from gas pumps. Sometimes the pump charges me negative. Free money. Inference is that profitable on properly designed equipment.

    Bookmark   November 11, 2011 at 11:31PM
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"I can trip the GFCI in my kitchen by standing next to it and sending a text message from my cellphone."

Electro Magnetic Interference (EMI) is (and has been) an insidious problem for 20-30 years now.

The FCC standards cover inadverte3nt emissions, and set the power limits for desired emissions (like the actual RF a cell phone uses to communicate with the nearest tower).

Typically electronic equipment is required to at least tolerate the allowed leakage (inadvertent emissions) and desired emissions.

The issue is very much a range problem.
Get a cell phone close enough and the emissions may not have dropped to the limit.
The FCC recognizes this and even has language of 'relocating to avoid interference.'

The pickup coil used to monitor the net current in the conductors of a GFCI type device is very sensitive to ANY magnetic field couples to the coil.
Align it correctly and then fail to bad limit the signal to around 60 Hz and the they are vulnerable. The fast reaction reacquired (ad needed for safety) of the devices puts hard limits on the bandwidth reduction that can be used.
the period of 60 Hz is around 16.7 milliseconds.

We want a GFCI to trip much faster than that, but this means it must have a larger bandwidth for the sensor and circuitry.
this makes it more vulnerable to electrical noise being coupled and triggering the device.

The electrical 'noise' produced by lightning or any arc) has a very large bandwidth, and (for lightning) a very high amplitude depending on proximity to the strike.

There is very little that can actually be done without significant expense to protected electronics from anything physically close. Grounded sheet metal enclosures (when was the last time you saw one?) are a first line of defense.

It may be time to further tighten the FCC standards since they have been static for a while now, and many new sources have been introduced.
Older electronics may never have been tested against the new sources adequately.

This is one of the reasons for cell phone restrictions in many hospitals.
They have older equipment still in use, and do not want to take ANY chance of interference from newer sources.

    Bookmark   November 13, 2011 at 10:26AM
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