# GFCI does not save mouse



## TopamaxSurvivor (May 2, 2008)

I recently installed a quad outlet on the end of a counter. The general contractor removed the cover for painting. Over night a mouse tried to climb into the box between the outlets. The GFCI protection tested good, but it wasn't good enough to save the mouse. He got the electrical chair for merely trespassing!


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## patron (Apr 2, 2009)

must have hit the 'line' wires
which are always hot

not the 'load' wires
which use the GFCI
and trip it

am i right ?


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## Karson (May 9, 2006)

I was working in a computer room one Sat and a electrition was working on the electric panel.

All of a sudden a bright flash came from behind the computers. The electrition came out with sparks burned into his safety glasses. He didn't look too happy. He had run a screwdriver across a 660 Volt line.

All of the computers came grinding to a halt.


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## mojapitt (Dec 31, 2011)

About 3 years ago a squirrel committed suicide taking out the power across about half the city I work in.


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## crank49 (Apr 7, 2010)

A cat got into one of our arc furnace transformer rooms a few years back.
13,200 volt 15,000 KVA transformer. 
Cat must have chased a mouse up the buss tower and got on the incoming line.
Created a new definition for cat litter.
About the only thing still intact was a piece of tail.
Knocked out the mains for about half of the town.


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## TopamaxSurvivor (May 2, 2008)

David, Click the link and it will show you a picture of the quad outlets. They are down stream from the GFCI. Hot on the right and neutral on the left. Obviously, a mouse does not require 5 milli-amps for electrocution. GFCIs are a wonderful safety invention, but not sure I would want to bet my life of one!

Karson, The voltages over 250 have a potential of ionizing the atmosphere. He and maybe even you were luck that day.

Monte, Lots of animals and birds get into IT! In the Birds of Prey Refuge along the Snake River, moving the lines to a width wider than an eagle's wing span has been a big help to them ;-)

Crank, that is definitely a new definition of cat litter ;-)


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## longgone (May 5, 2009)

Should have been a wireless mouse…


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## oldnovice (Mar 7, 2009)

*TopamaxSurvivor* GFCI is to electricity as Sawstop is to woodworking … they are both good technologies but I don't want to test them with my body!


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## TopamaxSurvivor (May 2, 2008)

Me either. Obviously Sawstop works better on wieners than GFCIs work on mice ;-))


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## bluekingfisher (Mar 30, 2010)

I hope you're ensured Bob, the Federation of Mice and all things wild will have you for not installing the appropriate "Mice keep out" signage.

Roll on retirement!


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## stefang (Apr 9, 2009)

The mice here like to chew on wires under cars. they've caused a lot of fires. My son's car burned up that way quite a few years ago.


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## EEngineer (Jul 4, 2008)

You have to understand how GFI works.

The GFI compares current flowing out through the HOT line (black) and compares it to current returning on the neutral line (WHITE). If there is a difference greater than ~5-10 mA, then it will trip. The assumption is that somebody or something is conducting current through a separate path to ground.

The mouse probably got across the line and neutral connections, which the GFI allows, and electrocuted himself.

GFI is not universal protection! If you plug a cord into a GFI circuit, grab the HOT in one hand and NEUTRAL in the other (providing a direct path through your heart) then you WILL electrocute yourself and the GFI will never trip.

If, however, you grab the HOT line in one hand and touch a ground rod with the other hand, the GFI will trip and save your life.


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## Tedstor (Mar 12, 2011)

given your handle- I'll assume you're correct. That said, thanks. The best, simplest explanation I've read of GFI.


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## GeneR (Feb 3, 2013)

I am not sticking my weiner on a sawstop or gfci.  And you are correct the gfci 9nly works on things plugg3d into it.


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## Grandpa (Jan 28, 2011)

The GFI is like the safety on a firearm. The ranger tells us they are a mechanical device that sometimes works and should be treated as such.


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## TopamaxSurvivor (May 2, 2008)

Good point EE. I did not think of the mouse being in the normal circuit.


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## 111 (Sep 2, 2013)

Was pulling out a fuse (using channel locks) from a 3 phase disconnect that was wired directly to the incoming hots, (no breaker) when I touched the sides with the pliers. Saw the biggest white flash and was knocked on my but, wasn't shocked, just jump started.


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## EEngineer (Jul 4, 2008)

And you are correct the gfci 9nly works on things plugg3d into it. null statement

The GFI is like the safety on a firearm. very poor analogy. In fact, it is nothing like a safety on a firearm!

I did not think of the mouse being in the normal circuit.

Well, that shocks me, Topamax. You yourself said he crawled up in between the sockets. That is just exactly where the HOT and NEUTRAL have exposed terminals right next to each other.

Look, there absolutely is no substitute for understanding exactly how these protection mechanisms work!


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## TopamaxSurvivor (May 2, 2008)

*Well, that shocks me, Topamax.* Shocks me too EE ;-) Must be time to retire. I thought I had pretty well recovered from Topamax Poisoning, but once in a while I will have a total collapse of rational thought processing when something so simple pops up! I have known how it works for as long as I can remember. It is surprising how many "electricians" do not have a clue!


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## Grandpa (Jan 28, 2011)

The GFI is like the safety on a firearm. very poor analogy. In fact, it is nothing like a safety on a firearm!

The point I was trying to make was don't trust your life on anything. If it saves you life good but don't depend on anything. Be careful. I wouldn't put my finger in a SawStop either. If it saves a finger great.


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## Dark_Lightning (Nov 20, 2009)

Grandpa, when I train people to shoot, I point out that the safety is a mechanical device like any other, and is prone to failure like any other. As you said, "don't trust your life on anything." On this I will never disagree.


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## Loco (Aug 11, 2013)

A good ZZZAP ! now and then stimulates the soul.


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## Karson (May 9, 2006)

Loco:

You are so right. I had a couple of horses a few years ago and I kept them in by the use of an electric fence. Every so often grass would grow up and short out the fence and I'd find my horses wandering around the neighborhood.

This one time I put them back in the yard and cleaned up all the grass and waited. This one horse walked up to the fence and stuck it's nose on the electric wire to see if it was hot. All of a sudden it was running all around the yard. A good zap helped her that time.


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## MT_Stringer (Jul 21, 2009)

Years ago, a "Throwdown Rat" caused a power outage on our ethylene unit which resulted in an emergency shutdown. That bit of chaos upset our unit (Utilities) which eventually led to most of our equipment shutting down for various reasons. It was a bad day (or week) indeed. Just so happens, as my luck would have it, I was right in the middle of it. :-(

That is what "they" determined was the root cause - a rat!


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