A/C Outlet Underwater

[wyliesdiesels]

I can see the argument for the gfci not tripping from a 2 wire feed but with a ground wire it should. I would run it from another recept box to that outlet. This would kill the wires not leave them live. I dropped a drill in water fed gfci, did trip it.
It was so long ago can't remember if it was 2 or 3 wire drill.

A GFCI DOESNT need a grounding conductor to function/trip upon ground fault.

 

[sberry]

I realize this but a circuit with one and in water would certainly have another pathway for ungrounded current. Either way most of this is moot if it is not protected on the front end in this case, power is still live. When it wasnt flooded it worked right with stuff plugged in. At 5ma toss a tool in the water even 2 wire sposed to trip it but seems a grounded 3 wire might be even faster, maybe doesn't make any difference either. It was just a thought.

 

[sberry]

I may have misunderstood one of the earlier posts but if a gfci trips on land only makes sense it would trip if something connected to it went in the water, what would be a bigger fault other than something connected by a ground wire? It works if it's fed 2 wire and it works for 2 wire equipment,,, which it the basic point, for use with ungrounded equipment but if it has 3 in and 3 out it is a direct pathway other than neutral. Which is also the point and the currents are so much less than what it takes to fault a breaker which could likely even sit in a mud puddle and remain energized.

 

[paul.nmedia.net]

I may have misunderstood one of the earlier posts but if a gfci trips on land only makes sense it would trip if something connected to it went in the water, what would be a bigger fault other than something connected by a ground wire? It works if it's fed 2 wire and it works for 2 wire equipment,,, which it the basic point, for use with ungrounded equipment but if it has 3 in and 3 out it is a direct pathway other than neutral. Which is also the point and the currents are so much less than what it takes to fault a breaker which could likely even sit in a mud puddle and remain energized.

A GFCI senses the difference in current flow between two different wires and trips if the difference is too great, 5 mA for the typical residential ones. A standard thermal magnetic breaker such as a 15 A miniature residential one trips at about 6-10 times it’s marked setting or 90-150 A for 15 A instantly via a magnetic coil. This is for dead shorts. Or over time down to about 80% of that so 12-15 A so you can surge much higher as in motor starting but sustained overloads trip it.

The impedance through bonding and grounding is much higher than through the main conductors (hot and neutral) so by nature it’s a lot less. Industrially it won’t hardly trip anything by the time you get to say a 100 HP. The connection between the grounded equipment housings (called bonding in Code) goes back to a single connection (system bonding jumper) at the service entrance. That’s also where the ground rod connects.

Code allows smaller wiring in the bonded circuit and allows steel and aluminum conduit, boxes, etc., to be part of the circuit. Since it only gets used during faults and theoretically even then for short periods this is all legal but a little corrosion totally eliminates it. Worse still is the practice of “peg grounding” which causes stray voltage and noise and interference in ground loops.

Typically when I measure it I get around 0.1-1 ohm with ground wiring like the ground wire in residential NM-B cable. It goes to around 3-10 ohms to the load in conduit if it’s new. With flexible metal conduit after a couple years it’s open. It measures 1.000-10.000 ohms...typical background/concrete and earth resistances with NO intentional grounding). So on a 15 A breaker at 12 A that’s about 120 V / 12 A = 10 ohms. So even in typical corroded up steel or aluminum conduit at a dock trying to get the breaker to trip even without passing through water is iffy at best. A ground rod is supposed to be under 25 ohms by Code. They vary a lot with soil but probably half of them are over 10 ohms.

What really happens is once everything gets melted and heated (welded) together from the arcing, you get a line-to-line (dead short) and then the breaker trips typically in under a second unless it’s a GFCI. Then just a heavy dew or fog will trip it. Nobody pays ground faults much respect in reality based on 25+ years of industrial experience.



Sent from my iPhone using Tapatalk

 

[yeldogt]

I have all of my exterior outlets/lights that are not connected to the house on GFI breakers -- don't want any possibility of any wires outside not being GFI protected. The outlets are not enough IMO.

Our boat is similarly protected -- you have to be more careful with the cords as any moisture will kill all your power. It too dangerous otherwise

 

[sberry]

I am fully aware how a gfci works.

 

[75gmck25]

With respect to water and electricity, you never know what can happen.

My brother's house flooded very quickly when rising water in the yard broke out a basement window and poured into the basement. Within 15 minutes he had about 6 feet of water in the basement, and most of his electrical panel was under water.

He was in the house at the time, but did not want to wade through 6 feet of water to shut anything off at the panel. However, it turned out that power upstairs remained on until the power company came out and shut power off at the pole or meter. Despite the basement panel being almost completely submerged in water, it did not trip the breakers.

Bruce

 

[paul.nmedia.net]

Overhead power lines are basically uninsulated. The pole has a ground wire running down it and the whole thing does not short out no matter how hard it rains. But put a little salt spray or acid or smoke on it and the insulators blow apart,


Sent from my iPhone using Tapatalk

 

[wyliesdiesels]

With respect to water and electricity, you never know what can happen.

My brother's house flooded very quickly when rising water in the yard broke out a basement window and poured into the basement. Within 15 minutes he had about 6 feet of water in the basement, and most of his electrical panel was under water.

He was in the house at the time, but did not want to wade through 6 feet of water to shut anything off at the panel. However, it turned out that power upstairs remained on until the power company came out and shut power off at the pole or meter. Despite the basement panel being almost completely submerged in water, it did not trip the breakers.

Bruce

The only breaker that shouldve tripped is the feeder breaker feeding that panel.

 

[alfredeneuman]

Pure water is non conductive.
Power Companies use deionized water to clean the insulators on energized high voltage towers without mishap
The various minerals make it conductive.

 

[rlitman]

The only breaker that shouldve tripped is the feeder breaker feeding that panel.

Not necessarily. Current could also flow across smaller breakers. The main terminals have greater physical separation, so the shortest path for current to flow would be between the terminals of a 2-pole breaker.

Pure water is non conductive.
Power Companies use deionized water to clean the insulators on energized high voltage towers without mishap
The various minerals make it conductive.

Sure, but flood water of any kind is VERY far from pure. Still, clearly it wasn't conductive enough to trip overcurrent protection. I guess it probably wasn't sea water.

That lack of conductivity is also an interesting danger. Because sea water is conductive, the voltage field across it when a live wire falls in the water is very small. The same cannot be said about fresh water, so not wading through the basement was a very wise choice.

Overhead power lines are basically uninsulated. The pole has a ground wire running down it and the whole thing does not short out no matter how hard it rains. But put a little salt spray or acid or smoke on it and the insulators blow apart,

Sometimes. Some municipalities use insulated wires.