A/C Outlet Underwater

[onewheat]

I have a power pole for my dock that recently became submerged when the lake level came up about 13' over a couple days. It is the highest I have ever seen the lake - ANYWAY, it totally cooked the GFCI in the box on the pole, but did NOT trip the breaker. I was wondering, how that is possible? I killed the power to that branch and this weekend replaced the GFCI and everything is good again - but what's up with the breaker? Is that typical, possible, or what would the reason be? It is a 20A circuit and this one outlet is the only thing on it and it was definitely 6" - 12" underwater for a couple days.

 

[Shiftless]

I am certainly not an electrician but I suppose that the breaker didn't trip because the current leakage to ground through the water was less than 20 amps. Fresh water is not a really great conductor.
You might want to test that breaker to make sure it is operational.

 

[grantw]

I am certainly not an electrician but I suppose that the breaker didn't trip because the current leakage to ground through the water was less than 20 amps. Fresh water is not a really great conductor.
You might want to test that breaker to make sure it is operational.

Most likely the case.

http://www.electroboom.com/?p=397

 

[tyme2par4]

Is the breaker a GFCI breaker? Because it probably should be.
It sounds like the GFCI outlet did it's job and tripped itself properly, but the current leakage was minimal through the water, so it didn't trip the breaker. This is a serious hazard, as if anyone had gone into the water, they could have been electrocuted.

 

[onewheat]

I'm sure there were dozens of outlets underwater in our cove and probably thousands in the lake. It was a recently unprecedented water level. My outlet is about 1027' and the lake 'normally' is at 1020' at full pool although I have seen it at 1023' since we have built - but that was still a long way from our power pole. Four more feet on a 32,000+ acre lake is a LOT of water. It is NOT a GFCI breaker. It is a double breaker in that slot. Do those come GFCI or only in singles? If they do, I can have it changed out.

 

[wyliesdiesels]

I'm sure there were dozens of outlets underwater in our cove and probably thousands in the lake. It was a recently unprecedented water level. My outlet is about 1027' and the lake 'normally' is at 1020' at full pool although I have seen it at 1023' since we have built - but that was still a long way from our power pole. Four more feet on a 32,000+ acre lake is a LOT of water. It is NOT a GFCI breaker. It is a double breaker in that slot. Do those come GFCI or only in singles? If they do, I can have it changed out.

The breaker should be a single pole breaker not a double.

What brand of breaker is it?

Yes you can get single pole GFCI breakers but u have a GFCI outlet protecting the outlet so it should be fine.

I would not go in that lake as u could get electrocuted...

 

[onewheat]

I'm not sure if I am using the correct terminology - it is a two single breakers in a single slot - like half width. Is that double pole? It's like the one pictured but 20A and my power pole is on one of those breakers - but not GFCI. I'm not sure of the brand - it is 3.5 hours from here. The lake level has dropped and the water is well away from the pole now. The water is just above summer pool level.

 

[ddawg16]

That is a tandem breaker....I have a few of those in my load center.

You treat it as two separate breakers...but at the same voltage.

 

[ishiboo]

That's a tandem.

I would definitely put it on a GFCI breaker with those kind of water problems.

 

[rlitman]

I am certainly not an electrician but I suppose that the breaker didn't trip because the current leakage to ground through the water was less than 20 amps. Fresh water is not a really great conductor.
You might want to test that breaker to make sure it is operational.

This. A GFCI breaker, or another GFCI upstream in the circuit in a location that cannot be submerged would be a good safety addition.

Are the wires solid or stranded? Stranded wires will wick up water, and you may have long-term issues with corrosion. Especially if they're not tinned (which is why tinned wires are the norm in marine use).

 

[onewheat]

It is a single cable - 12 GA solid with 3 strands (hot, neutral and ground) that comes from the breaker box to the pole - all buried. It is the only outlet on the circuit and just supplies power to the dock for the boat lift and a couple lights and outlets.

 

[tyme2par4]

Any circuit that could potentially come in contact with a body of water should be protected prior to where it may contact the water. In your case, during normal levels, the outlet will suffice, but as you have seen, in high water situations, it becomes a serious hazard. The circuit should definitely be protected at the panel.
Also, if this is an underground circuit it would be advisable to have GFCI protection at the panel as well.

I don't believe you will find a tandem GFCI breaker, but unless your panel is completely full of tandems, you can simply swap the wire with another single breaker, and swap that breaker with a GFCI.

 

[Shiftless]

rlitman has the best advice. That is what should be done. Your solid wire 12 ga. cable ( UF right?) will be fine. If is is NOT UF, yank it all out.

 

[onewheat]

It is direct-burial wire (is that UF?). It was all inspected and up to code in 2012 when we built. I'll have to check the box to see if I have a single breaker I could swap with or call my electrician to inquire as to why it was done the way that it was.

 

[grantw]

...This is a serious hazard, as if anyone had gone into the water, they could have been electrocuted.

Within a small radius of that one outlet that has a neutral and ground wire within a few inches of the 120VAC line, possible. see my link to the electroboom blog above. I could list a whole list of why it's not THAT dangerous to have a single submerged outlet in "fresh" water, but will probably get lost in forum flaming and minutia.

Easy solution, replace the feed breaker with a GFCI type, and inspect the wire for corrosion in a few months after replacing the toasted GFCI outlet.

 

[tyme2par4]

It is direct-burial wire (is that UF?). It was all inspected and up to code in 2012 when we built. I'll have to check the box to see if I have a single breaker I could swap with or call my electrician to inquire as to why it was done the way that it was.

If it is not in conduit, I believe GFCI is required. In conduit, not required.

Within a small radius of that one outlet that has a neutral and ground wire within a few inches of the 120VAC line, possible. see my link to the electroboom blog above. I could list a whole list of why it's not THAT dangerous to have a single submerged outlet in "fresh" water, but will probably get lost in forum flaming and minutia.

Easy solution, replace the feed breaker with a GFCI type, and inspect the wire for corrosion in a few months after replacing the toasted GFCI outlet.

It's called Electric Shock Drowning or ESD, and it is a very real and very dangerous problem.
http://www.boatus.com/seaworthy/magazine/2013/july/electric-shock-drowning-explained.asp

Yes, if the ground wire was still intact at the outlet, the danger is minimal, but without a functional GFCI at the source, you have no knowledge of whether or not there is a break in the ground.

 

[rlitman]

...I could list a whole list of why it's not THAT dangerous to have a single submerged outlet in "fresh" water, but will probably get lost in forum flaming and minutia...

Not flaming, but some minutia here. Fresh water is worse BECAUSE it is less conductive. Salt water is more conductive than your body, so you will not experience an electric potential while in the water. Fresh water is the opposite, and current will end up flowing through you.

That being said, if this were in a metal box with a metal cover, and it was all grounded, I don't see much potential for an electric field to escape. But I still would feel more comfortable with upstream GFCI protection.

The direct burial wire is fine. So yeah, it is probably UF (or equivalent). I just wanted to make sure it was not stranded THHN in conduit. THWN may be rated for the insulated wire to be in wet locations, but the bare ends still should not get wet.

There are now weather resistant GFCI outlets out there. They have conformal coatings on the circuitry and plating on the metal to resist corrosion. But I still would not want to see one submerged.

 

[grantw]

...That being said, if this were in a metal box with a metal cover, and it was all grounded, I don't see much potential for an electric field to escape. But I still would feel more comfortable with upstream GFCI protection...

This was the scenario I had in my head when I posted my reply.

 

[Shiftless]

tyme2par4:
Current code requires 120 volt receptacles of 20 amps to be GFCI protected whether or not they are in conduit.

 

[onewheat]

The receptacle is currently GFCI protected (just not GFCI Breaker protected) and I don't remember whether the entire run is in conduit or not. I saw the trench and remember them running it but my memory is becoming worse than my eyesight lately, and I just don't recall. Whatever they required in TN in 2012 is how it is. I know it was inspected and it passed.

 

[wyliesdiesels]

Unfortunately, a GFCI will most likely not trip under the OPs circumstances.

This is due to the way GFCIs work...

The hot and neutral underwater doesnt provide a current imbalance so the GFCI is not gonna trip.

The GFCI cooked because the internal electronics got shorted...

On the off chance the ground has a better path back to the neutral bar in the panel, the GFCI would trip.

Unfortunately, its rarely the case and many people get electrocuted near lake docks due to submerged outlets...

There is a device one can get that detects this dangerous situation....I dont remember who makes it....

Mike holt(IIRCC) did a video of himself dunking a hair dryer plugged into a GFCI outlet with a GFCI plug on the end of the cord, turned it on and it didnt trip either GFCI. I wish i could find the video...

 

[wyliesdiesels]

I have a power pole for my dock that recently became submerged when the lake level came up about 13' over a couple days. It is the highest I have ever seen the lake - ANYWAY, it totally cooked the GFCI in the box on the pole, but did NOT trip the breaker. I was wondering, how that is possible? I killed the power to that branch and this weekend replaced the GFCI and everything is good again - but what's up with the breaker? Is that typical, possible, or what would the reason be? It is a 20A circuit and this one outlet is the only thing on it and it was definitely 6" - 12" underwater for a couple days.

The breaker didnt trip because the water provided enough resistance to act as a load and the resistance was high enough that there wasnt a dead short.

In order for a breaker to trip, it would either need to see an overcurrent above its rating, or for a short circuit, no resistance and thousands of amps.

The GFCI cooked simply because the electronics got submerged...

Is the breaker a GFCI breaker? Because it probably should be.
It sounds like the GFCI outlet did it's job and tripped itself properly, but the current leakage was minimal through the water, so it didn't trip the breaker. This is a serious hazard, as if anyone had gone into the water, they could have been electrocuted.

A GFCI breaker would not provide any additional protection here.

An the GFCI cooked not tripped.

That's a tandem.

I would definitely put it on a GFCI breaker with those kind of water problems.

wont do any good since there is no other pathway for the current to become imbalanced between hot and neutral...

This. A GFCI breaker, or another GFCI upstream in the circuit in a location that cannot be submerged would be a good safety addition.

wont make a difference unless there is an alternate path to ground in the panel.

The current will travel right through the person in the body of water and back to the neutral...

Within a small radius of that one outlet that has a neutral and ground wire within a few inches of the 120VAC line, possible. see my link to the electroboom blog above. I could list a whole list of why it's not THAT dangerous to have a single submerged outlet in "fresh" water, but will probably get lost in forum flaming and minutia.

Easy solution, replace the feed breaker with a GFCI type, and inspect the wire for corrosion in a few months after replacing the toasted GFCI outlet.

Not true. People are electrocuted in this exact scenario all the time after they jump into the lake.

Someone the Electrical code discussion group on facebook recently posted an article about a girl who was electrocuted in this exact scenario...

If it is not in conduit, I believe GFCI is required. In conduit, not required.


It's called Electric Shock Drowning or ESD, and it is a very real and very dangerous problem.
http://www.boatus.com/seaworthy/magazine/2013/july/electric-shock-drowning-explained.asp

Yes, if the ground wire was still intact at the outlet, the danger is minimal, but without a functional GFCI at the source, you have no knowledge of whether or not there is a break in the ground.

Conduit doesnt negate the need for a GFCI...

And the ground wire doesnt provide any additional protection.

And GFCIs dont monitor or care about intact ground wires. A GFCI can function perfectly fine WITHOUT a ground wire attached to the ground terminal. This is because a GFCI only monitors the current on hot and neutral...

Not flaming, but some minutia here. Fresh water is worse BECAUSE it is less conductive. Salt water is more conductive than your body, so you will not experience an electric potential while in the water. Fresh water is the opposite, and current will end up flowing through you.

That being said, if this were in a metal box with a metal cover, and it was all grounded, I don't see much potential for an electric field to escape. But I still would feel more comfortable with upstream GFCI protection.

The direct burial wire is fine. So yeah, it is probably UF (or equivalent). I just wanted to make sure it was not stranded THHN in conduit. THWN may be rated for the insulated wire to be in wet locations, but the bare ends still should not get wet......

Unless there is enough fault current flowing between the hot and the metal box, the breaker wont trip. And obviously in the OPs case there wasnt.

THWN is rated for wet locations...

 

[AntonLargiader]

I think when it comes to water and the outdoors, the right thing to do is protect the entire circuit, not just the receptacle load. I put my outdoor receptacle on a CAFI breaker to avoid the exact scenarios that we've seen twice here within the week (water ingress). A GFCI receptacle only protects what's plugged into it.

 

[AntonLargiader]

Wylie, I'm not sure why you are thinking all of the current is going to selectively find its way back via the neutral rather than going to ground via the ground circuit (which has much more exposure to the water) or somewhere else. Yes, you can make a scenario where dunking a device into water doesn't create a ground fault but when an entire lake is part of your fault path I think some current is going to escape.

The GFCI recep doesn't work in the immersion scenario because it doesn't interrupt the bare wires connected to the terminals. Shutting off the blades in the recep doesn't solve that problem.

 

[tyme2par4]

Unfortunately, a GFCI will most likely not trip under the OPs circumstances.

This is due to the way GFCIs work...

The hot and neutral underwater doesnt provide a current imbalance so the GFCI is not gonna trip.

The GFCI cooked because the internal electronics got shorted...

On the off chance the ground has a better path back to the neutral bar in the panel, the GFCI would trip.

Unfortunately, its rarely the case and many people get electrocuted near lake docks due to submerged outlets...

There is a device one can get that detects this dangerous situation....I dont remember who makes it....

Mike holt(IIRCC) did a video of himself dunking a hair dryer plugged into a GFCI outlet with a GFCI plug on the end of the cord, turned it on and it didnt trip either GFCI. I wish i could find the video...

How would a GFCI not help? It's job is to detect a difference in current between the hot and neutral. In a case where the hot wire is submerged, you will get some leakage of current to ground, which will cause a GFCI breaker to trip. The exception would be if the hot an neutral form a short, in which case the breaker would trip on over current.

The hair dryer example is irrelevant, because a bucket of water is different than a lake. That bucket of water is insulated from ground, so there is nowhere for the current to go, other than back up the neutral wire.

Conduit doesnt negate the need for a GFCI...

And the ground wire doesnt provide any additional protection.

And GFCIs dont monitor or care about intact ground wires. A GFCI can function perfectly fine WITHOUT a ground wire attached to the ground terminal. This is because a GFCI only monitors the current on hot and neutral...

My mistake, for some reason I was thinking GFCI wasn't required for metallic conduit on only 15A.

I realize GFCIs don't monitor the ground. My comment was simply stating that the ground wire would be the easiest path for current to flow, as it would be the closest thing to the hot wire, and would have a direct path to the GEC. Copper wire has a lot lower resistance than fresh water.

 

[AntonLargiader]

FWIW the 2017 NEC 555.3 requires GFCI at the OCPD not exceeding 30mA. This applies to pretty much every docking facility including those at private residences. The BoatUS article on ESD listed this as the second most important thing you can do (behind something that doesn't apply to this scenario).

 

[barnjunkie]

My water well and fish pond pumps are submerged and both run on 220V. No tripped breaker here (and happy about it).

 

[onewheat]

FWIW the 2017 NEC 555.3 requires GFCI at the OCPD not exceeding 30mA. This applies to pretty much every docking facility including those at private residences. The BoatUS article on ESD listed this as the second most important thing you can do (behind something that doesn't apply to this scenario).

Umm... what? Can you dumb that down for the layman?

 

[rlitman]

Umm... what? Can you dumb that down for the layman?

1) It's a new rule that is probably not in force for you yet, though still a very good idea
2) A GFCI outlet trips at 4-6mA of current, so it already exceeds this requirement, however, the new code requires that the BREAKER feeding a dock be GFCI, and meet a minimum standard.

For your purposes, i.e. a single phase 120V 15 or 20A breaker, there is only one ground fault current rating available. Where the rule really comes into play is when a large breaker feeds a panel at a dock.

TL;DR, replace the breaker feeding that outlet with a GFCI breaker. The, if you want, you can then just use a regular outlet there and not throw out as much money if it floods again.

 

[AntonLargiader]

The BoatUS article focused heavily on shore power to boats, and the main recommendation was the use of isolation transformers (which doesn't apply here). But the next recommendation was GFCI at the breaker level which completely applies here. The 2017 NEC requires GFCI at the breaker for docks, although the adoption of the 2017 code is probably pretty small at this point. Still a good idea, though.

 

[wyliesdiesels]

How would a GFCI not help? It's job is to detect a difference in current between the hot and neutral. In a case where the hot wire is submerged, you will get some leakage of current to ground, which will cause a GFCI breaker to trip. The exception would be if the hot an neutral form a short, in which case the breaker would trip on over current.

The hair dryer example is irrelevant, because a bucket of water is different than a lake. That bucket of water is insulated from ground, so there is nowhere for the current to go, other than back up the neutral wire......

Im just not convinced that the current would go to the EGC vs. the neutral...

It may very well and then the GFCI would trip and I would be wrong.

Perhaps someone has done a test to test this out....

 

[Orionrising]

Wire a float switch to a plug so that it shorts the circuit when floating. Mount below level of electrical line... Automatic breaker flipper.

Sent from my Moto G (4) using Tapatalk

 

[Syberia]

Im just not convinced that the current would go to the EGC vs. the neutral...

It may very well and then the GFCI would trip and I would be wrong.

Perhaps someone has done a test to test this out....

I've accidentally dropped the end of an extension cord in a puddle of water and the GFCI it was plugged into tripped instantly. Seems to be almost the same scenario you're describing.

 

[tyme2par4]

Im just not convinced that the current would go to the EGC vs. the neutral...

It may very well and then the GFCI would trip and I would be wrong.

Perhaps someone has done a test to test this out....

Because water is not a great conductor, you are never going to see 100% of the current go directly from hot to neutral. It only takes a small difference in the current between hot and neutral to trip a GFCI.

 

[mobiledynamics]

bump....


I have a new outdoor panel where our hvac sits on our rooftop.
It's mounted on strut.
I sealed the inside holds on the back panel where one would mount.

There's also a bell box for a *service outlet*.

Is it good pratice to seal/caulk the top of the screw hole on the bell box.
Re: the load panel, I have 2 connections on L and Right. Good pratice to run a small bead of caulk either on the *top* of where the connection is on the side of the box ?

 

[AntonLargiader]

There's a public comment period running from now to December 21st regarding a proposed change. The change adds piers to the scope of the existing regulation which is currently worded to apply to docking facilities.

One thing I don't understand is why the section only applies to 15A and 20A circuits. A quick search showed that many boat hoists are 30A, and 30A GFCI breakers are available. Seems very reasonable to include 30A in the scope.

http://www.ecmweb.com/national-electrical-code/tia-related-bodies-water

 

[sberry]

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.

 

[ard]

One thing I don't understand is why the section only applies to 15A and 20A circuits. A quick search showed that many boat hoists are 30A, and 30A GFCI breakers are available. Seems very reasonable to include 30A in the scope.

Wouldn't that be included in (B) "feeder and branch circuit conductors"??

 

[AntonLargiader]

Wouldn't that be included in (B) "feeder and branch circuit conductors"??

Yes. I was not reading it properly. Thanks!

 

[ard]

and who know that the Electrical Datum Plane is 24" above either the water height or, if tidally influenced, the maximum water height....