GFCIs and EGCs

[Curious nerd]

In case there's anyone out there as ignorant as I am about "LCID"s but who's too shy to ask, here are some references. http://www.ecmag.com/section/codes-standards/differences-between-gfci-idci-and-gfpe http://ul.com/wp-content/uploads/2014/04/ul_GroundFaultProtectiveDevices.pdf

 

[mbrooke]

When my computer is on my desk in the office it(the power supply) is unlikely to be submerged, if I bring it to the kitchen that risk does increase - and is a major reason there is a GFCI in the kitchen and not the office.

Yes, but drop it into an insulated pool. Will the GFCI trip? If the sink has no copper plumbing? Will the GFCI trip?

 

[iwire]

Yes, but drop it into an insulated pool. Will the GFCI trip? If the sink has no copper plumbing? Will the GFCI trip?

And if I do drop it an a pool that is so well insulated that it can't trip a GFCI the only way I can get a shock is to open up that appliance and put myself across the line and neutral.


As always I call as I see them, you are either pulling our collective chain or you are nuts.

 

[Dennis Alwon]

Yes, but drop it into an insulated pool. Will the GFCI trip? If the sink has no copper plumbing? Will the GFCI trip?

If the cord is 2 wire and thrown into a sink of water that does not have a copper drain the gfci will not trip. If the cord is a 3 wire- has an egc then it will trip. I have done this experiment myself and in fact, put my hand into the water with the light that I submerged still burning. Added an egc to the water and pop the gfci tripped-- this is assuming the gfci has an egc.

Somehow I feel like you know this and are toying with us.

 

[romex jockey]

conjecture.......

conjecture.......

GFCI vs. EGC

Both are nice , but only one is a sure thing.

That the integrity of our EGC is not monitored on it's original install is strike one.

That bonding requirements are either missed, or are missed when other systems change from CU to PVC is strike two

That foreign appliances can hopscotch across our multitude of NRTLs until they enter this country is strike three

That HD , et all bog box appliance stores, allows for all God's special children to manifest the proceeding three lines i've wrote as they wish is the obvious motivation behind the NEC's rationale.

So instead of any grounding assurance plan (which only appears domestically via 590.6B2 )AND/OR mandating the one protective element in an all encompassing (descending magnitude) order at the service entrance to protect the entire shebang AND it's circuitry from it with maybe 3-4 of these>

We'll sell what is 20-30 (ave resi) of the smaller local point of use variety

It's unfortunate that we have such a tail wag dog approach....

~RJ~

 

[kwired]

Yes, but drop it into an insulated pool. Will the GFCI trip? If the sink has no copper plumbing? Will the GFCI trip?

No but if you put your hand in the water and you happen to be grounded to something - it likely does, though you will get a shock from the experience. GFCI's are not about preventing getting shocked, they are about limiting exposure though often times they do trip before one is exposed to much. This is why they also are acceptable for replacing non grounding receptacle outlets, sure having an EGC is better but it is about the best compromise available if you are not going to have an EGC.

 

[mbrooke]

And if I do drop it an a pool that is so well insulated that it can't trip a GFCI the only way I can get a shock is to open up that appliance and put myself across the line and neutral.


As always I call as I see them, you are either pulling our collective chain or you are nuts.

Inflatable pool. You will get a shock because your body will be in the voltage gradient. I know what your saying isn't so, because people have been killed and lawsuits filled because boat hulls in marinas have been energized and a voltage gradient formed some distance away. Same for pool lights. You are making it sound like water is a perfect insulator.

 

[mbrooke]

If the cord is 2 wire and thrown into a sink of water that does not have a copper drain the gfci will not trip. If the cord is a 3 wire- has an egc then it will trip. I have done this experiment myself and in fact, put my hand into the water with the light that I submerged still burning. Added an egc to the water and pop the gfci tripped-- this is assuming the gfci has an egc.

Somehow I feel like you know this and are toying with us.

That's exactly my point, at least part of it!

I am not toying, but then again you did call a very serious matter a troll post once

I still am having trouble understanding if absent EGC are what really got GFCIs into the code.

 

[kwired]

Inflatable pool. You will get a shock because your body will be in the voltage gradient. I know what your saying isn't so, because people have been killed and lawsuits filled because boat hulls in marinas have been energized and a voltage gradient formed some distance away. Same for pool lights. You are making it sound like water is a perfect insulator.

With something like an inflatable pool you also create a capacitor with the pool liner/shell being the insulator between two conductors - earth and water, AC current flows through a capacitor, just the current is out of phase with the source, DC current charges the capacitor and then nothing else happens as long as applied voltage doesn't change.

 

[mbrooke]

No but if you put your hand in the water and you happen to be grounded to something - it likely does, though you will get a shock from the experience. GFCI's are not about preventing getting shocked, they are about limiting exposure though often times they do trip before one is exposed to much. This is why they also are acceptable for replacing non grounding receptacle outlets, sure having an EGC is better but it is about the best compromise available if you are not going to have an EGC.

That's correct, but if the person is in the pool or tub a GFCI will not trip while a danger still exists.


So here GFCIs have a limitation...

 

[iwire]

Inflatable pool. You will get a shock because your body will be in the voltage gradient. I

Explain.

In I am or out of this pool?

If I am in the pool and it is so insulated from ground it wont trip a GFCI I cannot get a shock without getting between line and neutral.

If you disagree with that you will need to explain how current will flow.

know what your saying isn't so, because people have been killed and lawsuits filled because boat hulls in marinas have been energized and a voltage gradient formed some distance away.

That is an entirely different scenario then the pool example and those hulls should have been grounded correct?

Same for pool lights. You are making it sound like water is a perfect insulator.

And again that is not the same as the example of a two wire cord dropped in a insulated pool.

Now you seem to be talking about an energized pool light housing which is already code required to be bonded to the equal-potential grounding grid.

 

[mbrooke]

With something like an inflatable pool you also create a capacitor with the pool liner/shell being the insulator between two conductors - earth and water, AC current flows through a capacitor, just the current is out of phase with the source, DC current charges the capacitor and then nothing else happens as long as applied voltage doesn't change.

That is true, and something that would take place in a very large pool. But if the pool is smaller (think in box inflatable)?

 

[iwire]

With something like an inflatable pool you also create a capacitor with the pool liner/shell being the insulator between two conductors - earth and water, AC current flows through a capacitor, just the current is out of phase with the source, DC current charges the capacitor and then nothing else happens as long as applied voltage doesn't change.

That's correct, but if the person is in the pool or tub a GFCI will not trip while a danger still exists.


So here GFCIs have a limitation...

Yes GFCIs have limitations, OCPDs have limitations, EGCs have limitations.

Your proposed solution is to remove a level of protection so again it seems you are pulling our chain or simply mistaken in your thinking.

 

[mbrooke]

Explain.

In I am or out of this pool?

If I am in the pool and it is so insulated from ground it wont trip a GFCI I cannot get a shock without getting between line and neutral.

If you disagree with that you will need to explain how current will flow.

Ok I will sacrifice myself for this one I am in the pool, its a small inflatable rubber insulated pool and a 2 wire hair dryer gets dropped in. GFCI outlet.


My theory is I will still get a shock or be killed without taking the hair dryer apart. Why? Water is conductive to a degree. The water will conduct power line to neutral forming a voltage gradient across the water. I could be in that path.

That is an entirely different scenario then the pool example and those hulls should have been grounded correct?

It proves a point electricity can travel across water.

And again that is not the same as the example of a two wire cord dropped in a insulated pool.

Now you seem to be talking about an energized pool light housing which is already code required to be bonded to the equal-potential grounding grid.

It is required to be part of the grid yes, but I am talking about cases where it was no. And FWIW an equal potential grid not only helps a GFCI operate but may reduce the voltage gradient.

 

[mbrooke]

Yes GFCIs have limitations, OCPDs have limitations, EGCs have limitations.

Your proposed solution is to remove a level of protection so again it seems you are pulling our chain or simply mistaken in your thinking.

Nope, add more protection. Think EGC everywhere and LCID on all 2 prong appliances that could be submerged.

 

[kwired]

That is true, and something that would take place in a very large pool. But if the pool is smaller (think in box inflatable)?

Back in the days when waterbeds were popular I remember laying on bed with no sheets and touching grounded baseboard heater and getting a tingle (because of the heater under the waterbed) but it went away if the heater was unplugged. Thought we had a bad heater, replaced it and nothing changed - probably was capacitive effects is my conclusion. This bed was on a wood frame and was well isolated electrically from other grounded objects other then the baseboard heater (not electric but hydronic) as within reach.

Ok I will sacrifice myself for this one I am in the pool, its a small inflatable rubber insulated pool and a 2 wire hair dryer gets dropped in. GFCI outlet.


My theory is I will still get a shock or be killed without taking the hair dryer apart. Why? Water is conductive to a degree. The water will conduct power line to neutral forming a voltage gradient across the water. I could be in that path.








It proves a point electricity can travel across water.






It is required to be part of the grid yes, but I am talking about cases where it was no. And FWIW an equal potential grid not only helps a GFCI operate but may reduce the voltage gradient.

You could be in that path, whether or not enough current flows through critical places to kill you is questionable, but I'm not going to try it to find out either. Voltage gradient (outside of capacitive effects) is going to be very near the appliance dropped in the water and will diminish pretty rapidly if no other point of potential is nearby.

 

[mbrooke]

Back in the days when waterbeds were popular I remember laying on bed with no sheets and touching grounded baseboard heater and getting a tingle (because of the heater under the waterbed) but it went away if the heater was unplugged. Thought we had a bad heater, replaced it and nothing changed - probably was capacitive effects is my conclusion. This bed was on a wood frame and was well isolated electrically from other grounded objects other then the baseboard heater (not electric but hydronic) as within reach.


You could be in that path, whether or not enough current flows through critical places to kill you is questionable, but I'm not going to try it to find out either. Voltage gradient (outside of capacitive effects) is going to be very near the appliance dropped in the water and will diminish pretty rapidly if no other point of potential is nearby.

But still, that gradient can reach long enough, and far out enough to cause harm if not kill. If its true that immersion in water is not a concern, that would absolutely then tell me the only reason GFCIs came about is because of open EGCs or a lack of them that still continues to this day. And I have a theory regarding toasters why that may be...


Any way, EGC with GFCI vs none EGC with GFCI (or at least demonstrating that concept) Big difference:

https://www.youtube.com/watch?v=XEYvI2jrwDg

 

[romex jockey]

fwiw

fwiw

The medical society was solicited over 40 years ago to decipher what electrical levels would put an adult heart into Vfib. This is where the 4-6 ma comes from, But this is across the heart, NOT alternate paths nor that which assumes multiple paths. Our domestic OCPD's also employ magnetic trip levels X5 of our euro counterparts

This is, when one strip away the entire debate, what GFCI protection is all about, as well as any step potential one would interject.

The obvious end game here is a patent EGC. That it remains an unmonitored entity in the USofA , other than that which amounts to NEC hubris, is why gfci protection is sanctioned as a default protectant.

~RJ~

 

[mbrooke]

The medical society was solicited over 40 years ago to decipher what electrical levels would put an adult heart into Vfib. This is where the 4-6 ma comes from, But this is across the heart, NOT alternate paths nor that which assumes multiple paths.

This is, when one strip away the entire debate, what GFCI protection is all about.

The obvious end game here is a patent EGC. That we do not have one in the USofA , other than that which amounts to NEC hubris, is why gfci protection is sanctioned as a default protectant.

~RJ~

Searching different forums I just came across this, which is thought provoking imo. Never knew that:


http://www.electriciansforums.co.uk...rum/101678-kitchen-sockets-2.html#post1096256

 

[Curious nerd]

But still, that gradient can reach long enough, and far out enough to cause harm if not kill.

Here's why you're right. The current flow between hot and neutral in the immersed appliance will take all possible paths. Every drop of chlorinated tap water in the pool is part of a (poorly) conductive path. So is any human in the pool. Even though most of the current will flow inside the appliance not all of it will.