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Old 02-10-2015, 08:38 PM   #21
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Gfci protect people grounding protects equipmemt.
Equipment grounding most certainly protects people.
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Old 02-10-2015, 11:13 PM   #22
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Old 02-10-2015, 11:27 PM   #23
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Gfci protection doesn't hurt but i don't believe it should be mandatory for everything. I added two garage door opener outlets last night., they were 11' high. I loaded them from the sprinkler gfci outlet. But really, what safety is gained here by having the door openers protected if they are grounded?
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Old 02-11-2015, 03:00 AM   #24
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Old 02-11-2015, 07:06 AM   #25
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Someone can easily get electrocuted by a fault that doesn't trip a breaker. You could have voltage going to ground and not trip a breaker.
I just had ceu class last week and the instructor asked a similar question. Although his argument was better than mine.
The breaker protects the wire the equipment ground protects the equipment and gfci protects people. Not saying that the equipment ground doesn't protect people in clearing any faults but it is very possible to still get electrocuted with it. And it goes back to your question, which do you trust more..?
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Old 02-11-2015, 09:14 AM   #26
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Equipment ground.

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Old 02-11-2015, 09:35 AM   #27
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If equipment ground is for life safety then why do we install GFCI s?
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Old 02-11-2015, 12:35 PM   #28
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Originally Posted by captkirk View Post
Someone can easily get electrocuted by a fault that doesn't trip a breaker. You could have voltage going to ground and not trip a breaker.
I just had ceu class last week and the instructor asked a similar question. Although his argument was better than mine.
The breaker protects the wire the equipment ground protects the equipment and gfci protects people. Not saying that the equipment ground doesn't protect people in clearing any faults but it is very possible to still get electrocuted with it. And it goes back to your question, which do you trust more..?
Nope, it protects people and property. A GFCI enhances an EGC or where it may fail to protect such as an appliance in water.
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Old 02-11-2015, 12:40 PM   #29
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I think you missed my point. The only reason you need a GFCI is because you have a grounded system. Without a grounded system, the shock hazard drops tremendously. I believe that's the main reason they use isolated ground systems in operating rooms, to significantly reduce shock hazards.

If you don't have a grounded system, you really don't need a GFCI. It's not a choice of A over B, it's you need B because of A.
I believe ungrounded systems in operating rooms were mainly established to eliminate the chance of a spark of a ground fault causing an explosion. This used to be a huge problem long long ago. This of course doesn't help if there were a line-line fault, but according to data, ground faults are much more common than line-line faults.

Equipment grounds ensure the breaker will trip on ground fault assuming you have an effective ground fault current path back to the breaker. It's also going to take an average circuit breaker several cycles to trip that breaker, meaning that the full fault current is flowing on that circuit for maybe 50ms.

If I was part of that circuit, my body is going to experience all of that current. I don't want my body to ever be a ground fault path, but if it was, I would prefer that a GFCI be there to trip at 4-6mA rather than the circuit breaker letting through 50-100A best case scenario.
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Old 02-11-2015, 12:47 PM   #30
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Originally Posted by captkirk View Post
If equipment ground is for life safety then why do we install GFCI s?


3 main NEC reasons:

1. An EGC can break open and fail to protect. Thus, if an appliance frame became live it would sense a leakage going through a person or something else and disconnect the power.

2. Submerging something in water (most of the time anyway*). Water will not conduct enough power to trip a breaker, but can conduct power to a person. Such a scenario is a drill in a sink or bucket of water and a person reaches to in to grab it while feet on concrete or conductive surface.

* IF one had a fully insulated pool from ground and a 2 wire toaster was dropped in it with people swimming the GFCI would not trip. Ground your pool water folks

3. A damaged extension cord with exposed conductors. Should it end up in a puddle of water or a person was to grab the frayed cord the GFCI will most likely trip.

Reasons at the branch circuit level (though not required by the NEC directly)

1. Detecting dangerous wiring errors or faults. Any fault to ground such as romex pierced by a nail will trip differential (GFCI) protection, which is why 80% of AFCI have it but just set to a higher degree such as 30 or 50ma instead of 5.
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Old 02-11-2015, 12:55 PM   #31
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I've had several calls over the years in which people said they were getting shocked from certain appliances in their homes. Two things they all had in common were they all had egc and no gfci.
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Old 02-11-2015, 01:00 PM   #32
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And like I said EGC is not life safety so what are we debating now
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Old 02-11-2015, 01:03 PM   #33
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I've had several calls over the years in which people said they were getting shocked from certain appliances in their homes. Two things they all had in common were they all had egc and no gfci.
What was did the issue end up being?
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Old 02-11-2015, 01:19 PM   #34
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[quote=meadow;1653137]3 main NEC reasons:



3. A damaged extension cord with exposed conductors. Should it end up in a puddle of water or a person was to grab the frayed cord the GFCI will most likely trip.


Debatable.
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Old 02-11-2015, 01:29 PM   #35
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What was did the issue end up being?
One of them was a detached garage feeder with 2 cloth type conductors (rigid conduit as egc) feeding the outlets and lights in the garage the guy had a fridge that had current on the shell. Over the years the pipe corroded and the conductors fused to the pipe and was leaking current into the egc. If there was a gfci in the outlet it would have undoubtedly tripped but it was just a regular outlet.
The other one was much more serious. A metal pipe in a parking garage had corroded and the conductors leaked 277 volts into the ground. Didn't trip the breaker but when the maintenance guy went to change lamps he got the **** knocked out of him.
And I had an old window ac that had current on the shell. Defective unit and the breaker didn't trip.
I do a lot of service work so Ive seen a lot of **** over the years.
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Old 02-11-2015, 01:32 PM   #36
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One of them was a detached garage feeder with 2 cloth type conductors (rigid conduit as egc) feeding the outlets and lights in the garage the guy had a fridge that had current on the shell. Over the years the pipe corroded and the conductors fused to the pipe and was leaking current into the egc. If there was a gfci in the outlet it would have undoubtedly tripped but it was just a regular outlet.
The other one was much more serious. A metal pipe in a parking garage had corroded and the conductors leaked 277 volts into the ground. Didn't trip the breaker but when the maintenance guy went to change lamps he got the **** knocked out of him.
And I had an old window ac that had current on the shell. Defective unit and the breaker didn't trip.
I do a lot of service work so Ive seen a lot of **** over the years.


If the conduit was after a GFCI it would have.


The down side to breakers is that they fail to catch high resistance faults. What few will say is that short circuits will don't just happen, usually they start as a high resistance fault and progress until the leakage current trips the breaker.

Last edited by meadow; 02-11-2015 at 01:34 PM.
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Old 02-11-2015, 01:32 PM   #37
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[quote=bobelectric;1653297]
Quote:
Originally Posted by meadow View Post
3 main NEC reasons:



3. A damaged extension cord with exposed conductors. Should it end up in a puddle of water or a person was to grab the frayed cord the GFCI will most likely trip.


Debatable.

The reason or the GFCI will trip?
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Old 02-12-2015, 09:04 PM   #38
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I dont put a lot of faith in GFCI's. I was doing a remodel on a pool that had old abandoned conduits stubbed up for pole lights and outlets on columns around the pool. In one column they had 3 3/4" pvc stubbed up. They all had duct tape which I figured a co worker had done previously to protect against debris during demo. I stuck my razor knife in one to cut the tape off the conduit and took a ride. Later found out that it was on a GFCI receptacle wired on the load side that was feeding a well pump someone had hacked into to add a receptacle on the column. All other circuits where in a dedicated sub panel for the pool that had been shut off. Ive had first hand experience of a GFCI failing to do its job.
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Old 02-12-2015, 10:06 PM   #39
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If I was in a pool area I would sure as hell hope there was a gfci on it. Egc wouldn't do anything..
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Old 02-12-2015, 10:10 PM   #40
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If I was in a pool area I would sure as hell hope there was a gfci on it. Egc wouldn't do anything..
An EGC would help trip the GFCI if the pool was ungrounded.
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