GFCI Outlet Question

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Originally Posted By: Bob Badger
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Reading another topic here made me think of a question to ask HIs.


Will a GFCI device prevent an electrical shock?

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Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

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Originally Posted By: jpeck
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NO.


It will help limit it though. Limit it to a low enough shock to (hopefully) not be fatal.

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Jerry Peck
South Florida

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Originally Posted By: Bob Badger
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I would say Jerry’s answer is as good as it gets.


I think that information is important to remember.

It is much better to prevent contact with an electrical source than it is to count on a GFCI device.

I am very much in favor of of GFCIs but I think that people think these units prevent shocks, most times that is not the case.

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Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

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Originally Posted By: Lew Lewis
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It is much better to prevent contact with an electrical source than it is to count on a GFCI device.


Bob,

Not everyone is using common sense to avoid the electrical source.

Yesterday my wife was messing with the fish tank when the flourescent light fell into the tankful of water and was immersed(the light was ON). She immediately stuck her hand in the tank to retrieve the light. I immediately pulled the plug. No harm done and I managed to calmly tell her to use common sense next time. Maybe we need whole house GFCI protection!

Neal

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Originally Posted By: ekartal
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Shuts off the current off in 1/20 th of a milisecond or something like that.


Erol Kartal
ProInspect

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Originally Posted By: Bob Badger
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Lew I am glad your wife was unharmed none of us are immune to lapses in common sense.


Years ago I was trouble shooting some three way switches for a 277 volt lighting circuit, live of course  I got whacked hard, being the stubborn guy I am instead of stopping what I was doing I jumped right back in and got whacked again, even harder.

Not much common sense in trying to out tough electricity. 

As for whole house protection with GFCIs IMO that would be a great idea, keeping in mind prevention is still better.

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Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

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Originally Posted By: Bob Badger
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ekartal wrote:

Shuts off the current 1/20 th of a milisecond or something like that.

0.025 of 1 second and if my math is correct about 2 'cycles' of 60 Hz AC, definitely fast but not faster then you feel it.

I do not recommend doing this but if you have ever seen a GFCI protected circuit fault to ground you can not really tell from the size of the arc flash that it had GFCI protection, it still takes a mighty bite out of a screwdriver. 

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Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

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Originally Posted By: jpeck
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Bob Badger wrote:

As for whole house protection with GFCIs IMO that would be a great idea, keeping in mind prevention is still better.

It's been discussed, but herein lies the problem: If the whole house GFCI was for personal protection (5 ma), and not equipment protection (typically 50 ma or more), then each circuit could adds a tiny bit to the overall, say, .25 ma ground fault leakage per circuit (which really is not much), for 20 circuits, is your 5 ma trip level.

You'd never be able to keep that main GFCI 'on', it would always be tripped.

Installing a Class B 50 ma GFCI device (for protection of equipment) would not do any good towards protecting the people in the house.

For whole house protection, you'd have to put a GFCI on each circuit.

Now, you COULD AFCI the whole house. In fact, that IS being discussed.

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Jerry Peck
South Florida

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Originally Posted By: jpeck
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Bob,


While I did not work on, or challenge, the 277 v stuff much, I also did stupid (as it now appears, then the risk did not seem that bad, that's what youth does to you) things with 120 v residential circuits.

One I remember (because it was sooooo stupid) was this: I was installing a fountain light in an outdoor fountain / reflecting pool at a large residence and had a problem, the fountain was full of water.

Let's see, now, if I use an extension bit, I could drill into the water and, as long as I kept the water out of the drill motor vents, I would probably be safe. By the way, it was a metal case drill (this was a long time ago, no GFCI protection yet). I drilled into the fountain bottom to set the lead anchors for the underwater light, and, yes, I was able to JUST keep the drill from going into the water far enough to JUST keep the water out of the motor vents.

I not only did this for one anchor, but for three anchors at each of three underwater lights - nine times. I guess I figured is I made it the first time, my risk factor was okay.

All I can say now (whenever I think of that) is DUMB! DUMB!

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Jerry Peck
South Florida

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Originally Posted By: Frank Wils
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My question is this. is it acceptable to install a GFCI on an ungrounded outlet to protect yourself when using a grounded device, for example - an older house, knob and tube wiring - replaced main service to grounded romex and breakers, but all lines in wall are still two wire - therefore all outlets are still ungrounded. Would you reccomend that the home owner install GFCI’s on these ungrounded receptacles?

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Originally Posted By: jpeck
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Frank,


Yes. Absolutely.

It will not provide a ground, but, it will provide GFCI protection.

In some cases, the GFCI protection will be better than the ground. (That ought to start some discussion as to the "why".)

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Jerry Peck
South Florida

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Originally Posted By: Bob Badger
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jpeck wrote:

[ If the whole house GFCI was for personal protection (5 ma), and not equipment protection (typically 50 ma or more), then each circuit could adds a tiny bit to the overall, say, .25 ma ground fault leakage per circuit (which really is not much), for 20 circuits, is your 5 ma trip level. You'd never be able to keep that main GFCI 'on', it would always be tripped.

I am with you Jerry, my thought was at each device or at least per circuit with 5 ma protection. 

No I would not suggest 5 ma or even 50 ma main protection, more harm then good having all the power dump for a minor fault.

I have tripped out a 2000 amp bus duct main from shorted 20 amp 277 volt lighting circuits, the GFP 2000 amp breaker had never been adjusted from the factory's fast response time, low amperage settings.

We need an engineers guidance on what levels to set these at (liability) and without that we leave them as received from the factory.


As for AFCI protection, you can count on seeing the requirements expanded.

Bob

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Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

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Originally Posted By: Bob Badger
This post was automatically imported from our archived forum.

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Frank Wils wrote:

My question is this. is it acceptable to install a GFCI on an ungrounded outlet to protect yourself when using a grounded device,

Previously my answer would have matched Jerry's on this, and it still matches as far as being acceptable to replace the old outlets with GFCIs, in fact I highly recommend it.

As for if the NEC allows you to run grounded equipment from this outlet my answer is now no.

Another code article was pointed out to me and I see no exceptions for these replacement outlets, I guess the fact a sticker is required at each of these outlets saying "No Equipment Ground" is supposed to tell the home owner not to plug in grounded equipment.

Quote:

250.114 Equipment Connected by Cord and Plug. Under any of the conditions described in (1) through (4), exposed non?current-carrying metal parts of cord-and-plug-connected equipment likely to become energized shall be grounded. Exception: Listed tools, listed appliances, and listed equipment covered in (2) through (4) shall not be required to be grounded where protected by a system of double insulation or its equivalent. Double insulated equipment shall be distinctively marked. (3)In residential occupancies: a.Refrigerators, freezers, and air conditioners b.Clothes-washing, clothes-drying, dish-washing machines; kitchen waste disposers; information technology equipment; sump pumps and electrical aquarium equipment c.Hand-held motor-operated tools, stationary and fixed motor-operated tools, light industrial motor-operated tools d.Motor-operated appliances of the following types: hedge clippers, lawn mowers, snow blowers, and wet scrubbers e.Portable handlamps

By the way information technology equipment is not just a PC, it is a whole UL category that includes paper shredders, intercoms, phone answering machines, electric pencil sharpeners and on and on. 

If anyone can find an exception to 250.114(3) I would be glad to hear about it.

My own opinion is no homeowner is going to pay a bit of attention to that list even if they knew it existed.

You are still safer to use this equipment in a non grounded GFCI than a non grounded and non GFCI circuit.

Bob

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Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

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Originally Posted By: jpeck
This post was automatically imported from our archived forum.

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Bob Badger wrote:

Previously my answer would have matched Jerry's on this, and it still matches as far as being acceptable to replace the old outlets with GFCIs, in fact I highly recommend it. As for if the NEC allows you to run grounded equipment from this outlet my answer is now no.

I'll go along with that.

I was answering whether or not to install GFCI on ungrounded two-wire systems, which is allowed. However, I also see your point in that they are not allowed to be used for grounded equipment (as stated in your post and the code).

Thus, while you can, and are urged to, replace ungrounded receptacles with GFCI protected ones, you just cannot use them for much. 

(Am I missing something or having a brain lapse here, there is no "when there is a conflict between code sections, the most restrictive shall apply"?)

That means the real answer would be 'No, do not replace ungrounded two wire receptacles with GFCI protected ones, but instead, either add a proper ground as specified and replace with grounding type receptacles or re-wire the house.

Whoa, and I thought I was tough.

Am I just having a brain dead day or is there no "the most restrictive shall apply"?

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Jerry Peck
South Florida

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Originally Posted By: Bob Badger
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I do not know if there is a general rule of the most restrictive shall apply, although to me that makes sense.


I do know there are some specific rules like that.

When two ampacitys for a conductor are determined the lesser one shall be used, or something close to that.

When 250.114 was pointed out to me I commented it makes no sense as homeowners will not be aware of it.

The response was "Who said the code has to make sense" 

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Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

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Originally Posted By: Mike Parks
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Who said the code has to make sense?


It makes perfect sense to those how understand it. 


The AHJ.   

Mike P.

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Originally Posted By: jpeck
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Bob,


All building codes that I have seen have the 'most restrictive shall apply' requirements, with the exception that specific requirements (such as manufacturers installation instructions) take precedence if there is a conflict.

The NEC, through 110.3(B) is like that as regards to listing and labeling and manufacturers instructions.

Mike,

Show me an AHJ who "understands" the NEC and I will show you one who does not have a firm grasp on reality. 

However, THEY ARE the AHJ, so whether or not it makes sense to us, if it make sense to them, we have to convince them otherwise to prevail.

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Jerry Peck
South Florida

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Originally Posted By: roconnor
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Mike Parks wrote:

It makes perfect sense to those how understand it. ... The AHJ.

IMHO this has nothing to do with the codes being clear. It makes sense to the AHJ only because the "code" is not what is written in a book ... the "code" is what the AHJ says is written in the book. THAT make perfect sense to me since I have worked as an AHJ ... 

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Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

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Originally Posted By: Bob Badger
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roconnor wrote:

I think there is something being missed here ... or maybe something that needs to be clarified about GFCI protection. A GFCI will protect you from a line to ground fault, but it will NOT provide protection if you somehow complete a circuit between the hot and neutral wires ... 

That is an excellent point, one that should be included in this thread.

While that is a rare occurrence (line to line shocks at appliances) it can happen and a GFCI will not 'know' the difference between you and a lamp.

At Mike Holt's a parent was convinced the best electrical protection for his kids was GFCI protecting all outlets, they could not get this line to line problem and they could not understand the importance of child proofing the outlets even when GFCI protected.

Myself I have 3 & 5 year old girls, the outlets in their rooms are dead and still child proofed.

Live outlets they have access to have large in use child proof devices.

I know what shocks feel like, I do not want them to know that too.

Bob

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Bob (AKA iwire)
ECN Discussion Forums
Mike Holt Code Forum

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Originally Posted By: roconnor
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Yes … a GFCI will not protect a small child (or anyone else) who for example happens to stick something metal in each slot.


Let me just say that I was VERY curious as a kid, and I learned the HARD way at an early age to have a healthy respect for electricity ... I cant for the life of me figure out how I was lucky enough to survive some of my "experiments" ... 

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Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong