Non Grounded duplex poll. Which is safer?

[frankft2000]

The GFCI will start to react anytime the current imbalance gets above around 6ma. The time between that and when the GFCI opens you are getting full voltage and current limited only by your skins resistance.

The GFCI cannot limit current or voltage, all it can do is open the circuit.

OK, but how long would that take, and would a circuit breaker with equipment ground open faster?

 

[480sparky]

OK, but how long would that take, and would a circuit breaker with equipment ground open faster?

If you had enough current going through you to operate the OCD, you're dead.

 

[don_resqcapt19]

A local city informed me that they do not recognize replacing a non grounded receptacle with GFCI protection. ...

They may be looking at 250.114. There are a number of items that always require an EGC and the GFCI does not take the place of the EGC.

 

[kwired]

Nice discussion here. I did not think a person whould get, or feel a shock of 120 volts if the GFCI was working properly. My line of thinking was that a proper working gfci would trip at .5 milliamps as to prevent death, where on this board I have read several times about circuit breakers not tripping, even with direct shorts, and I'm not talking just about fedaral pacific breakers.

If you want to find out try testing a GFCI with one of those plug in bug-eye testers where there is no equipment ground and you have a metal weatherproof cover that is touching your hand as you press the test button on the tester and you are in contact with the ground or other grounded object at the same time.

I have not done this but have heard of someone that was not thinking one time. Actually an inspector, plugged in his tester - outdoor recepeptacle, metal cover, tester said no equipment ground. Out of habit decided to push test button to see if GFCI tripped - not thinking about the fact that the test current with no equipment ground will go out on anything connected to the EGC terminal of the receptacle which also would include the receptacle cover. He says the test current of the device is definately something you will feel. And it still was not at high enough level to actually trip the GFCI and was still felt real well.

 

[don_resqcapt19]

OK, but how long would that take, and would a circuit breaker with equipment ground open faster?

The circuit breaker with the EGC may take longer to open the circuit than a GFCI, but in many cases the EGC will completely prevent the shock while with the GFCI you have to get the shock before the device opens the circuit.

 

[LarryFine]

... with the GFCI you have to get the shock before the device opens the circuit.

True, but the GFCI effectively assures deenergization if the hazardous shock occurs, while the EGC does not.

Of course, neither prevents line-to-line shocks.

 

[Cavie]

A local city informed me that they do not recognize replacing a non grounded receptacle with GFCI protection. That got me thinking about safety.

Did you happen to ask if this was a written code amendment or just someone's "that's the way I want it." I find a lot of amendments in places that are not amendments at all. Just some inspectors wish list. Amendments must be written and adopted by the town council or who ever is in charge and be availible to the public.

 

[iwire]

True, but the GFCI effectively assures deenergization if the hazardous shock occurs, while the EGC does not.

Check out the example in post 14.

 

[M4gery]

Check out the example in post 14.

That's one example, but there are many others. Just one: think about an appliance with a frayed cord, the EGC will most likely do nothing in the case of someone touching the bare conductor while the GFCI protection will be paramount.

If all the possible examples are accounted for, which method is most likely to save more lives?

 

[frankft2000]

If all the possible examples are accounted for, which method is most likely to save more lives?

Well thats the question right there. I have learned a lot from this poll.

 

[LarryFine]

Check out the example in post 14.

That example still requires (and presumes) a 3-wire supply with an intact grounding pathway, and that the exposure includes a line-to-case fault contact.

The GFCI reacts if a shock occurs, period. Not all shocks are received from a what-should-normally-be-relied-upon-to-be-a-grounded-surface contact.

 

[iwire]

That example still requires (and presumes) a 3-wire supply with an intact grounding pathway, and that the exposure includes a line-to-case fault contact.

Which 99.999999% of supplies in the US would be.

The GFCI reacts if a shock occurs, period.

Not when it is broken:grin:, but yes normally it reacts when a shock is already happening.

Not all shocks are received from a what-should-normally-be-relied-upon-to-be-a-grounded-surface contact.

No doubt.

 

[jxofaltrds]

Bob

I am not going to try to find it, and doubt if I could, but I could swear that in one post ( a while back ) you used Mike Holts opinion that a GFCI was safer.

 

[LarryFine]

Which 99.999999% of supplies in the US would be.

Yes, but I meant that the load's cord would also have to be 3-wire; many aren't. Plus, 2-wire extension cords are often used for 3-wire loads, grounding pins are sometimes broken off, etc.

The point is that the GFCI requires little in the way of proper and intact wiring to, let's say, prevent serious death, while the EGC, which I still agree is paramount, depends on the system.

 

[GUNNING]

beat that dead horse one more time

beat that dead horse one more time

I did reread the pole. It says 2 wire GFCI vs 3 wire receptacle. Nothing broken or miss wired. Gfci's cant work and be miss wired. Grounded 3 wire can shock you up to the rated amperage or more. GFCI's will at least cut off at 5 ma going to ground which is a distinct advantage. If both of them are TR they are equally safe because plugging something into them takes a mechanical genius.

 

[drive1968]

Neither is safer. The correct answer is a two wire AFCI receptacle.

 

[iwire]

Bob

I am not going to try to find it, and doubt if I could, but I could swear that in one post ( a while back ) you used Mike Holts opinion that a GFCI was safer.

Very possible, I have been known to change my mind.

 

[don_resqcapt19]

... Grounded 3 wire can shock you up to the rated amperage or more. GFCI's will at least cut off at 5 ma going to ground which is a distinct advantage. ...

The amount of current that shocks you is the same for both systems. The GFCI does nothing to limit the amount of current that flows through your body. That is strictly a function of the voltage and the impedance of the current path. What the GFCI does is limit the time the current flows through you.

 

[jumper]

Here is what MH said about the subject at one time:

GFCI - Receptacles Without A Ground (12-30-99)

 

[George Stolz]

Thanks, Jumper.

WARNING: According to a study (based on data accumulated by the American Society of Home Inspectors) published in the November/December, 1999 issue of the IAEI News, out of 1,583 GFCI circuit breakers tested, 21% had failed. Out of 4,585 GFCI receptacles tested, 19% had failed. The failures were primarily attributed to damage from short circuits and voltage surges (lightning and other transients) to the metal oxide varistors (MOV) that are used for built-in surge suppression. In areas of high lighting activity such as Southwest Florida, the failure rate for GFCI circuit breakers was over 57%!