Two pronged outlets

Guys;

This is getting way too involved.

A GFCI does not detect a fault to ground. It only detects a fault if the current ‘coming out’ or the hot is not matched by the current ‘going in’ to the neutral.

Inside is a coil. It checks the current flow difference between the hot an neutral. If there is an imbalance (typically 5/1000 of and an amp for more that 1/10th of a second) it will trip.

In other words, if a person grabs a metal enclosed appliance (like a good quality blender) and the hot is contacting the metal enclosure, the current will flow through the person to ground. This means that the current is not returning through the neutral (like it should) but is instead getting back to ground through the person. The ‘ground fault’ is not dependant on the receptacle being grounded but on the current flowing back “to ground” in a manner other than the neutral (which is bonded and the same as ground, with regards to allowing the current to flow as intended.

The easiest way to test this in the cheap testers is to ‘short circuit’ the hot to ground. Therefore, if there is no ground in the receptacle, the tested will not properly test. That is why testing via the test button is used because the test is a test of the mechanism by which the receptacle operates, rather than just a simple (and cheap) short circuit.

Hope this helps

Uh, yeah…
Like I said:

Check out a little article I wrote:

http://deckerhomeservices.com/gfci_and_afci_explained.htm

And to answer ‘Speedy’, what is ‘legal’ is not always the safest.

Would a house built in the 70’s and without GFCI protection, ‘safer’ if the owner installed GFCI receptacles or GFCI breakers to the branch circuits serving areas where there is direct contact with ground or water?

Think like a home inspectors (ie, the safety of the client), not like an electrician (ie, local AHJ ‘code’).

If someone dies, the electrician can say the work was in compliance with locak AHJ code and have no liability.

If someone dies and the home inspector says, “Hey, it was ‘code’.”, there goes your E & O premiums.

HIs have a much higher standards than mere local ‘code’. Many lawsuits have born this out.

Something to seriously think about.

IMO legal is safe, otherwise why have codes?
Safest” is a subjective term. If I wire to code, and beyond, it IS absolutely safe. An ungrounded GFI device IS safer than an ungrounded regular receptacle. A grounded circuit with a GFI is “safest”? I guess so, yes.
I was merely referring to the fact that the replacement of an ungrounded recepetacle with a GFI device IS legal. Nothing more.

I do consider my customer’s safety AND the local code. IMO both go hand in hand and there is very little difference between the two.

When I do a service change do I go around the house pointing out every little thing that is not up to current code? Absolutely not.
Do I point out anything I see that may be dangerous or in dire need of an upgrade? Absoultely.

Clear?

And heres some more confusion: While 406.3(D)
permits us to install a GFCI in place of a two prong receptacle, 250-114 does not allow us to plug anything with a grounding pin into it!

So our testers won’t trip them but a wet hand will? Correct?

Only if you are grounded. . .

May be very involved by in my opinion ALL HI’s should know how they work and the understanding of it…for retained knowledge…not to quote to clients…once a person stops feeling like they need to learn…they should LEAVE the profession they are in…:slight_smile:

What about Brians note on 250?

Hope this helps. It’s from an OSHA site.

The short version is-

If a GFCI is used to replace a 2-wire outlet it must me marked “No Equipment Ground” and any receptacles protected by and after the GFCI must be marked “GFCI Protected” and “No Equipment Ground”

however-

GFCI protection is not a substitute for equipment requiring grounding.


The equipment grounding requirements for cord and plug connected equipment, contained in Section 250-114 of the 1999 NEC, does not provide an exception that permits the use of a GFCI in lieu of equipment grounding. The GFCI provisions, contained in Section 210-7(d), pertain to the requirements for receptacle replacement and not to the grounding of equipment. (2)](http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=22962#2FOOTNOTE) The use of a GFCI-type receptacle or GFCI-type circuit breaker in lieu of an equipment grounding conductor run to the receptacle outlet is permitted by the 1999 NEC, Section 210-7, on branch circuits. However, all of the listed conditions must be met to meet this code exception. Section 210-7(d)(3) contains additional marking and wiring requirements that must be met when GFCI-type receptacle(s) or circuit breaker(s) are used when a grounding means is not available. Strict compliance with these NEC requirements would constitute a de minimis violation of OSHA electrical standard §1910.304(a)(3) as the GFCI-type receptacles would provide additional personnel protection and would not be used in lieu of equipment grounding.
For example, if a GFCI-type receptacle is used, it must be visibly marked “No Equipment Ground,” and equipment required to be grounded may not be used in the ungrounded, GFCI-type receptacle. However, many appliances (i.e., lamps; toasters; televisions; double insulated appliances) and tools (i.e., double insulated tools; tools supplied with a low voltage isolating transformer) are not required to be grounded and they may be used in an ungrounded, GFCI-type receptacle. The GFCI feature of these GFCI-type receptacles provides additional electrocution protection in the event of misuse (i.e., a floor buffing machine is powered by a 3-prong plug from a properly marked and wired ungrounded, GFCI-type receptacle).