I am trying to sort out this GFCI thing. 406.3(D)(3)(b) states that a GFCI can be installed without an equipment ground. Isn't this intented to have the GFCI's placed in bathrooms and kitchens that are two wire? I do not believe that it is to justify installing GFCI's thoughout a house to be able to use equipment that has a ground conductor. Wouldn't that be just as bad as using a 3 to 2 ground plug adapter? I do not believe that allowing that benefits anyone, or am I wrong?
GFCI on two wire systems
- Thread starter MJGero
- Start date
- Status
Twoskinsoneman
Senior Member
- Location
- West Virginia, USA NEC: 2020
- Occupation
- Facility Senior Electrician
406.3(D)(3) Non–Grounding-Type Receptacles. Where attachment
to an equipment grounding conductor does not exist
in the receptacle enclosure, the installation shall comply
with (D)(3)(a), (D)(3)(b), or (D)(3)(c).
(a) A non–grounding-type receptacle(s) shall be permitted
to be replaced with another non–grounding-type receptacle(
s).
(b) A non–grounding-type receptacle(s) shall be permitted
to be replaced with a ground-fault circuit interruptertype
of receptacle(s). These receptacles shall be marked
“No Equipment Ground.” An equipment grounding conductor
shall not be connected from the ground-fault circuitinterrupter-
type receptacle to any outlet supplied from the
ground-fault circuit-interrupter receptacle.
(c) A non–grounding-type receptacle(s) shall be permitted
to be replaced with a grounding-type receptacle(s)
where supplied through a ground-fault circuit interrupter.
Grounding-type receptacles supplied through the groundfault
circuit interrupter shall be marked “GFCI Protected”
and “No Equipment Ground.” An equipment grounding
conductor shall not be connected between the groundingtype
receptacles.
Sorry cut that off short before I finished. My intent wasn't to just copy code over. I believe the intent is exactly that to allow you to put the three prong receptacles in. Where ever you want. Where is the hazard if GFCI is provided? We can't make people re-wire their entire old house because they want to use three prong appliances. If you have the GFCI it is a LOT safe than the adapter. Let's face it people are GOING to use their stuff. This is the perfect way (requirement) to allow then reasonable easy to make it safe.
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A wiring system with a ground is safer than one without it. But short of rewiring all those millions of miles of 2-wire circuits still in use, we're allowed to use GFIs instead.
Not a perfect solution, but one with the idea that installing a GFI at least provides more protection (given GFIs safety record) than doing nothing.
Not a perfect solution, but one with the idea that installing a GFI at least provides more protection (given GFIs safety record) than doing nothing.
electricalperson
Senior Member
- Location
- massachusetts
a gfci doesnt need an equipment ground to work it senses an unbalance between L and N and trips. current doesnt have to go through the EGC it can go through your body to a concrete floor and trip the gfci
a gfci will give better protection from shock than a 2 wire ungrounded receptacle.
a gfci will give better protection from shock than a 2 wire ungrounded receptacle.
Well, it won't eleminate a shock, but will limit the time one can occur. That's what GFIs are designed to do.
406.3(a) .
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
090415-2047 EST
A GFCI does not prevent a shock, but in most cases it should prevent a lethal shock. An EGC does not prevent a shock. If you contact a hot wire and something at a considerably different potential you should get a shock and it may be lethal.
Where an EGC is useful is if you have an internal short in some equipment with a conductive exterior that is connected to an EGC, then you may trip the circuit's breaker. If the short is a very low resistance then the equipment case may rise to 1/2 the supply voltage for a short time until the breaker trips. If the short is a high resistance the breaker may not trip. but depending upon the short current magnitude may cause the equipment enclosure to rise some voltage above other items, such as a water pipe.
Suppose the EGC resistance back to the main panel is 0.25 ohms and the short current is 20 A, then the EGC at the equipment will rise to 5 V above a close by water pipe.
.
A GFCI does not prevent a shock, but in most cases it should prevent a lethal shock. An EGC does not prevent a shock. If you contact a hot wire and something at a considerably different potential you should get a shock and it may be lethal.
Where an EGC is useful is if you have an internal short in some equipment with a conductive exterior that is connected to an EGC, then you may trip the circuit's breaker. If the short is a very low resistance then the equipment case may rise to 1/2 the supply voltage for a short time until the breaker trips. If the short is a high resistance the breaker may not trip. but depending upon the short current magnitude may cause the equipment enclosure to rise some voltage above other items, such as a water pipe.
Suppose the EGC resistance back to the main panel is 0.25 ohms and the short current is 20 A, then the EGC at the equipment will rise to 5 V above a close by water pipe.
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little george
Member
Check out 250.114 for equipment that needs to be grounded and can not be plugged into a non-grounded circuit. Or should I say a circuit without an equipment grounding conductor.
Fulthrotl
~Autocorrect is My Worst Enema.~
- Occupation
- E
no. if you get between line and neutral, you are a resistive load, and will
be treated as such, unless you pull so much current you trip the breaker.
if you get between a hot, and something not a neutral, the GFCI will sense
electrons sneaking out and not coming back, and will shut off the tap.
normal shutoff time 7 or 8 milliseconds. normal shutoff current, 60 milliamps.
between hot and neutral, however, consider yourself a toaster oven.
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Quote:
Originally Posted by mjgero
is there a place in the code to require a properly grounded receptacle for equipment with an equipment ground?
406.3(a)
given this code section, and 406.3(B) any equipment that has an EGC shall be connected to a EGC though a receptacle. but doesn't 406.3(D) allow a GFCI to be installed without the EGC?
Originally Posted by mjgero
is there a place in the code to require a properly grounded receptacle for equipment with an equipment ground?
406.3(a)
given this code section, and 406.3(B) any equipment that has an EGC shall be connected to a EGC though a receptacle. but doesn't 406.3(D) allow a GFCI to be installed without the EGC?
250.114(a)&(b) has appliances, computers, aquiriums, being required to be connected to a EGC and therefore a properly grounded receptacle would be required even though the current system is a two wire. the GFCI eception would not apply.
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406.3(D) specifically addresses existing situations where the original wiring was installed without a grounding conductor.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
If you look at what I highlighted in red, it clearly covers the requirements of 250.114
- Location
- Massachusetts
No it does not do any such thing, 250.114 does not have anything at all to do with the grounding requirements of receptacles.
250.114 provides grounding requirements for cord and plug connected utilization equipment and basically if the equipment has a grounding type cord it is required to be supplied with a grounding means.
The fact that a GFCI may be in place due to 406.3(D) has no impact on the requirements of 250.114.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
I'm not saying your wrong on this, but to me if this were true then there would never be a reason to use any of the methods that 406.3 allows us to put a 3 prong receptacle in on a two wire circuit, as most cord and plug loads in a home are only two prong anyways, so why ever change it to a 3 prong?
Wasn't these allowments put in the code to stop people from cutting off the ground prong in the first place.
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No equipment ground sticker on three prong outlets
No equipment ground sticker on three prong outlets
I think you should only put two prong outlets when there's no EGC. Not even GFCI outlets, because those stickers fall off over time and three prong cord and plug equipment are plugged in that are supposed to be grounded and the person has no idea that there's no ground.
No equipment ground sticker on three prong outlets
I think you should only put two prong outlets when there's no EGC. Not even GFCI outlets, because those stickers fall off over time and three prong cord and plug equipment are plugged in that are supposed to be grounded and the person has no idea that there's no ground.
paul
Senior Member
- Location
- Snohomish, WA
Yes, there is no ground. However there is GFCI protection. Where is the hazard if the sticker falls off?
scubahigh97
Member
has anyone tried to trip a nongrounded gfci with a gfci checker. the one where you plug it in and push the little button. it wont trip, some one told me l-n inbalance was the old ones. now they check ground faults
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