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#1
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Ungrounded GFCI with ground jumpered to neutral
When installing GFCI outlets on ungrounded circuits today, the
electrician fitted each with a jumper between ground and neutral. I told him I'd thought I'd read that this was a bad thing but he insisted that it was the correct way to wire an ungrounded GFCI, that he does this all the time, and that if I doubted him, to ask the city inspector. He did not label the GFCI outlets as "no equipment ground", which also seems like a no-no. Am I right that this is bad? Is it bad only in the case of a miswired circuit? I can find one or two web sites that say it is bad but "someone said so on a web page" does not make a persuasive argument, and if it is unsafe, I'd rather have it fixed than wait and raise it with the inspector. Can anyone point to an authoritative description of why this is bad? I can see it is a problem for a miswired circuit with hot and neutral swapped. Are there other scenarios where it is dangerous or might increase reliance on the GFCI tripping correctly? Based on my limited understanding of GFCI operation, with the jumper, if an appliance case were to become energized, current would immediately flow through the ground terminal, through the jumper to the neutral return, bypassing the GFCI transformer and tripping the GFCI. Without the jumper, energizing the case wouldn't produce a current until (say) my body creates an alternate path to ground. The first scenario actually seems marginally better? -- Dave |
#2
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Ungrounded GFCI with ground jumpered to neutral
It's improper to do, but the only ill affect I can see would be if any of
the outlets "actually" became grounded. wrote in message ups.com... When installing GFCI outlets on ungrounded circuits today, the electrician fitted each with a jumper between ground and neutral. I told him I'd thought I'd read that this was a bad thing but he insisted that it was the correct way to wire an ungrounded GFCI, that he does this all the time, and that if I doubted him, to ask the city inspector. He did not label the GFCI outlets as "no equipment ground", which also seems like a no-no. Am I right that this is bad? Is it bad only in the case of a miswired circuit? I can find one or two web sites that say it is bad but "someone said so on a web page" does not make a persuasive argument, and if it is unsafe, I'd rather have it fixed than wait and raise it with the inspector. Can anyone point to an authoritative description of why this is bad? I can see it is a problem for a miswired circuit with hot and neutral swapped. Are there other scenarios where it is dangerous or might increase reliance on the GFCI tripping correctly? Based on my limited understanding of GFCI operation, with the jumper, if an appliance case were to become energized, current would immediately flow through the ground terminal, through the jumper to the neutral return, bypassing the GFCI transformer and tripping the GFCI. Without the jumper, energizing the case wouldn't produce a current until (say) my body creates an alternate path to ground. The first scenario actually seems marginally better? -- Dave |
#3
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Ungrounded GFCI with ground jumpered to neutral
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#4
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Ungrounded GFCI with ground jumpered to neutral
Pop` wrote:
Neutral and Ground are NEVER to meet except back at the breaker panel! I'd also have to report him to the BBB if it happened to me, and possibly the licensing board if he got snotty about it. In particular, the inspector should be alerted to the situation when he comes. You WILL be getting an inspection, right? From the sound of it, it might be important for you to have one in case you were trying to skip out of it. I understand that in a grounded system, having multiple links between ground and neutral is a big no-no. But in this ungrounded scenario the right thing is less obvious to me. We do intend to get the inspection. But calling the city first sounds like a good idea. -- Dave |
#5
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Ungrounded GFCI with ground jumpered to neutral
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#6
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Ungrounded GFCI with ground jumpered to neutral
Assuming the GFCI's never "wear out" and cease performing as they should, I can't think of a scenario in which connecting the ground to neutral would vreate a hazard. But it could create bothersome tripping of the GFCI because modern ones will sense nuetral to ground leakage. So, say you have a three wire corded device plugged into one of those outlets with the metal case of the device connected to the ground pin of the plug. If a leakage is created between that device's case and ground, the GFCI will trip, which wouldn't happen if the guy hadn't wired the ground to neutral. I suspect that the electrician wired the neutral on the LINE side to the grounding screw. It would not trip because the LOAD side neutral would not have a path to ground. I suspect the electrician got burned by an inspected when he put in a GFCI on an un-grounded outlet. (Lots of folks don't understand how this can be OK.) The the LINE side neutral tied to the ground screw the outlet would "Look" like a normally grounded GFCI circuit for most purposes. Any reasonable electrical tests would not be able to distinuish this ungrounded circuit from a properly grounded circuit. The only hazard I can envision is if the GFCI were to become inoperative and also the neutral wire feeding the GFCI were to open. Then, the case of a three wire corded device could rise to line voltage through the resistance of whatever load is inside the device, admittedly a long shot, but overall, I still think your guy shouldn't have connected the ground to neutral, and installed those "ungrounded" labels. Well, just lifting the LINE side neutral while the power is off can create a very dangerous situation when the power comes back on. And you are right that with this arrangement a lifted neutral would be bad news. A lifted neutral presents a much bigger safety risk than a lifted ground. I can't recall seeing a GFCI receptical without ground pin holes, but maybe they are made for installations such as yours, so there's no misleading "ground" pin hole on the receptical. If you read the directions when you use them on ungrounded circuits you are supposed to apply a lable that says "ungrounded." |
#7
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Ungrounded GFCI with ground jumpered to neutral
John Gilmer wrote:
Assuming the GFCI's never "wear out" and cease performing as they should, I can't think of a scenario in which connecting the ground to neutral would vreate a hazard. But it could create bothersome tripping of the GFCI because modern ones will sense nuetral to ground leakage. So, say you have a three wire corded device plugged into one of those outlets with the metal case of the device connected to the ground pin of the plug. If a leakage is created between that device's case and ground, the GFCI will trip, which wouldn't happen if the guy hadn't wired the ground to neutral. I suspect that the electrician wired the neutral on the LINE side to the grounding screw. It would not trip because the LOAD side neutral would not have a path to ground. You got me there, John. I was focused on the "load side" and didn't think about it being wired to the "line side". I suspect the electrician got burned by an inspected when he put in a GFCI on an un-grounded outlet. (Lots of folks don't understand how this can be OK.) The the LINE side neutral tied to the ground screw the outlet would "Look" like a normally grounded GFCI circuit for most purposes. Any reasonable electrical tests would not be able to distinuish this ungrounded circuit from a properly grounded circuit. The only hazard I can envision is if the GFCI were to become inoperative and also the neutral wire feeding the GFCI were to open. Then, the case of a three wire corded device could rise to line voltage through the resistance of whatever load is inside the device, admittedly a long shot, but overall, I still think your guy shouldn't have connected the ground to neutral, and installed those "ungrounded" labels. Well, just lifting the LINE side neutral while the power is off can create a very dangerous situation when the power comes back on. And you are right that with this arrangement a lifted neutral would be bad news. A lifted neutral presents a much bigger safety risk than a lifted ground. I can't recall seeing a GFCI receptical without ground pin holes, but maybe they are made for installations such as yours, so there's no misleading "ground" pin hole on the receptical. If you read the directions when you use them on ungrounded circuits you are supposed to apply a lable that says "ungrounded." That I know, but those labels can't be guaranteed to to get left stuck in place forever. But, now that I think about it while I'm keying this in, a "two pin" receptical might encourage someone to use a "2 to 3" adaptor and connect its ground lead to the cover plate retaining screw, with the mistaken assumption that it would provide the ground. Sometimes you just can't idiot proof stuff enough, huh? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) The speed of light is 1.8*10^12 furlongs per fortnight. |
#8
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Ungrounded GFCI with ground jumpered to neutral
On 2006-12-16, John Gilmer wrote:
I suspect that the electrician wired the neutral on the LINE side to the grounding screw. It would not trip because the LOAD side neutral would not have a path to ground. I'm sorry, isn't this backwards? I assume the terminology is LINE side = incoming power and LOAD side = receptacle. If the receptacle's ground plug is connected to the LINE side neutral, then the GFCI will trip with a ground fault: the current goes through the LOAD hot but not through the LOAD neutral, returning instead through the LINE neutral via the EGC. This current imbalance will trip the GFCI. If the receptacle's ground plug is connected to the LOAD side neutral, then the GFCI will not trip with a ground fault, as the current does return via the LOAD side neutral. Cheers, Wayne |
#9
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Ungrounded GFCI with ground jumpered to neutral
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#10
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Ungrounded GFCI with ground jumpered to neutral
UL changed the standard, and for "new" GFCIs I believe that if the neutral is open the receptacle is disconnected from the line. Nope! The GFCI needs power to operator it's sensing circuitry. Without a neutral it doesn't have any power and it will not trip. Anyone tested either? Yes, I have. I have a cord set salvaged from an old lamp or some such. I put female "spade" connectors on the wire end. If you take a little solid wire and put it the back of the "line" side of the GFCI, you can run all kinds of experiments in RELATIVE safety. Don't get me wrong, you will have bare HOT terminals so you might consider powering your experiment from a GFCI protected circuit. AND BE CAREFUL. (I have been doing stupid stuff like this since I was about 7 years old butt I certainly would not permit my kid to do it.) Basically, if you reset the GFCI with power on, turn power off, disconnect neutral from GFCI, and put power back on you can draw all the power you want between GFCI load side HOT and GROUND or another neutral. There just will not be any power going into the sensing circuit of the GFCI. And that's why, children, losing a neutral is as dangerous or MORE dangrous than losing a GROUND. -- bud-- |
#11
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Ungrounded GFCI with ground jumpered to neutral
John Gilmer wrote:
UL changed the standard, and for "new" GFCIs I believe that if the neutral is open the receptacle is disconnected from the line. Nope! The GFCI needs power to operator it's sensing circuitry. Without a neutral it doesn't have any power and it will not trip. Anyone tested either? Yes, I have. You threatened to test this in a previous thread. Thanks for posting. I have a cord set salvaged from an old lamp or some such. I put female "spade" connectors on the wire end. If you take a little solid wire and put it the back of the "line" side of the GFCI, you can run all kinds of experiments in RELATIVE safety. Don't get me wrong, you will have bare HOT terminals so you might consider powering your experiment from a GFCI protected circuit. AND BE CAREFUL. (I have been doing stupid stuff like this since I was about 7 years old butt I certainly would not permit my kid to do it.) (I have a cord set with insulated aligator clips at the end and am fairly paranoid when using it.) Basically, if you reset the GFCI with power on, turn power off, disconnect neutral from GFCI, and put power back on you can draw all the power you want between GFCI load side HOT and GROUND or another neutral. There just will not be any power going into the sensing circuit of the GFCI. Was this a "new" UL standard GFCI or an "old" one? When reverse powered to the "load" teminals (GFCI not initally tripped), the receptacle will be live for an "old" one (not required, but that is how they were made) and dead for a "new" one. My guess is that the "old" GFCIs use a mechanically held, electrically tripped relay that operates as you describe. My guess is that a "new" GFCI has normally open relay contacts that connect "line", "load" and receptacle together only when powered. If that is true, a "new" GFCI would not connect "line" to the receptacle with no neutral. One change in the "new" UL standard is that reverse line-load wiring will not power the receptacle or "line" terminals. I believe that requires a relay that does not close unless powered from the "line" side. Another change in the "new" UL standard is that the GFCI be more likely to fail safe. "Old" GFCIs had a habit of failing with the "line" connected to the receptacle and "load", and not tripping anymore. That is one reason I think "old" GFCIs have mechanically held contacts. And my guess is that "new" GFCIs require the relay to be powered to energize either the receptacle or "load" terminals. ------ Has anyone who has investigated a GFCI with a hammer looked at how the "old" or "new" relays work? -- bud-- |
#13
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Ungrounded GFCI with ground jumpered to neutral
wrote in message oups.com... So, just to follow up, I talked to the city electrical inspector. She confirmed that connecting the neutral and ground pins of a GFCI was not code compliant (as expected). But she said that it should not create a safety issue, and since retrofitting GFCI outlets doesn't require a permit and code check, she didn't see any reason to do anything about it. -- Dave Without a separate ground the GFCI will NOT function properly and so it IS a safety hazard. You have a lousy inspector. wrote: Pop` wrote: Neutral and Ground are NEVER to meet except back at the breaker panel! I'd also have to report him to the BBB if it happened to me, and possibly the licensing board if he got snotty about it. In particular, the inspector should be alerted to the situation when he comes. You WILL be getting an inspection, right? From the sound of it, it might be important for you to have one in case you were trying to skip out of it. I understand that in a grounded system, having multiple links between ground and neutral is a big no-no. But in this ungrounded scenario the right thing is less obvious to me. We do intend to get the inspection. But calling the city first sounds like a good idea. -- Dave |
#14
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Ungrounded GFCI with ground jumpered to neutral
She confirmed that connecting the neutral and ground pins of a GFCI was not code compliant (as expected). But she said that it should not create a safety issue, and since retrofitting GFCI outlets doesn't require a permit and code check, she didn't see any reason to do anything about it. -- Dave Without a separate ground the GFCI will NOT function properly and so it IS a safety hazard. You have a lousy inspector. GFCI's will work with no ground. I'm not sure what happens in that wiring arrangement if the nuetral fails between the GFCI and the service panel, though, while you have a grounded appliance plugged in. |
#15
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Ungrounded GFCI with ground jumpered to neutral
Mike Dobony wrote:
wrote in message oups.com... So, just to follow up, I talked to the city electrical inspector. She confirmed that connecting the neutral and ground pins of a GFCI was not code compliant (as expected). But she said that it should not create a safety issue, and since retrofitting GFCI outlets doesn't require a permit and code check, she didn't see any reason to do anything about it. -- Dave Without a separate ground the GFCI will NOT function properly and so it IS a safety hazard. You have a lousy inspector. Without a ground a GFCI WILL function. They work fine on wiring without a ground and are permitted by the NEC as replacements for ungrounded outlets (with a "No equipment ground" label). As John Gilmer has pointed out a couple times, if the supply neutral opens the wiring is a hazard. Example, you plug in a metal case drill that is equipped with a "ground" wire. The supply neutral to the GFCI opens. You pull the trigger in the drill. The hot connects through the drill motor to the neutral. The neutral is open so it is now at 120V to earth (everywhere downstream from the neutral break). The "ground" is connected to the neutral at the receptacle so the receptacle "ground" and the metal case of the drill are at 120V to earth. The GFCI is not powered so it doesn't work. Sounds like a "safety issue" to me. If there is an open neutral, turning on a light on one miswired outlet will make the "grounds" hot on all the other miswired outlets downstream from the neutral break. You have a lousy inspector. -- bud-- |
#16
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Ungrounded GFCI with ground jumpered to neutral
I'm not an expert on electrical wiring, but it seems to me that the
dangerous part is having a gfci where there is no ground - you would assume it';s safer than it is. You wouldn't want an ungrounded outlet there, would you? - the gfci will work the same way, for all intents and purposes. shelly |
#17
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Ungrounded GFCI with ground jumpered to neutral
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#18
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Ungrounded GFCI with ground jumpered to neutral
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#19
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Ungrounded GFCI with ground jumpered to neutral
wrote:
wrote: I'm not an expert on electrical wiring, but it seems to me that the dangerous part is having a gfci where there is no ground - you would assume it';s safer than it is. You wouldn't want an ungrounded outlet there, would you? - the gfci will work the same way, for all intents and purposes. It will still detect current going through your body to ground. With a ground wire the current _may_ go through the ground wire instead. I believe code allows an ungrounded outlet to be replaced with a gfci. Correct The last gfci I bought came with "no equipment ground" stickers. I assume these stickers are placed on an ungrounded gfci to alert the user that there is no ground. Also correct. Grounded or not, it seems a gfci will trip anytime there is an interruption to current flow. A GFCI will trip when the current in the hot and neutral are different by 5mA (0.005A). If the current is different it is going somewhere - possibly through your body to ground. -- bud-- |
#20
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Ungrounded GFCI with ground jumpered to neutral
A GFCI will trip when the current in the hot and neutral are different by 5mA (0.005A). If the current is different it is going somewhere - possibly through your body to ground. It can only trip if its internal electronics is powered up. If you lose neutral when the power is off, the electronics will not be powered with the power comes back on. Then you could draw AMPS from the HOT wire to ground and the GFCI will not react. -- bud-- |
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