NEUTRAL AT SEVERICE CONDUCTORS
- Thread starter domnic
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
If the pool is 120V and fed from a gfci then I would think the gfci might get fired if you loose a neutral. We just had a job where the power company lost a neutral. I had 218v on one phase and 26V on the other. I heard the afci buzz and smoke but it did not burn it out as far as I can tell. Replaced it anyway for safety.
So if the gfci did not fry then it is possible you would fry the pump. I don't think the gfci would have an issue with it if it can handle the voltage.
So if the gfci did not fry then it is possible you would fry the pump. I don't think the gfci would have an issue with it if it can handle the voltage.
- Location
- Illinois
- Occupation
- retired electrician
If you lose the service grounded conductor, you will energize the pool bonding grid, if there is a connection to the EGC. In most cases there will be at the pool pump. There will be a serious hazard between the anything that is connected to the pool grounding grid and the earth. This same hazard will also exist between anything connected to the electrical grounding system and earth.
Short of some sort of open neutral protection that will open the ungrounded conductors if the neutral is lost, I don't know of anything that could provide protection from this problem.
Short of some sort of open neutral protection that will open the ungrounded conductors if the neutral is lost, I don't know of anything that could provide protection from this problem.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
+1
Since by losing the service neutral you have lost both the copper bond of the EGC and the neutral grounded conductor, the only return current path will be through the ground electrode system. That will not trip a protective breaker anywhere and will probably (although not guaranteed) not generate enough of a line-neutral current imbalance to trip any GFCI.
Although the entire pool grid would be raised above earth ground, it would still serve as an equipotential grid and would prevent any touch or step hazards in and around the pool all the way up to the point that you step off the pool deck. At that point one can only hope that you are stepping quickly and fall in the right direction.
Don't think that it would trip the G.F.C.I..
Curious about Don's comment about the hazard at the pool with an open grounded conductor at the service. I thought that was the reason for bonding everything that pertained to the pool including the pump motor to keep everything at the same touch potential.
I can't say that it wouldn't be hazardous. I am just curious if the equipotential bonding grid would make a difference? I am not talking about the g.f.c.i. but the shock hazard if everything is properly bonded.
After looking at GoldDiggers reply. I kind of agree with him.
Curious about Don's comment about the hazard at the pool with an open grounded conductor at the service. I thought that was the reason for bonding everything that pertained to the pool including the pump motor to keep everything at the same touch potential.
I can't say that it wouldn't be hazardous. I am just curious if the equipotential bonding grid would make a difference? I am not talking about the g.f.c.i. but the shock hazard if everything is properly bonded.
After looking at GoldDiggers reply. I kind of agree with him.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
See my post above. (Ships that pass in the night....)
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
But depending on the amount of connected unbalanced load at the time and the ground electrode system resistance, a hazardous offset of the EGC from ground will not be easily distinguishable from a supply voltage dip.
- Location
- Illinois
- Occupation
- retired electrician
That would assume that the equipotential grid was correctly installed, and there is still a lot of debate as the the effectiveness of the single bonding wire that the code permits to be used for the perimeter surface.+1
Since by losing the service neutral you have lost both the copper bond of the EGC and the neutral grounded conductor, the only return current path will be through the ground electrode system. That will not trip a protective breaker anywhere and will probably (although not guaranteed) not generate enough of a line-neutral current imbalance to trip any GFCI.
Although the entire pool grid would be raised above earth ground, it would still serve as an equipotential grid and would prevent any touch or step hazards in and around the pool all the way up to the point that you step off the pool deck. At that point one can only hope that you are stepping quickly and fall in the right direction.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
A very good point, especially for a situation like the one described where a high current is flowing through the EGC and the earth surrounding the electrodes.
If the pool deck is, in effect, a Ufer/CEE, then it can have a very low resistance to earth ground and the single bonding wire could be carrying enough current to cause a dangerous potential difference between the deck and other parts of the grid.
Volta
Senior Member
- Location
- Columbus, Ohio
Per the last couple of code cycles it's supposed to be.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Around here if you lost the neutral at the weatherhead you probably wouldn't even know it. Houses that are connected by a metal city water piping system would just send the neutral current through the water pipe to the neighbors house and back to the POCO transformer. I would guess that the GFCI would still function.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
130817-0919 EDT
A GFCI only measures the difference in current between the hot and common (neutral) lines at the output side of the GFCI. There is no connection of the GFCI common to the EGC terminal of the GFCI. It does not matter if common is 2000 V above ground or not.
An excessive voltage between hot and common at the GFCI input could damage the electronic circuitry. A low voltage between hot and common could make the GFCI inoperative.
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A GFCI only measures the difference in current between the hot and common (neutral) lines at the output side of the GFCI. There is no connection of the GFCI common to the EGC terminal of the GFCI. It does not matter if common is 2000 V above ground or not.
An excessive voltage between hot and common at the GFCI input could damage the electronic circuitry. A low voltage between hot and common could make the GFCI inoperative.
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kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
It will not trip the GFCI, there is no current imbalance on the load side. Voltage imbalance - very likely but it does not monitor for that. A pool with a well installed equipotential bonding system installed should shunt any current away from users. Current is still there, but finds paths of lower resistance than the user to follow. If some item is missed when making up the bonding system that is where dangerous potentials may show up or if some part of the bonding system is damaged.
There are such devices. Usually found on portable cordsets with integral GFCI. There must be full voltage before they will reset, and if any supply conductor is interrupted they drop out.
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