208v to ground 120v to neutral
- Thread starter Pscar55
- Start date
- Status
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Neutral floating, C phase loosely grounded.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
211103-1126 EDT
Pscar55:
Quite obviously C is grounded, and neutral is floating off of ground. Neutral is NOT grounded.
.
Pscar55:
Quite obviously C is grounded, and neutral is floating off of ground. Neutral is NOT grounded.
.
ptonsparky
Tom
- Occupation
- EC - retired
Make it 3.
N bot floating and c phase is not loosely gnded
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Like Gar said, neutral not bonded to ground, C phase faulted to ground.
Bonded to gnd at trans? It is. C phase seems to be wired properly
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Are you positive? The only way you can get the voltages you posted is a floating neutral. The C phase can be faulted to ground anywhere from the output, to a load faulted. Turn off all loads and see if the voltage changes.
I will try that again tomorrow. Thanks for the input
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
It may be a bad connection on the bond between XO and ground, could be burnt from the fault on C phase.
acin
Senior Member
- Location
- pacific grove california
- Occupation
- general building contractor est.1984 . C 10 elec. lic.as of 8 / 7/ 2020
Im still learning . b to e is e earth?
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Probably a typo.
ptonsparky
Tom
- Occupation
- EC - retired
I agree with the first 2, so make make it 3.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
I agree that the voltages seen look like a 'corner grounded' system.
If on physical inspection the system appears to be neutral grounded, then there must be _two_ faults, a broken ground connection and a phase to supposedly grounded metal fault.
Remember that soil is not some magical sink for electricity. It is a conductor. A fairly poor but very large conductor.
The neutral could be grounded at the transformer but floating at the service, and then a phase to enclosure fault would look like a corner grounded system. This could be very dangerous because all bonded metal in the building would be at 120V relative to remote earth.
How about neutral grounded at the transformer to an electrode there.
To the OP when you make measurements again please specify where you are making them. By 'a to ground' I presume you had one meter probe on the a phase and one on something like a ground bus.
Did you try different 'ground ' points? Did you try measuring voltage between different ground points?
Is this problem at a service or a subpanel or at a junction box somewhere?
Jon
If on physical inspection the system appears to be neutral grounded, then there must be _two_ faults, a broken ground connection and a phase to supposedly grounded metal fault.
Remember that soil is not some magical sink for electricity. It is a conductor. A fairly poor but very large conductor.
The neutral could be grounded at the transformer but floating at the service, and then a phase to enclosure fault would look like a corner grounded system. This could be very dangerous because all bonded metal in the building would be at 120V relative to remote earth.
How about neutral grounded at the transformer to an electrode there.
To the OP when you make measurements again please specify where you are making them. By 'a to ground' I presume you had one meter probe on the a phase and one on something like a ground bus.
Did you try different 'ground ' points? Did you try measuring voltage between different ground points?
Is this problem at a service or a subpanel or at a junction box somewhere?
Jon
ptonsparky
Tom
- Occupation
- EC - retired
Is this a new install?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Then explain the voltage readings.
ptonsparky
Tom
- Occupation
- EC - retired
Exactly what is 'gnd'?
Sarge56
Member
- Location
- Auburn High School, Rockford, IL
- Occupation
- Instructor, electrician
We had an ungrounded 3-phase system, 480 volt. 3 lights at 1200 amp panel that would indicate a ground fault. I did not know about this system at the time. When troubleshooting a machine, I got 480 between 2 phases and 480 to ground. Near heart attack. Turned out that another machine no way nearby had a ground fault at the motor leads.
He says it is not grounded but there may be an unintentional ground fault. And it could be anywhere. The only way you can get those readings is either through an intentional or unintentional grounded phase C. If it were me doing this, I would determine if the trans is delta or wye. If wye, ground the center point. I totally miss this work.
He says it is not grounded but there may be an unintentional ground fault. And it could be anywhere. The only way you can get those readings is either through an intentional or unintentional grounded phase C. If it were me doing this, I would determine if the trans is delta or wye. If wye, ground the center point. I totally miss this work.
- Status