I have 25kva 120/240 service transformer. I measure 126 on each phase and 252 between the phases. When the transformer is connected to a sevice entrance there is a potential difference between the transformer's nuetral and the sevice entrance ground of 3 volts. This 3 volts cause arcing on the casing of the well, which is grounded, fed of this sevice. why there is 3 volt differce between the two grounds? How to get rid of this 3 volt differential ???
Grounding Problem
- Thread starter Basra123
- Start date
- Status
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: Grounding Problem
Where in the distribution system is the separately derived system's (transformer secondary) neutral bonded to ground? Is there a grounding electrode conductor run from the XO of the transformer to the grounding electrode system?
Where in the distribution system is the separately derived system's (transformer secondary) neutral bonded to ground? Is there a grounding electrode conductor run from the XO of the transformer to the grounding electrode system?
bphgravity
Senior Member
- Location
- Florida
Re: Grounding Problem
This 3 volts is the voltage drop on the service neutral. I doubt you have a real problem if all bonding and grounding is performed correctly at the transformer and at the service, save for possibly and undersized grounded conductor.
This 3 volts is the voltage drop on the service neutral. I doubt you have a real problem if all bonding and grounding is performed correctly at the transformer and at the service, save for possibly and undersized grounded conductor.
- Location
- Illinois
- Occupation
- retired electrician
Re: Grounding Problem
Is the transformer a "service transformer or SDS?Where is the main or system bonding jumper? Where exactly are you placing the meter leads to read the 3 volts?
Don
Is the transformer a "service transformer or SDS?Where is the main or system bonding jumper? Where exactly are you placing the meter leads to read the 3 volts?
Don
- Status