Single Wire Utility Transformers?

G

garbo

Senior Member
Frank DuVal said:
?????

Two wires go from substation to pole pig. What does it matter if we call one wire a phase or a neutral if the voltage feeding the pole pig primary matches? NO WHERE is the return current from the pole pig going through the earth unless the "return" conductor is snapped free, same as if a phase is snapped free!
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In my area they never run what you term 2 wite pole pig. Even when there is 3 phase then only run one high voltage wire to transformer. Like I said in early post my thinking is they lazy cheap ultility company is using every copper water service, steel gas pipe & cast iron soil pipe to back feed such connections. Why would copper water service have a 1/4 to 1/2 amp of current flow when the meter is pulled and no power in the house?
 
don_resqcapt19

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
garbo said:
In my area they never run what you term 2 wite pole pig. Even when there is 3 phase then only run one high voltage wire to transformer. Like I said in early post my thinking is they lazy cheap ultility company is using every copper water service, steel gas pipe & cast iron soil pipe to back feed such connections. Why would copper water service have a 1/4 to 1/2 amp of current flow when the meter is pulled and no power in the house?
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Because it is a parallel path for the service neutral conductor for all of the buildings in the area that are connected to the common underground metal water pipe system. In my area, it is common, to find 20% or more of the neutral current on the water piping system even where the service neutral is in perfect condition. Copper water service lines will have a resistance that is much lower than the aluminum neutral in the service drop or service lateral. Same with the cast iron mains that the copper service lines are connected to.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
garbo said:
lazy cheap ultility company is using every copper water service, steel gas pipe & cast iron soil pipe to back feed such connections.
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I don't know exactly what you mean by "backfeed", but note the power company does indeed have a second dedicated conductor powering the transformers.

As Don says, yes there is other stuff in parallel with the utilities neutral, but the current on the water pipe isn't necessarily primary neutral current. It could very well be secondary neutral current and is a consequence of grounded electrical systems served from the same transformer. Grounded electrical systems have advantages and disadvantages, just like almost everything.
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
garbo said:
Like I said in early post my thinking is they lazy cheap ultility company is using every copper water service, steel gas pipe & cast iron soil pipe to back feed such connections. Why would copper water service have a 1/4 to 1/2 amp of current flow when the meter is pulled and no power in the house?
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I think that the voltages that cause those currents would be more hazardous to people without that parallel metallic pathway to bond metallic surfaces, such as between electrical appliances and plumbing.

Back when electrical distribution was new, system grounding was not a definite thing. Some systems were grounded, and some weren't, and it became ubiquitous because it was proven to be safer overall.
 
kwired

kwired

Electron manager
Location
NE Nebraska
garbo said:
In my area they never run what you term 2 wite pole pig. Even when there is 3 phase then only run one high voltage wire to transformer. Like I said in early post my thinking is they lazy cheap ultility company is using every copper water service, steel gas pipe & cast iron soil pipe to back feed such connections. Why would copper water service have a 1/4 to 1/2 amp of current flow when the meter is pulled and no power in the house?
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The other side of the transformer is connected to the grounded conductor.

The grounded conductor of the primary and the grounded conductor of the secondary are both grounded, therefore are the same potential, and are also bonded together to help assure they remain same potential. Does no good to run a separate primary neutral and secondary neutral between two poles if you are going to bond them together and connect to same electrode at each pole, they just become a parallel set if you do. So for majority of applications within cities/towns where there is both primary and secondary conductors between poles, there is only one grounded conductor and it is shared with both primary and secondary.

The fact we use grounded conductors as a normal current carrying conductor is what introduces the stray voltage issues. If a conductor is carrying current there is a voltage drop across that conductor. We bond all sorts of non current carrying objects to the grounded conductor to lessen voltage potential between objects, but a side effect is any voltage drop imposed on the conductor is extended everywhere to the bonded objects.

Things like swimming pools where this "stray voltage" is more of a problem, we have more stringent rules and bond even more objects together to attempt to make it so that users of the pool can not contact objects of different potential at same time. The voltage to true earth is still there we just trying to make it so the entire pool is at whatever potential the incoming grounded conductor is.

Using a MGN system offers benefits for ways of dissipating transient voltages, particularly those caused by lightning.
 
don_resqcapt19

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
kwired said:
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Things like swimming pools where this "stray voltage" is more of a problem, we have more stringent rules and bond even more objects together to attempt to make it so that users of the pool can not contact objects of different potential at same time. The voltage to true earth is still there we just trying to make it so the entire pool is at whatever potential the incoming grounded conductor is.

...
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Exactly...we try to energize the pool equipment and everything within touch of the pool.
 
mtnelect

mtnelect

HVAC & Electrical Contractor
Location
Southern California
Occupation
Contractor, C10 & C20 - Semi Retired
don_resqcapt19 said:
Exactly...we try to energize the pool equipment and everything within touch of the pool.
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Glad to see the responses on this issue. Seems that a lot of folks didn't know this. It's all about the utilities trying to save money on the consumers backs. So you got to install a grounding mess around your pool with copper. So the utilities don't have to pay for it.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
mtnelect said:
So, put a amp probe around your water service. Where did that come from ?
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probably from other houses served from the same transformer. That is a consequence of grounded systems. I happens even on a delta distribution system and has nothing to do with the utility.

mtnelect said:
It's all about the utilities trying to save money on the consumers backs. So you got to install a grounding mess around your pool with copper. So the utilities don't have to pay for it.
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WE pay for utility distribution costs not the utility. MGN is saving us money not the utility.
 
mtnelect

mtnelect

HVAC & Electrical Contractor
Location
Southern California
Occupation
Contractor, C10 & C20 - Semi Retired
electrofelon said:
probably from other houses served from the same transformer. That is a consequence of grounded systems. I happens even on a delta distribution system and has nothing to do with the utility.


WE pay for utility distribution costs not the utility. MGN is saving us money not the utility.
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So, shut up and sit down. It's the price you pay for "Cheep" electricity.
 
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