Power Line to my house was broken

MossRoad · Mar 29, 2021

Here's the one that feeds my house, and 11 other houses.

The top three wires are 3 phase, all hot, no neutrals.

One wire comes from 1 phase and feeds the top of the transformer.

Another wire comes off the top of the transformer and connects to both the overload and ground down the side of the pole. Again, no neutral.

The three secondaries are two 120v hots and a neutral. They go to the lines that feed the 12 houses. That's the only neutral on that pole. It doesn't go back to the power source. There is no neutral back to the power company source that I can see.

Industrial Toys · Mar 29, 2021

What confusion! Pictures of TRUCKS, some random wire lying on the ground with no reference where it was connected or coming from, other pictures of OTHER transformers, sketches. NOTHING giving an accurate picture of what is the true situation.

Mixing up talk of single phase, three phase, secondary subscriber circuit, primary high voltage circuit. Neutrals, pole (Earth) grounds, metalic grounding circuits . Some more Generic sketches!

I do have little doubt, that whatever it turns out to be, it isn't dangerous if the Utility doesn't think it is.

I also have little doubt that a High line voltage circuit feeding a transformer would not work well, if at all using an EARTH circuit for return.

civilian · Mar 29, 2021

So can someone explain how one wire goes into transformer and three wires come out?

My house is over 1200ft from the road. Power company plowed in one line and set transformer at the end. Told me it is a primary wire. Tapped into top line at street and only one fuse thingy at pole (I think). My transformer is on the ground, at my meter board panel. That board panel has the meter box, and two panels, one for the house and the other for the workshop. From those 2 panels, buried in conduit are four wire each going to the house or the workshop. So transformers take one primary wire and convert it to three wires, correct?

Another dumb, non understanding high voltage consumer. (After it is in my panels with 120v and 240v I can understand and work with that.) Thanks, Jon

MossRoad · Mar 29, 2021

Talk about confusion, it took me a while to figure out what this "hydro" is you guys keep talking about.

MossRoad · Mar 29, 2021

civilian said:
So can someone explain how one wire goes into transformer and three wires come out?

My house is over 1200ft from the road. Power company plowed in one line and set transformer at the end. Told me it is a primary wire. Tapped into top line at street and only one fuse thingy at pole (I think). My transformer is on the ground, at my meter board panel. That board panel has the meter box, and two panels, one for the house and the other for the workshop. From those 2 panels, buried in conduit are four wire each going to the house or the workshop. So transformers take one primary wire and convert it to three wires, correct?

Another dumb, non understanding high voltage consumer. (After it is in my panels with 120v and 240v I can understand and work with that.) Thanks, Jon

It has to do with the windings in the transformer.

Voltage into a coil induces a magnetic current in the primary windings. That transfers into a magnetic current in the secondary windings.

If you put a wire at the center of the secondary windings that's the neutral point.

You go up the winding X number of coils from the center tap until you find a point that's 120V potential from the neutral point.

Then you go down the winding X number of coils from the center tap and you find 120V opposite from the neutral point.

The potential between the upper tap and neutral is 120V.
The potential between the lower tap and neutral is 120V.
The potential between the upper and lower taps is 240V.

If you have 7200V coming in, you use a step-down transformer to get 120V split phase. It's a single phase 7200V coming in. The transformer splits the phase into 2 hot legs. It's still single phase power, but it's split phase.

Clear as mud?

MossRoad · Mar 29, 2021

k0ua said:
Coobie, please correct me if I am wrong, but isn't the reason Eddie still has electrical service is because current is flowing in the actual earth, the land under his feet to complete his electrical circuit?.

It is not near as good as that wire that is laying on the ground, but connections on poles with their copper ground wires going into the actual earth on both sides of the broken wire are now carrying the entire load of his residence. This is not a particularly good thing to have those currents flowing in the ground instead of that wire, but that is my understanding of how he still has service.

For those that don't know, Coobie is a retired electrical lineman, and certainly has far more experience and knowledge than I about these things.

Yes. Coobie could clear this up.

Industrial Toys · Mar 29, 2021

My Guess is that the centre conductor of the three is the neutral/ground, and probably is also used for the primary of the transformer.

This may seem odd, but I can't see them running two neutral/grounds, one for the primary and the other for the secondary and customers.

civilian · Mar 29, 2021

MossRoad said:
It has to do with the windings in the transformer.

Voltage into a coil induces a magnetic current in the primary windings. That transfers into a magnetic current in the secondary windings.

If you put a wire at the center of the secondary windings that's the neutral point.

You go up the winding X number of coils from the center tap until you find a point that's 120V potential from the neutral point.

Then you go down the winding X number of coils from the center tap and you find 120V opposite from the neutral point.

The potential between the upper tap and neutral is 120V.
The potential between the lower tap and neutral is 120V.
The potential between the upper and lower taps is 240V.

If you have 7200V coming in, you use a step-down transformer to get 120V split phase. It's a single phase 7200V coming in. The transformer splits the phase into 2 hot legs. It's still single phase power, but it's split phase.

Clear as mud?

Thanks, yes clear as mud. I probably learned about transformers in college many years ago. But didn't do good in those electrical courses for mechanical engineers. Didn't use that very much either. Jon

MossRoad · Mar 29, 2021

Industrial Toys said:
My Guess is that the centre conductor of the three is the neutral/ground, and probably is also used for the primary of the transformer.

This may seem odd, but I can't see them running two neutral/grounds, one for the primary and the other for the secondary and customers.

Yeah, seem there's gotta be a neutral in there somewhere. I wonder if the center tap of the secondaries is tied into a return somehow? I need to take a longer walk and see where it goes.