TRANSFORMERS - A solid connection from primary to secondary ?

[don_resqcapt19]

Inside the demarcation box is a grounding post that I touched accidentally when I got the buzz.

Then the pool perimeter that you were sitting on or the bonding post was not connected to the electrical grounding system. Or maybe you were touching the earth outside of the bonded perimeter. The whole purpose of the bonding is to raise the voltage of all bonded parts to the same voltage.

 

[winnie]

Replying to my own post because it is far too late to edit the typo:

The phone company has it's own wires, and their ground is clearly not bonded to your electrical system ground. That is a serious problem that should be fixed. The elevated voltage might be coming from the poco lines.

Should read:
The phone company has it's own wires, and their ground is clearly not bonded to your electrical system ground. That is a serious problem that should be fixed. The elevated voltage might be coming from the phone company lines.

-Jon

 

[tortuga]

I recently participated in a discussion on another site where the design engineer was going to connect the neutral from the primary feeder to the XO on the secondary of a delta/wye transformer to avoid any requirements to provide a grounding electrode system for the transformer secondary. With the feeder neutral connected to the secondary XO, the transformer is not a separately derived system and the requirements in 250.30 do not apply.

Interesting,
so your saying I can install say a 50kVA transformer with a primary side of 480 delta and the secondary is 208Y/120 and all I need to do is pull a neutral from the 480 panel, sized to 250.122, to the XO side and that is NEC compliant? No GEC required?

 

[mtnelect]

Then the pool perimeter that you were sitting on or the bonding post was not connected to the electrical grounding system. Or maybe you were touching the earth outside of the bonded perimeter. The whole purpose of the bonding is to raise the voltage of all bonded parts to the same voltage.

The demarcation box is the original for the telephone wiring throughout the house when it was built in 1975 and I traced the grounding stud directly to the main electrical panel adjacent to it. The electrical utility pole has a 25K transformer not a 75K as I stated. Also, the pole has a bare copper wire covered with a hollow wooden molding extending from the transformer's center tap to the ground below.

 

[winnie]

Something doesn't add up.

You observed the pool being bonded to the electrical system ground.

You confirmed that the telephone demark ground terminal was connected to the electrical system ground.

Yet you measured 26V between these two _bonded_ conductors with a low impedance meter.

That implies that the bonding is not really present between the two points measured, or lots of amps are flowing.

Jon

 

[mtnelect]

Something doesn't add up.

You observed the pool being bonded to the electrical system ground.

You confirmed that the telephone demark ground terminal was connected to the electrical system ground.

Yet you measured 26V between these two _bonded_ conductors with a low impedance meter.

That implies that the bonding is not really present between the two points measured, or lots of amps are flowing.

Jon

Thank you for your time and effort ... This is a great site !

Approximately 4 years ago, the water company was installing new meters. Their lateral from the street water main became PVC. At that time, I decided to upgrade to 3/4 " copper, so no bonding around the meter was needed. When the house was built, no ground rods were required. When the new copper lateral was installed an isolation fitting was used at the house. My house still has the original iron piping, which will be upgraded to copper this summer.

 

[winnie]

Thank you for your time and effort ... This is a great site !

Approximately 4 years ago, the water company was installing new meters. Their lateral from the street water main became PVC. At that time, I decided to upgrade to 3/4 " copper, so no bonding around the meter was needed. When the house was built, no ground rods were required. When the new copper lateral was installed an isolation fitting was used at the house. My house still has the original iron piping, which will be upgraded to copper this summer.

Is the lateral from the main PVC or copper? You say PVC but then you say upgrade to copper.

If the underground pipe is copper, then it is a grounding electrode and you need to bond around the meter.

Do you have any other grounding electrodes?

Did you confirm that you have good bonding from the electrical system grounding electrodes to the pool? Or did you see this bonding installed but have not checked its condition recently?

Did you confirm continuity from the telco ground terminal to the electrical system ground, or is this just a visual confirmation of wires?

-Jon

 

[mtnelect]

Is the lateral from the main PVC or copper? You say PVC but then you say upgrade to copper.

If the underground pipe is copper, then it is a grounding electrode and you need to bond around the meter.

Do you have any other grounding electrodes?

Did you confirm that you have good bonding from the electrical system grounding electrodes to the pool? Or did you see this bonding installed but have not checked its condition recently?

Did you confirm continuity from the telco ground terminal to the electrical system ground, or is this just a visual confirmation of wires?

-Jon

The street side is now PVC to the new 3/4 " water meter, then from the new meter, my new 3/4 " copper to my home.

 

[wwhitney]

from the new meter, my new 3/4 " copper to my home.

If that's underground and at least 10' long, then it is an available grounding electrode and needs to be bonded to the rest of the GES.

Cheers, Wayne

 

[mtnelect]

If that's underground and at least 10' long, then it is an available grounding electrode and needs to be bonded to the rest of the GES.

Cheers, Wayne

So, it looks like I am going to have to run a bonding wire from the front of the house to the back of the house where the main panel is located ?

 

[winnie]

If you have indoor metal piping, it should be bonded to your electrical system neutral.

If you have a qualifying underground pipe electrode, then you need a wire run to that electrode, you are not allowed to depend on the interior piping. As you note, there is an isolation fitting between the interior iron piping and the copper.

With that said, I don't think this currently isolated electrode is the source of the 26V you measured

Jon

 

[kwired]

Well I would respond that as far as ungrounded goes, that's how the grid started and there is still lots of delta distribution. Most of upstate NY is 4800 ungrounded Delta. I have never heard of any practical disadvantages of these systems, other than cost.

Do they still run a "shield conductor" and ground it often or even at every pole or other structure?

 

[kwired]

That looks like a two bushing transformer fed from two primary phases, not fed phase to neutral.

Now it is possible that one of the insulated wires on the cross bar is actually a neutral, but I think your local transformer is eliminated as the source of the elevated ground voltage you measured.

Jon

Only one of the primary lines has an overcurrent device in it though.

 

[kwired]

The street side is now PVC to the new 3/4 " water meter, then from the new meter, my new 3/4 " copper to my home.

So the water meter is not inside the home but rather in a pit or manhole probably at/near the tap from the main line?

If that copper line to the house is 10 feet or longer it qualifies as an electrode and must be used as part of the GES.

 

[electrofelon]

Do they still run a "shield conductor" and ground it often or even at every pole or other structure?

Not on distribution lines. Transmision and sub-transmission lines have the shield wire.