Remote SDS GES

[Dsg319]

I have a small 15kva or smaller single phase 480v-120/240v. Transformer to be installed outdoors on a strut rack that will be supplying a small 12 space panel.

It is over 100ft away from being able to tie into the station grounding system.

Am I good to pound to rods for my GES or does would both GES have to be tied together?

Code book is out in my truck. Mind is running while laying in bed lol.

 

[augie47]

Establish a GES at the new location.

 

[infinity]

Establish a GES at the new location.

My thought as well, pound in two rods for the GES and connect the transformer to it. Would the panel also require the GES if there is no structure?

 

[Dsg319]

My thought as well, pound in two rods for the GES and connect the transformer to it. Would the panel also require the GES if there is no structure?

I ended up connecting the panel to the GES as well. Energized and tested it out today as well as one other small SDS I checked out and noticed when taking voltage readings from phase to ground with my LOW IMPEDANCE meter it would only show around 30-50vac instead of 120.

I assume this is because of the high resistance of the new GES?

 

[jaggedben]

If the panel and transformer are on the same rack then that's one structure and only needs one GES.

The voltage is not what it should be. I suspect you may be missing a system bonding jumper which is a serious safety issue and more important than the GES. Your system isn't really grounded if the voltage to neutral is different than the voltage to ground.

 

[stretch12]

I’d say the transformer x o is not bonded.
Giving you weird readings.

 

[don_resqcapt19]

I ended up connecting the panel to the GES as well. Energized and tested it out today as well as one other small SDS I checked out and noticed when taking voltage readings from phase to ground with my LOW IMPEDANCE meter it would only show around 30-50vac instead of 120.

I assume this is because of the high resistance of the new GES?

Exactly where did you take the voltage rating? I sounds like you forgot the system bonding jumper.

 

[stretch12]

Some not all transformers do not have an intrergal xo to ground connection, you need that on a delta / wye setup, with whatever electrodes you choose. Ie building steel? To give the reference. Of a grounded conductor.
Sorry long day prob didn’t explain as best as I could

 

[Dsg319]

To clear things up when I say ground I mean dirt, not an EGC or SSBJ.

I should have said to begin with the way the word ground gets throwed around.

System bonding jumper is installed on both systems I checked.

The one I installed myself. The existing one i could see and checked for continuity.

I took my meter off Low Impedance and voltages was as they should be.

 

[augie47]

Some not all transformers do not have an intrergal xo to ground connection, you need that on a delta / wye setup, with whatever electrodes you choose. Ie building steel? To give the reference. Of a grounded conductor.
Sorry long day prob didn’t explain as best as I could

In my experience that :"some" has been non-existent. Many have a "bond strap" that connects the core to case and that is often mis-identifed as an XO bond.

 

[Dsg319]

And my neutral in this case is an X6. And bonded in the disconnect.

It’s a 3ph9kva 480d/240d120ct. (Delta high leg)

 

[Dsg319]

Exactly where did you take the voltage rating? I sounds like you forgot the system bonding jumper.

From line 1, line 2 to earth ground in disconnect where all the bonding and grounding is at.

 

[don_resqcapt19]

From line 1, line 2 to earth ground in disconnect where all the bonding and grounding is at.

By "earth ground" do you mean grounding electrode conductor? Was this connector connected to anything in the disconnect "where all of the bonding and grounding is at"?

 

[Dsg319]

By "earth ground" do you mean grounding electrode conductor? Was this connector connected to anything in the disconnect "where all of the bonding and grounding is at"?

I’m sorry I worded that very poorly.

My reading was from line1 and line2 terminals in the disconnect to the physical dirt of the earth.

What spiked my interest in this was knowing that I had installed the new GES for this sds and figured it has a far higher resistance to earth compared to our homes GES because of the utilities Multi point grounded neutral.

So I literally took a reading from the ungrounded conductor to a screw driver stuck in the earth.

 

[Little Bill]

I’m sorry I worded that very poorly.

My reading was from line1 and line2 terminals in the disconnect to the physical dirt of the earth.

What spiked my interest in this was knowing that I had installed the new GES for this sds and figured it has a far higher resistance to earth compared to our homes GES because of the utilities Multi point grounded neutral.

So I literally took a reading from the ungrounded conductor to a screw driver stuck in the earth.

I don't know why you would want to measure that. The earth is a good conductor, but the problem is it has too many paths that current can take.

 

[Dsg319]

I don't know why you would want to measure that. The earth is a good conductor, but the problem is it has too many paths that current can take.

Curiosity out of knowing the GES was just two rods for this separately derived system and likely had a high resistance comepared to most. SoI was curious as to what voltage reading to earth “dirt” was.

I’m aware the connection to dirt has nothing to play in the events of clearing faults but is for lightning/transients.

Just curiosity is all. Sometimes my mind takes me on rabbit trails.

 

[don_resqcapt19]

I’m sorry I worded that very poorly.

My reading was from line1 and line2 terminals in the disconnect to the physical dirt of the earth.

What spiked my interest in this was knowing that I had installed the new GES for this sds and figured it has a far higher resistance to earth compared to our homes GES because of the utilities Multi point grounded neutral.

So I literally took a reading from the ungrounded conductor to a screw driver stuck in the earth.

If you installed it correctly the primary equipment grounding conductor will be connected to the secondary grounding electrode and the resistance will not be any different than it is at your house. The voltage should read the same as when you go from an ungrounded conductor to the dirt at your house.

 

[Dsg319]

If you installed it correctly the primary equipment grounding conductor will be connected to the secondary grounding electrode and the resistance will not be any different than it is at your house. The voltage should read the same as when you go from an ungrounded conductor to the dirt at your house.

You are correct I checked even another source from ungrounded conductor to actual earth and I received around the same reading.

I guess I just have never took such a reading with my meter on Low impedance mode and it lets enough current through and causes a voltage drop across it to earth.

 

[texie]

In my experience that :"some" has been non-existent. Many have a "bond strap" that connects the core to case and that is often mis-identifed as an XO bond.

Scary, but true. I've encountered many who do not understand the core to case strap.