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Discussion Starter · #61 ·
The neutral support wire you describe is a neutral, not a ground. If they didn't need the neutral it wasn't connected.

If the 480V service is supplying loads that do not require a neutral, say an MCC, why would one be installed? But normally you would still bond it to ground.

Back to the buried ground. Yes that's not the way it would be done today, but back in the day who knows what they did? There may be an entire ground grid installed at that location. Tell you what, instead of digging up the ground next time you're there:D, how about you string out a piece of wire between the utility and the buildings's ground and take a measurement. I don't have to tell you to check for voltage first.
LOL. Could be a shocking revelation
 

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Discussion Starter · #63 ·
Give us an update when you go back, please. Pics would be nice.
I do plan to get pics and a detailed explanation of them, next time i go. speaking of which, can i load a video to here from my phone ? and i will also check the ground potentials
 

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Discussion Starter · #64 ·
I work on a couple of sites that look like that. Sorry I didn't take any pictures. On one, the customer owns the 2400v un-grounded Delta primary distribution and our three tubs give us 480v un-grounded Delta. There are (12) 120 volt type A lamps wired in series/parallel as a ground fault indicator connected to the 480v circuit. All constructed some time in the '50s.
On another site we also have installed a few custom built pad mounted transformers with customer owned 26kv un-grounded delta primaries to 480v un-grounded delta secondaries. Eaton made some custom built ground fault indicators for our new MCCs for these, no 120v type A lamps in the new installations.
These un-grounded type of services are designed/installed where continuous processes are critical. First short to ground anywhere on the plant only sets off an alarm and doesn't blow any fuses or trip any circuit breakers or shutting down a continuous process. It allows for clearing of belts and crushers for an orderly manual shutdown after an alarm is sensed..
 

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Bilge Rat
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now to ask the question in a different way ..... is there such a thing as floating Y ?
Yes, as long as the center of the Y is not connected to anything, it'd be a floating Y.

An example of this would be when back-feeding a 480∆ - 120/208Y transformer in order to get 480 from a 208 service. If X0 is connected to either the neutral or the ground, there'll be circulating currents that will eventually burn up the transformer. But if X0 is isolated there are no circulating currents, therefore this is the proper way to connect it.
 

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If the 480V service is supplying loads that do not require a neutral, say an MCC, why would one be installed? But normally you would still bond it to ground.
Had this happen a few years ago at my former job. Disconnected a floating Delta in the MCC, good old Unitrol, and powered it up with a Star. The neutral was landed on the grounded ground bar and off we went. There were no 277 loads so it was just grounded and that was that.
There were ground rods driven in addition to the steel deep well casing and the de facto Ufer from the rebar work all lashed together
to the iron work. This was already present. The ground system on r-mix plants are what some consider over the top, but the 75’ tall silo or silos make great lightning rods that we have to dissipate the energy quickly.
 

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Holy cannoli a lot of all caps posts and frustration to read through in the beginning of this thread.

I make a motion to re-name this configuration after the OP, the A.R. Special.
 

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Discussion Starter · #69 ·
Had this happen a few years ago at my former job. Disconnected a floating Delta in the MCC, good old Unitrol, and powered it up with a Star. The neutral was landed on the grounded ground bar and off we went. There were no 277 loads so it was just grounded and that was that.
There were ground rods driven in addition to the steel deep well casing and the de facto Ufer from the rebar work all lashed together
to the iron work. This was already present. The ground system on r-mix plants are what some consider over the top, but the 75’ tall silo or silos make great lightning rods that we have to dissipate the energy quickly.
So .... you started with "had this happen a few years ago" i follow your description of the situation, but i dont find your description of what happened?
 

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Discussion Starter · #71 ·
Holy cannoli a lot of all caps posts and frustration to read through in the beginning of this thread.

I make a motion to re-name this configuration after the OP, the A.R. Special.
After enough replies, I found a way to rephrase the question and got an immediate answer that answered my op perfectly

as far as the AR Special, you might want to reserve that title for my post Odd Problem - Voltage on Metal Roof.
 

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So .... you started with "had this happen a few years ago" i follow your description of the situation, but i dont find your description of what happened?
My post was a response to @joe-nwt query/statement about a MCC with no neutral load, just phase to phase loads.
BTW, everything worked out just perfectly at that plant.
 

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Discussion Starter · #73 ·
My post was a response to @joe-nwt query/statement about a MCC with no neutral load, just phase to phase loads.
BTW, everything worked out just perfectly at that plant.
My bad ... this has generated so much response that i am scrambling to keep up. I did not notice that was not directed to me. however i am curious so i will go back and read the whole thing
 

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Discussion Starter · #75 ·
Ungrounded wye is standard on ships and is also very common in Europe, it's called an IT system over there.
Ungrounded wye is standard on ships and is also very common in Europe, it's called an IT system over there.
When i was working off shore drilling. I discovered that you needed a 2 pole breaker for 120V. The panel was 2 phases (same as our common single phase panels at home) the voltage was 60/60/120. the panel had a 4 wire feed. I had no clue about the txr, i didnt even know there were choices at that time. I recognized the methods of wiring as ship board from my time in the navy
 

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When i was working off shore drilling. I discovered that you needed a 2 pole breaker for 120V. The panel was 2 phases (same as our common single phase panels at home) the voltage was 60/60/120. the panel had a 4 wire feed. I had no clue about the txr, i didnt even know there were choices at that time. I recognized the methods of wiring as ship board from my time in the navy
That's awesome, that's one area I haven't worked. Although typically I will see 69 volts to ground on a well functioning system. Or 277 if it's a 480VAC system.
 

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Discussion Starter · #77 ·
That's awesome, that's one area I haven't worked. Although typically I will see 69 volts to ground on a well functioning system. Or 277 if it's a 480VAC system.
ok ,,, that 69V has me intrigued. Are you talking about an ungrounded system? 120V phase to neutral?
 

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Bilge Rat
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I've seen 69/120 for metering in medium-voltage switchboards.

It's 3 - 120 volt transformers connected 4 wire Y. 69 phase to neutral and 120 phase to phase.

Fairly common for voltage and KVA/KW metering.
 
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