Could utility have caused damage to fixtures?

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brantmacga

brantmacga

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I finished the project back in February. My part of the job is a large baseball park with concession and support building.

During construction the owner erected a steel maintenance building under a separate contract and someone else did the electrical installation.

Friday, the utility de-energized my service, presumably to set an additional transformer for the maintenance building.

Owner called me yesterday when he arrived to start cooking concessions and found every GFCI breaker was tripped; all of the cooler/freezers were down over the weekend and no one knew; they lost everything. There are roughly 40 GFCI breakers.

He also told me several lights not working. I went up there today and sure enough several 277v lighting fixtures are dead. I have to warranty replace all of these now.

It doesn’t seem to be a coincidence that all of this stopped working. Any ideas as to what could’ve happened? I didn’t think to check the surge protectors while I was there. I have them on the 480v and 208v panels.


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I gotta agree that this more likely related than just pure coincidence. I wonder if they possibly had an open neutral. Maybe some else has a more plausible explanation.
 
If POCO technicians connected service Line-Line first, and neutral last, then MWBC wired lights could get 480v, and MWBC wired GFCI's could get 208v.
 
brantmacga said:
I finished the project back in February. My part of the job is a large baseball park with concession and support building.

During construction the owner erected a steel maintenance building under a separate contract and someone else did the electrical installation.

Friday, the utility de-energized my service, presumably to set an additional transformer for the maintenance building.

Owner called me yesterday when he arrived to start cooking concessions and found every GFCI breaker was tripped; all of the cooler/freezers were down over the weekend and no one knew; they lost everything. There are roughly 40 GFCI breakers.

He also told me several lights not working. I went up there today and sure enough several 277v lighting fixtures are dead. I have to warranty replace all of these now.

It doesn’t seem to be a coincidence that all of this stopped working. Any ideas as to what could’ve happened? I didn’t think to check the surge protectors while I was there. I have them on the 480v and 208v panels.


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Were they inside transformer or doing work on same pole if transformer(s) is on pole?

I am presuming they somehow were extending primary line(s) to supply an additional transformer for this maintenance building and work they did most likely should have only involved primary line work and they shouldn't have needed to touch any the secondary conductors supplying your installation. Though I suppose depending on details they still possibly could have opened your secondary neutral. That chance maybe higher if you are served by pole top than by padmount transformer though I think is still somewhat slim they would open the secondary neutral connections, but all depends on where and how things are connected.
 
kwired said:
Were they inside transformer or doing work on same pole if transformer(s) is on pole?

I am presuming they somehow were extending primary line(s) to supply an additional transformer for this maintenance building and work they did most likely should have only involved primary line work and they shouldn't have needed to touch any the secondary conductors supplying your installation. Though I suppose depending on details they still possibly could have opened your secondary neutral. That chance maybe higher if you are served by pole top than by padmount transformer though I think is still somewhat slim they would open the secondary neutral connections, but all depends on where and how things are connected.
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Can’t imagine they were in my transformer. The maintenance building is by the utility poles at the highway, my padmount is several hundred yards away.

Red line is underground primary to me. Blue square is maintenance building

6a544779e48127e7143605c08970087b.jpg



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Opening the service neutral would only have affected the 277 volt lights. The gfi’s would have come off a step down transformer, so they would not be affected, as that transformer does not need a neutral on the 480 volt side. Screwing up rotation on the poco side would only affect three phase motors, and would not affect the gfi’s. It is strange though all of this happened after the poco work was performed.
 
I'm thinking that sense you say they were only doing primary work maybe they had a single primary open. That can create odd voltages on the secondary.
 
total derail of thread...the print is a bit fuzzy, but I see a switch-controlled receptacle behind each pitcher's mound for pitching machines. Never saw that before, but I come from the low-rent part of town. :)
 
grich said:
total derail of thread...the print is a bit fuzzy, but I see a switch-controlled receptacle behind each pitcher's mound for pitching machines. Never saw that before, but I come from the low-rent part of town. :)
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Wiremold Ground Box. See bottom right corner.

And yeh we had extension cords running across the field when I was a kid.

32ba9a3c5c2d87ffc6950f6f07c7f0fb.jpg



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Perhaps there was ferroresonance occuring that was enabled, or at least enhanced, by the capacitance of the relatively long underground cable to the padmount. This would be more likely to occur if the pad mount was lightly loaded, and if they didn't switch on all three phases to the primary at the same time. Ferroresonance can produce higher voltages that could damage electronics such as drivers for lighting fixtures. Also, it might trip GFCIs due to the high frequency oscillations during ferroresonance.
But this is just speculation ...
 
synchro said:
Perhaps there was ferroresonance occuring that was enabled, or at least enhanced, by the capacitance of the relatively long underground cable to the padmount. This would be more likely to occur if the pad mount was lightly loaded, and if they didn't switch on all three phases to the primary at the same time. Ferroresonance can produce higher voltages that could damage electronics such as drivers for lighting fixtures. Also, it might trip GFCIs due to the high frequency oscillations during ferroresonance.
But this is just speculation ...
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Which can be pretty common to have individually operated cutouts/fuses to close one phase at a time.

Have heard of them having to close one phase then get two guys to close the remaining two at same time if they are having ferroresonance issues when using simple hot stick operated single pole switching devices.
 
synchro said:
Perhaps there was ferroresonance occuring that was enabled, or at least enhanced, by the capacitance of the relatively long underground cable to the padmount. This would be more likely to occur if the pad mount was lightly loaded, and if they didn't switch on all three phases to the primary at the same time. Ferroresonance can produce higher voltages that could damage electronics such as drivers for lighting fixtures. Also, it might trip GFCIs due to the high frequency oscillations during ferroresonance.
But this is just speculation ...
Click to expand...
He did say “several hundred yards away” with the UG lines feeding this pad mount.
Long line, pad mount,(5 leg?) and no loads..
Recipe for ferroresonance..
 
brantmacga said:
Can’t imagine they were in my transformer. The maintenance building is by the utility poles at the highway, my padmount is several hundred yards away.

Red line is underground primary to me. Blue square is maintenance building

6a544779e48127e7143605c08970087b.jpg



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Check the pad mount. See if the paint is bubbled or the XF looks different is some way.
Synchro may be on to something.
 
brantmacga said:
I finished the project back in February. My part of the job is a large baseball park with concession and support building.

During construction the owner erected a steel maintenance building under a separate contract and someone else did the electrical installation.

Friday, the utility de-energized my service, presumably to set an additional transformer for the maintenance building.

Owner called me yesterday when he arrived to start cooking concessions and found every GFCI breaker was tripped; all of the cooler/freezers were down over the weekend and no one knew; they lost everything. There are roughly 40 GFCI breakers.

He also told me several lights not working. I went up there today and sure enough several 277v lighting fixtures are dead. I have to warranty replace all of these now.

It doesn’t seem to be a coincidence that all of this stopped working. Any ideas as to what could’ve happened? I didn’t think to check the surge protectors while I was there. I have them on the 480v and 208v panels.


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How did they deenergize? At pole riser or with elbows in a vault? Sectionalizer?
 
Hv&Lv said:
He did say “several hundred yards away” with the UG lines feeding this pad mount.
Long line, pad mount,(5 leg?) and no loads..
Recipe for ferroresonance..
Click to expand...
I don't quite have a good grip on this ferroresonance stuff, but does that mean maybe less potential for such issues if cutouts were in much closer proximity to said transformer and they would have opened those cutouts to kill the transformer/closed them last when done working?
 
kwired said:
I don't quite have a good grip on this ferroresonance stuff, but does that mean maybe less potential for such issues if cutouts were in much closer proximity to said transformer and they would have opened those cutouts to kill the transformer/closed them last when done working?
Click to expand...
Ferroresonance has to have three things. A capacitive (long URD cable) and inductive reactance that are real close in value in series with each other. With no load on the transformer, a blown or opened fuse on the riser pole for a relatively extended time will start the transformer to rattling, which is the magnetostriction in the coil you are hearing, and oil heating enough to bubble paint.
 
Hv&Lv said:
Ferroresonance has to have three things. A capacitive (long URD cable) and inductive reactance that are real close in value in series with each other. With no load on the transformer, a blown or opened fuse on the riser pole for a relatively extended time will start the transformer to rattling, which is the magnetostriction in the coil you are hearing, and oil heating enough to bubble paint.
Click to expand...
So did they leave the thing "single phasing" for way too long or did opening/closing the circuit cause a voltage spike that damaged equipment? A little of both?
 
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