A phase 95 volts

[fayc12]

Good Morning,

ATS 3 pole 4 wire 120/208 volts


Load side of ATS:

Phase A-B 208 volts

Phase B-C 208 volts

Phase C-A 208 volts


A phase to Neutral 120 volts

B phase to Neutral 120 volts

C phase to Neutral 120 volts


A phase to equipment ground 120 volts

B phase to equipment ground 120 volts

C phase to equipment ground 120 volts


Distribution Panel fed from Load side of ATS


Feeder Breaker at the Distribution Panel

Phase A-B 208 volts

Phase B-C 208 volts

Phase C-A 208 volts


A phase to Neutral 120 volts

B phase to Neutral 120 volts

C phase to Neutral 120 volts


A phase to equipment ground 120 volts

B phase to equipment ground 120 volts

C phase to equipment ground 120 volts


Feeder breaker at the Distribution panel that

Feeds panel on the 1st floor, 2nd floor and 3rd floor


1st floor panel MLO feeds thru to the 2nd floor panel

(No breaker in the first floor panel to feed 2nd floor.)


2nd floor panel MLO feeds thru to the 3rd

(No breaker in the 2nd floor panel to feed 3rd floor.)
3rd floor panel MLO.


Now the fun begins

1st floor Panel

Phase A-B 208 volts

Phase B-C 208 volts

Phase C-A 208 volts


A phase to Neutral 95 volts

B phase to Neutral 151 volts

C phase to Neutral 168 volts


A phase to equipment ground 120 volts

B phase to equipment ground 120 volts

C phase to equipment ground 120 volts


2nd floor Panel

Phase A-B 208 volts

Phase B-C 208 volts

Phase C-A 208 volts


A phase to Neutral 95 volts

B phase to Neutral 151 volts

C phase to Neutral 168 volts


A phase to equipment ground 120 volts

B phase to equipment ground 120 volts

C phase to equipment ground 120 volts


3rd floor Panel

Phase A-B 208 volts

Phase B-C 208 volts

Phase C-A 208 volts


A phase to Neutral 95 volts

B phase to Neutral 151 volts

C phase to Neutral 168 volts


A phase to equipment ground 120 volts

B phase to equipment ground 120 volts

C phase to equipment ground 120 volts


Lights dim and flickering

UPS’s in alarm

Patient Monitors shutting down etc… on all three floors


What was going on for work…Removing the over bed patient room lights.


In those lights are a normal branch circuit and an emergency branch circuit separate from each other. Including the neutral.


How the situation temporarily was corrected…


Go back to each of the patient room lights that were removed

And connect the neutral from the normal branch circuit to the neutral of the emergency branch circuit. And everything went back to normal. ?????
Which is not normal.

Any ideas or thoughts….Thank You

 

[LarryFine]

Welcome to the forum.

It sounds to me like a break in the normal-power neutral pathway.

 

[petersonra]

I would guess that the neutral was not run in the feeder to the panel displaying the odd line to neutral voltages, or has come loose.

 

[fayc12]

I would guess that the neutral was not run in the feeder to the panel displaying the odd line to neutral voltages, or has come loose.

Thank You
review very old plans now

 

[fayc12]

I would guess that the neutral was not run in the feeder to the panel displaying the odd line to neutral voltages, or has come loose.

I am thinking lose somewhere
Thank You

 

[hillbilly1]

Neutral pole on transferswitch burnt or open on normal (utility side)

 

[hillbilly1]

Re-read the original post, so the dp voltage’s are good, but the panel is not? How did you connect the emergency source neutral to the normal? And in the dp, was the rest of the loads three phase not requiring a neutral? Was the feeder to the panels on when the voltage was checked at the dp? The most common failure point would be the transferswitch, it would be strange that the feeder neutral would have became open all of the sudden. Check across the neutral contact on the transferswitch, first for voltage, if none, check continuity.

 

[hillbilly1]

Just seen you have a three pole switch, so scratch that.