natfuelbill
Senior Member
Can three phase distribution equipment (panelboard) be used to distribute single power?
If existing, have you determined the load on the 208/120 panel? Can you flop all the third phase over to single phase? Are there any 4-wire circuits? Have you looked into making the service corner grounded?The existing installation was installed by others. A three phase service 480v 200a to a three wire feeder (no EGC no grounded conductor no metal conduit) to a 480 to 208/120 step down xfrmr. One primary coil went to ground. I want to re-purpose one of the phase wires as a EGC and install a 480 to 120v single phase xfrmr.
Feed the three phase panel with 120/208v.
The existing installation was installed by others. A three phase service 480v 200a to a three wire feeder (no EGC no grounded conductor no metal conduit) to a 480 to 208/120 step down xfrmr. One primary coil went to ground. I want to re-purpose one of the phase wires as a EGC and install a 480 to 120v single phase xfrmr.
Feed the three phase panel with 120/208v.
Are there any shared neutral conductors, especially on the circuits that are connected to the third Line?The loads are all 120v. Consisting of electronics and lights. The three phase was for an air compressor that has been removed.
One of the 480V 3? conductors is grounded. Did anyone even check to see if it is already grounded? Is there a ground detector on the system? Or is the service 480/277? You did not say what the service actually is... only that the feeder was ungrounded... but are you certain of this?Corner grounded has not been considered. Can you explain?
From a safety standpoint, yes... but if the service really is ungrounded, an EGC would not serve any purpose if there is no ground detector.The real Deficiency is the missing EGC in the primary feeder.
He's lost 1/3 of the existing xfmr's kVA rating. How would this be 1.73 times more power than a fully-functioning, same-kVA-rated replacement xfmr?you will have 1.73 times more power available if you leave it as it is and it will not cost anything either. Assuming same KVA transformer. Why would you want to make these changes? ...
Just exactly what is there? Cable or wire in conduit? What type of conduit? Exposed subject to damage or not, or concealed, underslab/underground and not not subject to damage? ......a three wire feeder (no EGC no grounded conductor no metal conduit)...
If this were on MY property, I'd probably consider just isolating the faulty winding pair and flop the respective line branch circuits over to one of the other two functional lines... and consider alternatives later.Like i said this is what I found
Service is 480/277 3 phase 4 wire
Main is 200A fused 3 phase 480v rated
Feeder is 3-#4/0 in buried PVC conduit 1200' long.
Transformer is 45 kva 480 pri 208/120 sec
480 v three phase disconnect tied off tranny primary. Was for a removed air compressor.
Tranny feeds a 208/120v 200a main breaker panel.
There are only 5 120v 1p 15a branch breakers in a three phase panel.
Total load is 3000 watts only!
I am thinking of using the existing main disconnect with only two fuses.
Repurpose one of the phase conductors to be an EGC.
Replace tranny with 480 to 120/208 single phase tranny.
Replace secondary panelboad with single phase.
PS: Do you realize that if you should find a 120/208 1? xfmr, you will not be able to retask one conductor as an EGC. A 120/208 secondary would require a 3? primary....
But I am still wondering just where you plan to get a 120/208 1? xfmr...??? FWIW, you already have one... :roll::roll::roll:
He's lost 1/3 of the existing xfmr's kVA rating. How would this be 1.73 times more power than a fully-functioning, same-kVA-rated replacement xfmr?
Say the tranny is to remain three phase, and the three phase conductors remain as phase conductors.
Can an EGC be added to the circuit by burying it? Ie NOT installed in the same PVC conduit as the phase conductors?