Ok. Well 1 situation is 480v 3wire - no neutral, to Disconnect run underground 600ft in pvc. From line side of 480v disconnect to Packing machine (480v) run in emt to disconnect at machine. On load side of the first disconnect is a Transformer to 240/120 single phase. Secondary loadcenter bonded to xformer and ground rod. How will a ground fault on 480v machine, or raceways blow fuse(s) at disconnect? No sign of ground fault monitoring device on premises. There is, however a wart-like appartatus as an appendix on the lower side knockout of the meter panel which I have been told by some is a lightning arrester.
Irrigation pump 480v 3wire no equipment ground??
- Thread starter gmsoucy
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walkerj
Senior Member
- Location
- Baton Rouge
Is the system an ungrounded Delta?
Are all metal parts bonded and grounded?
Are they at any point bonded to any phase winding?
Are all metal parts bonded and grounded?
Are they at any point bonded to any phase winding?
As far as being bonded to any phase wiring... not after the meter socket. I will be opening the meter socket to check what's happening there today. As far as delta, I will have to contact utility co Mon on that. As far as parts grounded.... grounded to what if there is no ground wire run? Bonded? Some is through emt some is not because if isolation by pvc conduit. I will no more by the end of the day.
walkerj
Senior Member
- Location
- Baton Rouge
Are the conductors in the PVC service conductors or feeders?
Technically they are feeders since the is a fused disconnect right on the pole next to the meter can. I will post photos or link to them. The service does appear to be corner grounded delta. However there is a separate ground run from overhead to the meter can. Ph1 to grd is 480v, Ph2 to grd is 0 (continuity), Ph3 to grd is 480v.
What is the appendix like device?
What is the appendix like device?
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here is what's overhead...
It seems to me that if Leg 1 or 3 faults to ground on equipment or raceway not bonded to either a separate equipment grounding conductor or (Leg 2?) and someone comes in contact with such a fault.... Whammo! Help to see it differently if need be...
It seems to me that if Leg 1 or 3 faults to ground on equipment or raceway not bonded to either a separate equipment grounding conductor or (Leg 2?) and someone comes in contact with such a fault.... Whammo! Help to see it differently if need be...
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strange animal.....
Your pictures look like a 4 wire system, but your voltage readings sound like a 480v corner grounded (or acccidently grounded) system.
The appendix like device appeasr to be a surge supressor/ lightening arrestor.
Your pictures look like a 4 wire system, but your voltage readings sound like a 480v corner grounded (or acccidently grounded) system.
The appendix like device appeasr to be a surge supressor/ lightening arrestor.
In your situation you need to start at Article 250.26 (4) then move to 250.28 and 250.32 then 250.50, 250.86 covers the metal raceway. These are just starting points,I think by the time you are done you will need to review most of article 250, so start reading.
Thanks for the reply. I have read the articles mentioned. Only the first article, to my observation, references the situation of one leg grounded. I understand that all metal boxes and raceways are to be bonded and grounded. My question is, does a separate equipment ground need to be run with the phase conductors when one of the phase conductors is grounded. The reason I ask is because they are currently run without an equipment ground. Should a new wire be run or should the grounded phase be bonded to raceways and metal boxes? I would think that a separate wire should be used as a equipment ground for safety if I were to think of that grounded phase as grounded conductor. Currently there is no connection or wire for equipment grounding purposes.
One of the equipment grounding conducors listed in 250.118 should be present to assure all raceways, equipment, etc are grounded.
By Code a metallic conduit ssytem is sufficient. On these systems I'd prefer a conductor or both.
By Code a metallic conduit ssytem is sufficient. On these systems I'd prefer a conductor or both.
and to the grounding electrode(s).. see 250.24(E)
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Exactamundo! It's a circuit conductor that just happens to be grounded. Bond at the service disconnect the same way.
Treat it as you would any other grounded conductor: never re-grounded nor used for bonding, fully insulated, and colored white or gray.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Since you are dealing with an existing install (and by the looks of it more then a year old) the code cycle this was installed under is 05 or older, this makes it acceptable to not have the ground wire (or green wire) run to the separate structure, you can add a ground rod there and bond at the structure. What you are looking to do is get a zero potential between all the parts of the system that could be touched by anyone and have a path that can clear a fault.
scottytoohottie
Member
did you check the phase rotation? maybe someone who worked on the system before you did, hooked up the high leg to the wrong phase or something. i would also check all the electrical parts of the machine to make sure a certain part isnt causing the ground fault. i would toubleshoot the whole system from a to z to be 100 percent of the cause.
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