3 Phase 3 wire to 3 Phase 4 wire

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Peterd1982

New member
Location
Los Angeles, Ca
I am installing a new 3 phase distribution panel and a new 3 phase 200A panel which is fed off of that. The distribution board is a 3 phase 3 wire 240 V. The new 200A panel is a 3 phase 4 wire 240v. I believe this is a delta High Leg to ground. My question is how would I get a neutral?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
If that is a service distribution panel then it must have a neutral. Otherwise, you will have to use a transformer as Trevor stated or feed from another panel.
 

kwired

Electron manager
Location
NE Nebraska
Take some voltage readings. If it is 240 volt corner grounded there is no neutral at all, you must separately derive one if needed.

As mentioned if distribution board is the service equipment, code requires the neutral to be there, if there is one.
 

beanland

Senior Member
Location
Vancouver, WA
3-phase 240V

3-phase 240V

Where is the 240V 3-phase 3-wire delta service coming from? Utilities sometimes provide 240V 3-phase 4-wire but, in general, do not provide ungrounded delta services. If it really is an ungrounded 240V delta service, then you will need that 240V 3-wire delta to 240V 4-wire delta transformer because you will need to derive a grounded neutral. If the utility provides a 4-wire service, just run a neutral.
 

kwired

Electron manager
Location
NE Nebraska
I am installing a new 3 phase distribution panel and a new 3 phase 200A panel which is fed off of that. The distribution board is a 3 phase 3 wire 240 V. The new 200A panel is a 3 phase 4 wire 240v. I believe this is a delta High Leg to ground. My question is how would I get a neutral?

It has to have a neutral if it is a high leg to ground system.

You need to take some measurements and figure out what it is you do have.

If only three incoming conductors and is three phase - the only NEC compliant thing it can be is a corner grounded delta, or possibly an ungrounded system
 
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