120 volt receptical from 208 3 phase panel

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Most of the motors and AC equipment that I've seen will run on 208V/240V. Some residential services come from 3 phase transformers. They will run one house on phase A/B, the second house on phase B/C and the third house on phase A/C. So each house would still have 2 hots and a neutral just like a single phase service. Also, only one leg (high leg) of a delta transformer has 240V, the other two legs are 208V. The high leg must be marked or colored orange. Most dryers, water heaters, ranges and ovens also will work on 208V/240V.
 
adrian33773 said:
Also, only one leg (high leg) of a delta transformer has 240V, the other two legs are 208V. The high leg must be marked or colored orange. Most dryers, water heaters, ranges and ovens also will work on 208V/240V.
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A 4 wire delta system will have 240 volt across any two phases, 120 volts between two of the phases and the grounded conductor and the other phase will have 208 volt between itself and the grounded conductor.
 
Thanks Trevor, I stand corrected. I was just checking to see if anybody was awake out there. Actually, I had to brush the dust off my old books. I guess after our brains store so much info it starts to get scrambled a little bit.
 
However, I did see somewhere in the code that the high or wild leg has to be landed in the middle and marked with orange tape. And there is also a 240/480 delta system, which is set-up the same way only the voltages are all double that of the 120/240 delta system. The wild leg is 415V.
 
brian john said:
Upgrade kit, what they supply a 4th conductor?
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No - the neutral bar... You supply the fourth conductor. ;) Often larger panels are shipped with the neutral seperate. You'll see the panel numbers, and all the accessories, like ground bars, and other kits as add-on's.
 
208 neutral

208 neutral

Be careful not to open the neutral or lift it from the neutral bar.
Many circuits may be sharing the neutral of a balanced 3 ph. 4 wire 208 Y.
 
Talked with the site super today, we got the job to wire the "clean room", and the panel I saw the first day is being replaced with one with a main breaker, and it is 3 phase, 4 wire. Thanks to all of you for your input, been at the elect and HVAC business for a while, but this is our first venture into the "commercial" world. I'll be back, I'm sure, with more questions in the future.
 
Just a question, is this government work? You say AF Base, I am thinking Air Force Base. Be careful, just like area 51, many go in, few come out.LOL
 
120/208V 4-wire system

120/208V 4-wire system

Between all three phases you will measure 240 volts. Between to individual phases and ground you will read 120 volts. Between the "High Leg" and ground you will read 208 volts. Be carefull when you lift any ground or nuetral as these are alot of times shared and are tied together at distrubution. We always put our high leg opposit of ground to illimanate confusion if phase rotation is backward. Also you have to watch where the high leg goes so you don't burn anything up that is rated at 120 volts.
 
Hey stray spark, I know what ya mean, I went into the A.F. and it took me 20 years to escape. We are working at the University of Tenn Space Institute. The current space shuttle commander is a grad of UTSI. They still haven't pulled wire to the panel, but we are told it is a 208/240 V 3 phase 4 wire system. We are doing all of the 120/240 V stuff.
 
jrk said:
Between all three phases you will measure 240 volts. Between to individual phases and ground you will read 120 volts. Between the "High Leg" and ground you will read 208 volts. Be carefull when you lift any ground or nuetral as these are alot of times shared and are tied together at distrubution. We always put our high leg opposit of ground to illimanate confusion if phase rotation is backward. Also you have to watch where the high leg goes so you don't burn anything up that is rated at 120 volts.
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Why would the lifting a ground be a problem? The EGC carries no current under normal conditions.
 
jrk said:
A 120/208V sytsem has 2 legs that are 120V to ground and 1 "High" leg that reads 208V to ground but reads 240V betwen any two phases.
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A 120/208Y service is a single phase, three-wire, open wye configuration, which is a modifcation of a three phase, 4-wire system. They are predominantly used where a single phase panel/service is needed in an area where the utility is already operating 208Y/120V system.

Please refer to ANSI C84.1 for a complete listing of standard 60Hz voltage Ratings.
 
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