If you have a 3 phase, 120/240V w/208V high leg, meter base feeding a 3 phase panel and you take out the 3 phase panel and replace it with a single phase panel and cap off the 208 V leg, will the power companys watt hour meter still record the electric usage correctlly? I dont see how it can, and would this be a code violation? Thanks.
3 phase to single phase
- Thread starter mrhanky
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david
Senior Member
- Location
- Pennsylvania
Re: 3 phase to single phase
No power Co. is going to allow you to use a three phase meter enclosure on a single phase service.
110.3 Examination, Identification, Installation, and Use of Equipment.
(B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.
No power Co. is going to allow you to use a three phase meter enclosure on a single phase service.
110.3 Examination, Identification, Installation, and Use of Equipment.
(B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.
charlie
Senior Member
- Location
- Indianapolis
Re: 3 phase to single phase
Yes, the meter will still record correctly. It would be no different than having just single phas load running on a 120/240 volt, 3 phase, 4 wire service. I don't think the electric utility would allow the three phase metering and the additional transformer(s) to remain and waste power.
Yes, the meter will still record correctly. It would be no different than having just single phas load running on a 120/240 volt, 3 phase, 4 wire service. I don't think the electric utility would allow the three phase metering and the additional transformer(s) to remain and waste power.
bonding jumper
Senior Member
Re: 3 phase to single phase
Most utility companies install three phase meters these days. They do this reguardless if your service is going to be single phase or three phase. But I don't reccomend doing what your are doing. First of all, why? three phase power is more efficient than single phase. What your doing is unbalancing your three phase power to make it less efficient. Your also gonna create a current across your neutral, by unbalancing the phases. That is the lost energy that u will be wasting. U should call the utility company and have them change your service to single phase, they generally do this with no charge involved. But I am worried about why u are doing this? Did your overall load in your house change? If it did not, and you are going to use one less leg for the house load, you will be increasing the ampacity of the other two legs you are using because you have eliminated one leg. That could be dangerous based on how they are sized.
[ August 11, 2003, 11:21 AM: Message edited by: bonding jumper ]
Most utility companies install three phase meters these days. They do this reguardless if your service is going to be single phase or three phase. But I don't reccomend doing what your are doing. First of all, why? three phase power is more efficient than single phase. What your doing is unbalancing your three phase power to make it less efficient. Your also gonna create a current across your neutral, by unbalancing the phases. That is the lost energy that u will be wasting. U should call the utility company and have them change your service to single phase, they generally do this with no charge involved. But I am worried about why u are doing this? Did your overall load in your house change? If it did not, and you are going to use one less leg for the house load, you will be increasing the ampacity of the other two legs you are using because you have eliminated one leg. That could be dangerous based on how they are sized.
[ August 11, 2003, 11:21 AM: Message edited by: bonding jumper ]
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: 3 phase to single phase
A 3 element watthour meter is basically 3 single phase meters on a common shaft, so this type of meter will absolutely work.
A 2-1/2 element watthour meter is basically 2 single phase meters with common voltage connections, so this type of meter will work correctly if all of the 3 phase voltages remain balanced.
[ August 11, 2003, 11:29 AM: Message edited by: jim dungar ]
A 3 element watthour meter is basically 3 single phase meters on a common shaft, so this type of meter will absolutely work.
A 2-1/2 element watthour meter is basically 2 single phase meters with common voltage connections, so this type of meter will work correctly if all of the 3 phase voltages remain balanced.
[ August 11, 2003, 11:29 AM: Message edited by: jim dungar ]
- Location
- Illinois
- Occupation
- retired electrician
Re: 3 phase to single phase
bonding jumper,
This is a 120/240 3 phase, 4 wire, wild leg delta system. The third phase has nothing to do with the neutral current(line to neutral loads are not served by this phase as it has a voltage of 208 to the grounded conductor), and there is no balance problem because the 120/240 volt single phase loads are connected on a single transformer. A second, smaller, transformer connected open delta would normally be used to supply the third phase.
Don
bonding jumper,
This is a 120/240 3 phase, 4 wire, wild leg delta system. The third phase has nothing to do with the neutral current(line to neutral loads are not served by this phase as it has a voltage of 208 to the grounded conductor), and there is no balance problem because the 120/240 volt single phase loads are connected on a single transformer. A second, smaller, transformer connected open delta would normally be used to supply the third phase.
Don
pierre
Senior Member
- Location
- Westchester County, New York
Re: 3 phase to single phase
What is the purpose of a service of this type? Could one use the 208v to ground leg for any useful purpose? I would be surprised if this were for a residence.
Mrhanky
Why don't you install a 120/240v subpanel?
Pierre
What is the purpose of a service of this type? Could one use the 208v to ground leg for any useful purpose? I would be surprised if this were for a residence.
Mrhanky
Why don't you install a 120/240v subpanel?
Pierre
Re: 3 phase to single phase
In older days some houses were furnished with a 3 phase AC unit and single phase everything else. I have even seen what is called a Delta breaker installed in lieu of a 3 phase panel which is illegal. This breaker had a lug for the high leg input and a lug for the high leg output plus the two phases which it took off the busbar. Sort of like a 240 volt switched neutral breaker which is used in gasoline pumping stations. I also have seen where some folks send a ground and a neutral and the high leg to a cook stove and a dryer and a water heater which, if fed with a straight 240 volt breaker, may not be illegal.
In older days some houses were furnished with a 3 phase AC unit and single phase everything else. I have even seen what is called a Delta breaker installed in lieu of a 3 phase panel which is illegal. This breaker had a lug for the high leg input and a lug for the high leg output plus the two phases which it took off the busbar. Sort of like a 240 volt switched neutral breaker which is used in gasoline pumping stations. I also have seen where some folks send a ground and a neutral and the high leg to a cook stove and a dryer and a water heater which, if fed with a straight 240 volt breaker, may not be illegal.
Re: 3 phase to single phase
Irollo, just curious, where are you at, and when was this, that houses were fed with delta services? BTW, delta breakers had to be legal when this took place.
Roger
[ August 12, 2003, 08:35 PM: Message edited by: roger ]
Irollo, just curious, where are you at, and when was this, that houses were fed with delta services? BTW, delta breakers had to be legal when this took place.
Roger
[ August 12, 2003, 08:35 PM: Message edited by: roger ]
pierre
Senior Member
- Location
- Westchester County, New York
Re: 3 phase to single phase
Ignorance is bliss!
It amazes me what one (me) does not know, and it is cool to learn what there is 'out' there. This is definitely one of the reasons for this forum.
Thanks!
Pierre
Ignorance is bliss!
It amazes me what one (me) does not know, and it is cool to learn what there is 'out' there. This is definitely one of the reasons for this forum.
Thanks!
Pierre
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