120/240, three-phase. w/ neutral
- Thread starter peterelec
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peter d
Senior Member
- Location
- New England
Re: 120/240, three-phase. w/ neutral
Was this a former manufacturing building/mill that was converted into condos?
I find it highly unusual that a condo building would have that a 4 wire 3phase 120/240 volt service. Weird.
Was this a former manufacturing building/mill that was converted into condos?
I find it highly unusual that a condo building would have that a 4 wire 3phase 120/240 volt service. Weird.
charlie
Senior Member
- Location
- Indianapolis
Re: 120/240, three-phase. w/ neutral
I would assume that this is an electric utility owned transformer bank, is it? If it is, I would ask them if they would replace it with a 208 wye bank. If you own it, determine the calculated 3? load and subtract that from the 3? bank kVA to see what you have left for the 1? loads. Take the calculated 1? loads and spread them at the rate of 1/3 on each of the smaller transformers and 2/3 on the larger transformer (the one with the center tap ground). If you haven't overloaded any of the transformers, you are good to go.
I would assume that this is an electric utility owned transformer bank, is it? If it is, I would ask them if they would replace it with a 208 wye bank. If you own it, determine the calculated 3? load and subtract that from the 3? bank kVA to see what you have left for the 1? loads. Take the calculated 1? loads and spread them at the rate of 1/3 on each of the smaller transformers and 2/3 on the larger transformer (the one with the center tap ground). If you haven't overloaded any of the transformers, you are good to go.
Re: 120/240, three-phase. w/ neutral
It is utility owned and we are renovating an existing condo building so it is not really practical to switch things out. Thank you for all your answers, one more question, I understand the calculation at the xfmr but if I am at an 800A, three phase meter stack, how do I calculate the amps on that feeder, am I looking too much into this. Is it the same calc: (VA)/((240)(1.73))..thanks again.
It is utility owned and we are renovating an existing condo building so it is not really practical to switch things out. Thank you for all your answers, one more question, I understand the calculation at the xfmr but if I am at an 800A, three phase meter stack, how do I calculate the amps on that feeder, am I looking too much into this. Is it the same calc: (VA)/((240)(1.73))..thanks again.
charlie
Senior Member
- Location
- Indianapolis
Re: 120/240, three-phase. w/ neutral
If by using the term "three phase meter stack", you are talking about services to condos with residential services and you are using meter centers, it will not work. A three phase meter center is used to provide single phase 208 to apartments and condos. It will not work on 120/240, 3?, 4w since this configuration has a high ? and you will not be able to balance the loads.
You can only install 1? meter centers to serve the condos and then use the 3? for the house panelboard with the 3? used for elevators and other 3? loads with the 1? portion for the common lighting loads.
If by using the term "three phase meter stack", you are talking about services to condos with residential services and you are using meter centers, it will not work. A three phase meter center is used to provide single phase 208 to apartments and condos. It will not work on 120/240, 3?, 4w since this configuration has a high ? and you will not be able to balance the loads.
You can only install 1? meter centers to serve the condos and then use the 3? for the house panelboard with the 3? used for elevators and other 3? loads with the 1? portion for the common lighting loads.
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