Supplying 100 meters?

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11Haze29

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Electrical Engineer
Never did this before so hope you can help. A friend who owns a construction company is looking to build a 100 apartment complex. It will be one large 'L' shape building with 50 apartments on either side. I've done a lot of industrial application but not residential. If we went on the assumption that we could use two 750KVA transformers, centered on each 'leg' of the building, how would you bring in power to each apartment. First, what voltage? A residence would typically be 240/120 single phase. But would you use a single phase transformer, or a three phase transformer and bring in 208/120 single phase to each
apartment. I've seen meter paks with a primary breaker and then up to 24 meter sockets, but do they make them up to 50 sockets. What is typical method to supply an apartment building this size.
 
11Haze29 said:
three phase transformer and bring in 208/120 single phase to each apartment.
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Definitely three phase with 120/208 single phase to each apartment.
11Haze29 said:
I've seen meter paks with a primary breaker and then up to 24 meter sockets, but do they make them up to 50 sockets. What is typical method to supply an apartment building this size.
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Most meter paks that I've seen are modular. You can add as many vertical meter sections as you need, within the permissible load for the ampacity of the bussing.
 
11Haze29 said:
Never did this before so hope you can help. A friend who owns a construction company is looking to build a 100 apartment complex. It will be one large 'L' shape building with 50 apartments on either side. I've done a lot of industrial application but not residential. If we went on the assumption that we could use two 750KVA transformers, centered on each 'leg' of the building, how would you bring in power to each apartment. First, what voltage? A residence would typically be 240/120 single phase. But would you use a single phase transformer, or a three phase transformer and bring in 208/120 single phase to each
apartment. I've seen meter paks with a primary breaker and then up to 24 meter sockets, but do they make them up to 50 sockets. What is typical method to supply an apartment building this size.
Click to expand...
As David said, this will almost certainly be 208/120Y for the service with 120/208 single phase to each unit but this is not certain as this will depend on the POCO and the facilities available. You need a full and correct Article 220 calc. before you do anything this is not something you can just make an educated guess at. Sounds like you need an engineer.
 
Here the POCO would be the 1st deciding factor. After looking at their infrastructure a decision can be made on single phase vs 3 phase and the service points. 100 units here are often broken up into 25-50 unit sections with a service to each. Often the AHJ is involvedf and then info passed along for engineered drawings.
 
Thanks all. Yes, I realize all of this has to be planned in detail and approved. I just wasn't sure if brining in 208/120 single phase to each appartment was the right path. You typically think of a residence as 240/120 but I figured most 240 appliances would also work on 208.
Thanks for all the assistance.
 
11Haze29 said:
Thanks all. Yes, I realize all of this has to be planned in detail and approved. I just wasn't sure if brining in 208/120 single phase to each appartment was the right path. You typically think of a residence as 240/120 but I figured most 240 appliances would also work on 208.
Thanks for all the assistance.
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Most 240 appliances will not operate properly unless they are rated for 208 or 240. Electric stoves and stuff would all need to be rated for 208
 
Definitely check with the utility first. We serve our apartments like that 120/240 single phase because it’s just easier for the developer, electrician, and residents.
 
electrofelon said:
Pretty much all resi appliances are rated for both voltages.
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Yes, but any 240 resistive type appliances take the 25% haircut in capacity. I used to work in an area that had a lot of 208 volt condos. Used to get complaints about it from owners, especially part timers that also had single family homes with 240 volt-often with the same appliances. Electric grills it was especially noticeable. Some items, where we could get 208 elements we would change them such as water heaters. But most appliances you were out of luck. We would also see A/C condensing units that sometimes wouldn't start as they aged.
 
texie said:
Yes, but any 240 resistive type appliances take the 25% haircut in capacity. I used to work in an area that had a lot of 208 volt condos. Used to get complaints about it from owners, especially part timers that also had single family homes with 240 volt-often with the same appliances. Electric grills it was especially noticeable. Some items, where we could get 208 elements we would change them such as water heaters. But most appliances you were out of luck. We would also see A/C condensing units that sometimes wouldn't start as they aged.
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Yes of course, but "208 appliances" are essentially not a thing, that is my point.
 
augie47 said:
208v residential ranges are available..
example: https://www.bestbuy.com/site/frigid...range-stainless-steel/5857605.p?skuId=5857605
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If you look at the spec sheet on the Frigidaire web site it states 240 volts.

I think its kind of risky for manufactures to offer 208 volt only residential appliances since they have no control over what voltage the receptacle its being plugged into is. The only safe way would be for the appliance to have some type of high voltage cutoff.

A 240 volt range or dryer will produce less heat at 208 volts. A 208 volt appliance connected to 240 volt could be a fire hazard.
 
texie said:
AFAIK there is no such thing as true 208 residential appliance.
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Yeah I agree. I remember a while back this topic of apartments on a 120/208 service came up here on the forum and some people said "make sure to get 208 appliances" . I had never heard of such things and did some digging and could not find any. I suppose it is possible someone ordering thousands of these things for a project could make a special factory order but I'm skeptical that happens.
 
texie said:
Interesting. But I think it is a typo. on their site. The manufacturer manual indicates 120/240, 120/208. AFAIK there is no such thing as true 208 residential appliance.
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electrofelon said:
Yeah I agree. I remember a while back this topic of apartments on a 120/208 service came up here on the forum and some people said "make sure to get 208 appliances" . I had never heard of such things and did some digging and could not find any. I suppose it is possible someone ordering thousands of these things for a project could make a special factory order but I'm skeptical that happens.
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Third here..

I can get some 208 elements for water heaters and MAYBE stove elements, but have never been able to order a true 208 appliance unless I get the commercial stuff.
 
Aren't many these appliances marked 240 volts with "usable at 208 volts @ XXXX watts" or similar wordage?

Your water heaters, unit heaters, baseboard heaters or even heat strips for fan coil units will normally be slash marked 208/240, with reduced output rating if used at the lower voltage - with those you just need to size accordingly to the input volts
 
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