Concerns Re Overloading 200 Amp Service In A 12-unit Multi-family - Electrical - Page 4 - DIY Chatroom Home Improvement Forum

 DIY Chatroom Home Improvement Forum Concerns re overloading 200 amp service in a 12-unit multi-family
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05-28-2012, 11:54 PM   #46
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If it is indeed a single phase meter,
then it could be a single phase service,
That means 120v at 200 a.
So if that is the case,
then it is indeed limited to 16a per apartment.
Simple maths 200a / 12 units ? that 16.6 amps per unit.
Thats 1992 watts at 120v.

A small window A/C unit would use most of that.

05-28-2012, 11:58 PM   #47

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Quote:
 Originally Posted by dmxtothemax If it is indeed a single phase meter, then it could be a single phase service, That means 120v at 200 a. So if that is the case, then it is indeed limited to 16a per apartment. Simple maths 200a / 12 units ? that 16.6 amps per unit. Thats 1992 watts at 120v. A small window A/C unit would use most of that.
A single phase service doesn't mean a 120V service.

05-29-2012, 12:18 AM   #48
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Quote:
 Originally Posted by k_buz A single phase service doesn't mean a 120V service.
Ummm... I would have assumed that so long as my 240V stoves work as intended then there is 240V coming into the panel, no?

05-29-2012, 01:05 AM   #49

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Quote:
 Originally Posted by apartment_guy Ummm... I would have assumed that so long as my 240V stoves work as intended then there is 240V coming into the panel, no?
I was responding to what DMX posted
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Answers based on the National Electric Code. Always check local amendments.

 05-29-2012, 05:26 AM #50 Member   Join Date: Nov 2007 Location: Nashua, NH, USA Posts: 7,966 Rewards Points: 1,538 What are the ratings of (all of) the "main breakers" you have? Excluding the bank of master 60 amp or so breakers for each individual apartment Upgrading you to 3 phase is a desire, not a need. While the load on the three primary lines should be balanced, it is not difficult to change the taps off the primary lines for other pole transformers on the street to different phases to accomplish this while you still have just one transformer providing you with single phase service. By name, a 200 amp 120/240 volt service allows 200 amps @ 240 volts. A 200 amp 3 phase 120/208 volt service would allow 200 amps' draw on each leg, or three allotments of 120 volts @ 200 amps. It is not proper to suddenly change you over from 120/240 single phase to 120/208 volt (symmetric neutral; wye; star) 3 phase since you may have equipment that does not work on 120/208 or 208 only. Also a 120/240 volt (delta) 3 phase service will not accomplish anything because all the individual apartments with 120/240 volt single phase must be fed off the same two of the three lines in the 3 phase system. It would require extensive rewiring to put the 240 volt only loads on the otherwise unused third leg whose hot to neutral voltage is somewhat higher than 120 volts. __________________ The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit. Last edited by AllanJ; 05-29-2012 at 05:43 AM.
 05-29-2012, 06:36 PM #51 Member     Join Date: Oct 2010 Location: Brisbane, Australia. Posts: 4,273 Rewards Points: 5,504 I would not think that a single phase service is 220/240. Whilst it is technically possable. You would not be able to use any 120v appliances, Unless there is an on site transformer to split the phase. Or am I missing something ?
05-29-2012, 07:38 PM   #52
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Quote:
 Originally Posted by k_buz I was responding to what DMX posted
I understand that.

In replying to your post I was hoping that my hunch/guess would be confirmed insofar as you seem to have a grasp of things.

I do not want to offend DMX, but as you may be aware in Australia the water swirls down the drain in the wrong direction, so I can't even imagine what their electricity does

05-29-2012, 08:19 PM   #53
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Quote:
 Originally Posted by AllanJ What are the ratings of (all of) the "main breakers" you have? Excluding the bank of master 60 amp or so breakers for each individual apartment Upgrading you to 3 phase is a desire, not a need. While the load on the three primary lines should be balanced, it is not difficult to change the taps off the primary lines for other pole transformers on the street to different phases to accomplish this while you still have just one transformer providing you with single phase service. By name, a 200 amp 120/240 volt service allows 200 amps @ 240 volts. A 200 amp 3 phase 120/208 volt service would allow 200 amps' draw on each leg, or three allotments of 120 volts @ 200 amps. It is not proper to suddenly change you over from 120/240 single phase to 120/208 volt (symmetric neutral; wye; star) 3 phase since you may have equipment that does not work on 120/208 or 208 only. Also a 120/240 volt (delta) 3 phase service will not accomplish anything because all the individual apartments with 120/240 volt single phase must be fed off the same two of the three lines in the 3 phase system. It would require extensive rewiring to put the 240 volt only loads on the otherwise unused third leg whose hot to neutral voltage is somewhat higher than 120 volts.
I will attempt an inventory on my next visit (which may not be for a couple of days).

I am somewhat familiar with the load calculations for single-family homes, but am not sure how relevant they would be in the case of this type of building.

I am aware, for example, that I have dedicated 45 amps (three 15 amp circuits) to devices with loads that could likely be measured in milliamps.... the fire alarm panel requires a separate circuit, the smoke detectors require a seperate curcuit, and the exit signs require a separate circuit... the latter are fitted with LEDs and consume perhaps 20 watts in total.

 05-29-2012, 09:06 PM #54 Member   Join Date: Nov 2007 Location: Nashua, NH, USA Posts: 7,966 Rewards Points: 1,538 The fact you have three 15 amp circuits dedicated to common area and also the fact you use energy efficient lighting lighting does not affect the load calculatoion. It's the designated wattage per square foot and wattages of various appliances that go into the calculations. The difference between a single family building and a multifamily building is that for the multifamily building the wattage totals for some categories of loads may be multiplied by a factor less than one to take into account not everyone turning on their televisions or vacuum cleaners or stoves at the ame time. But air conditioners (and space heaters) are assumed to be all on at the same time so you do not cut down their total wattage for the load calculations by multiplying by a factor less than one. __________________ The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.
05-29-2012, 10:21 PM   #55
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Quote:
 Originally Posted by AllanJ The fact you have three 15 amp circuits dedicated to common area and also the fact you use energy efficient lighting lighting does not affect the load calculatoion. It's the designated wattage per square foot and wattages of various appliances that go into the calculations. The difference between a single family building and a multifamily building is that for the multifamily building the wattage totals for some categories of loads may be multiplied by a factor less than one to take into account not everyone turning on their televisions or vacuum cleaners or stoves at the ame time. But air conditioners (and space heaters) are assumed to be all on at the same time so you do not cut down their total wattage for the load calculations by multiplying by a factor less than one.
Yes... and that is what brought me to this forum in the first place. That is, there is a disconnect between Code and reality.

i expect that window air conditioners... since they are not permanent installations... are not recognized by Code except to the extent that they are included in the 3 watts per square foot requirement... and even then we would only have to account for 40% of their potential load (depending upon the jurisdiction) notwithstanding that it is highly likely that they will all be running at the same time. As I have observed in crunching my numbers it seems that between 9:00 pm and 10:00 pm most of my tenants go into their bedrooms to turn on the air conditioners. This is good, of course, as this is the time of day (or night) when other loads are at a minimum.

On the other hand, it seems that Code requires that I allocated 40 amps each for my gas stoves. That is, unless I misunderstand there is a Code requirement (here in Ontario) that every kitchen be equipped with a 40 amp stove circuit, even if the kitchen has a gas stove. When I bought the building there were eight units with electric stoves and four with oversized Easy Bake Ovens (by which I mean those two-burner stoves that run on 120V).

I had an electrician install proper 240V stoves to replace three of the Easy Bakes, at the same time taking out six of the existing 240V stoves and replacing them with gas stoves. The net result in practical terms was the elimination of three 240V stoves, but the net result in the context of Code was the addtition of three 240V stoves (which almost certainly pushed my beyond the capacity of my service). That is, notwithstanding that there are no longer electric stoves in six of those apartments Code requires that my service provides for electric stoves in those apartments.

At the risk of belaboring the point, I've reduced the consumption at this property by 50% to 60% in spite of the addition of five air conditoners, and if necessary can likely cut anothe 10%.

FWIW, my wife dug up our own electrical bills (she handles the finances for our home while I deal with three rental properties) and I see that we consume six times as much electricity as is consumed by one of my aprtments (that is, 150 to 175 KW per month). And we could easily get by with a 100 amp service.

In any case, a couple of days ago I reminded all the tenants that they needed to discuss with me before installing any air conditioners, and notwithstanding that we have had three mini heat waves no additional requests have been made.

So long as Code allows that only 40% of some loads need be considered when calculating service sizes there is no assurance that the electrical service in a Code-compliant building could not be overloaded if everyone plugged in everything at once. But it would take a freak occurance.

Similarly, I think that it would take a freak occurance for the system in this building to be overloaded, notwithstanding that my service is arguably inadequate as defined by Code.

Last edited by apartment_guy; 05-29-2012 at 11:49 PM.

 05-29-2012, 10:41 PM #56 retired elect/hvac/plumb     Join Date: Jan 2010 Location: south east of omaha/The island of misfit contractors Posts: 2,921 Rewards Points: 2,020 What are your major loads for each apartment,are you running gas for hot water/cooking and heat? __________________ "facts" have no relevance to this discusion Posting from a concrete bunker under a non descript barn
05-29-2012, 11:16 PM   #57
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Quote:
 Originally Posted by plummen What are your major loads for each apartment,are you running gas for hot water/cooking and heat?
Heating is gas boiler, hot water is gas, laundry room (2 dryers) are gas.

Most stoves are gas.

With respect to Code, our biggest load would be the (mostly phantom) stoves, inasmuch as it seems that Code assumes that every apartment has an electric stove.

In real terms, it is difficult to identify the large loads inasmuch as average consumption is less than 6 KWH per unit, per day.

 05-30-2012, 06:31 AM #58 Member   Join Date: Nov 2007 Location: Nashua, NH, USA Posts: 7,966 Rewards Points: 1,538 Remember that at this time, load calculations are for your private use only. Currently you are grandfathered and you can continue to estimate what the total building load will be using any method you wish (including reality based methods). The code based load calculations would be formalized only if and when you plan to upgrade the service and/or make additions that require bringing everything up to code. But going though the motions of calculating load per the code now will at least give you an idea of how far you are off if you foresee an upgrade in the distant future. You only need to realize that the greater the total load you permit (the greater number of and higher wattage for air conditioners you okay one at a time) the greater the chance of a freak occurrence of tripping the main breaker. Are you sure that the formal (CEC) load calculations need to include an electric stove in an apartment with a gas stove? Yes I would impose a rent surcharge or rent increase at the moment I approve each new air conditioner. The tenant can then change his mind and not get an AC. Tenants who already have air conditioners will have to go through the normal rent increase process, such as at lease renewal, before additional money can be collected to cover the cost of power for their AC. __________________ The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit. Last edited by AllanJ; 05-30-2012 at 06:50 AM.
06-02-2012, 08:57 PM   #59
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 Originally Posted by andrew79 a decent clamp on will cost you a few bucks, around \$100 or so, but it will also function as a multimeter and being as you have your own building it's not an unwise investment. You'll get years of use out of it. Fluke makes a decent "fork" style one but it's a little pricey. here's one at home depot that would work for you, i prefer cat IV but this will work just fine for your application. http://www.homedepot.ca/product/clam...cat-iii/930198 if your really nervous about it i can send you my email, i'm in toronto as well and can give you some better instructions.
Thanks for that.

I headed over the HD today to pick one of these up, but the sales guy says that will only record the load in real time. That is, I was looking for a meter which I could leave attached and which would record and retain in memory the peak load over a period of days or weeks (or months).

Does such a thing exist?

06-02-2012, 09:08 PM   #60
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Quote:
 Originally Posted by apartment_guy I understand that. In replying to your post I was hoping that my hunch/guess would be confirmed insofar as you seem to have a grasp of things. I do not want to offend DMX, but as you may be aware in Australia the water swirls down the drain in the wrong direction, so I can't even imagine what their electricity does
Electricity is electricity no matter where you are !

Amps is still amps, volts is still volts, etc etc
The only difference is how you set up your systems to distribute it .
We dont use split supplies here, its three phase or single phase.
But because we use a higher voltage here 240 instead of 120,
so we can get enough power to a household with only 1 phase.

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