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Old 06-02-2012, 11:58 PM   #61
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Concerns re overloading 200 amp service in a 12-unit multi-family


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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?

Yes these exist, but you're looking at several thousand dollars to purchase.

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Old 06-03-2012, 12:03 AM   #62
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Concerns re overloading 200 amp service in a 12-unit multi-family


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Yes these exist, but you're looking at several thousand dollars to purchase.
Thanks much for that...

... I think
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Old 06-03-2012, 02:58 AM   #63
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Concerns re overloading 200 amp service in a 12-unit multi-family


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Well, I’m still a bit confused, inasmuch as other posters have advised that my 200 amp service equals 400 amps @ 120V, or 33.3 amps per unit
.
Have we yet ascertained for sure if it is a 120v service or 220v service ?
No one has said for sure !

I still cant see how 220v can be a single phase service !
As 220v is usually obtained from 2 x phases !

So I am still working on the assumption it is 120v !
Who knows for sure ?
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Old 06-03-2012, 06:17 AM   #64
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Concerns re overloading 200 amp service in a 12-unit multi-family


Single Phase is 120/240v service.
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Old 06-03-2012, 08:28 PM   #65
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Concerns re overloading 200 amp service in a 12-unit multi-family


The 120/240 volt power obtained from the (center tapped) secondary of a single transformer is called single phase. The two hot wires are preferably referred to as legs rather than phases.
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Old 06-03-2012, 09:12 PM   #66
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Concerns re overloading 200 amp service in a 12-unit multi-family


I know this thread is being well covered, and I may have missed it, but I didn't see anyone spell out that it seems like the trouble you have is that the main breaker could trip--All it will take is a warm day and a few people baking pizza for dinner, and you have 12 apartments without power.

If you live on-site this might not be deal breaker, you can throw the main back on and then knock on a few doors asking them to turn off the a/c, or oven for an hour or so, but seems pretty lousy to me on the whole unless you're charging cheap rent.

I'd say it's clear that with 200A you are at best marginal and have been getting lucky. Energy efficient upgrades are great, but with the potential for 12 window air conditioners and 3 electric ovens, you're pushing your luck.
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Old 06-03-2012, 11:32 PM   #67
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Concerns re overloading 200 amp service in a 12-unit multi-family


I think most people agree that an upgrade is recommendded !
But I also see that the owner is trying to canvas all options first,
As an upgrade will not be cheap.

But I am concerned about the legal liability side of things
if there is an overload and subsiquent damage or even fire,
a real possibility, the first thing they will say is "The electrical
system was not sufficent for the expected damand"
Then he could be held liable.

Is this not a realistic concern ?
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Old 06-04-2012, 08:43 AM   #68
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Concerns re overloading 200 amp service in a 12-unit multi-family


I do not see fire as a concern.

Should tenants be baking pizza and running air conditioners causing the main breaker to trip, none of the individual subservices to the apartments will be anywhere near overloaded. Only upstream of the panel down in the basement where the individual subservices branch off, on out to the utility pole could possibly be affected.

The OP should verify that the main feeder wires are indeed sized for 200 amps. (or 100 amps for each of two cables from the meter going to respective panels with 100 amp main breakers and with six 60 amp breakers serving six apartments respectively.) The overhead service wires hang in free air and do not have to be as fat as wires in conduits or cables.
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Last edited by AllanJ; 06-04-2012 at 08:51 AM.
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Old 06-04-2012, 11:55 PM   #69
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Concerns re overloading 200 amp service in a 12-unit multi-family


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I know this thread is being well covered, and I may have missed it, but I didn't see anyone spell out that it seems like the trouble you have is that the main breaker could trip--All it will take is a warm day and a few people baking pizza for dinner, and you have 12 apartments without power.

If you live on-site this might not be deal breaker, you can throw the main back on and then knock on a few doors asking them to turn off the a/c, or oven for an hour or so, but seems pretty lousy to me on the whole unless you're charging cheap rent.

I'd say it's clear that with 200A you are at best marginal and have been getting lucky. Energy efficient upgrades are great, but with the potential for 12 window air conditioners and 3 electric ovens, you're pushing your luck.
I would have agreed with you entirely a few weeks ago, and it was these concerns which brought me to this board.

Of course, at the time I’d assumed that my 200 amp service was 200 amps at 120V rather than 240V (which I now believe to be the case).

I also assumed that window air conditioners consumed between 1,200 and 1,500 watts. I now know that the 5,200 BTU machines consume 486 watts while the 6,000 BTU machines consume 561 watts. (I only permit machines 6,000 BTUs or smaller with EERs of 10.7 or better).

Because electricity rates have been skyrocketing I had not realized how effective my efforts to reduce consumption have been. I now see that we are using 50% to 60% less electricity than we did fifteen years ago when I bought the building (in spite of having five air conditioners last summer compared to only one in 1997). Aside from reducing annual consumption I have reduced the potential peak demand by 25% by eliminating three gas stoves and converting to efficient lighting.

The elimination of the stoves may or may not help reduce the risk of overloading (since my tenants… many of them students… are more likely to use their microwaves) but the lighting is significant. It would not be unusual for tenants to have most of their lights on in the evening and of course the hallway lights are on around the clock. My lighting retrofit has reduced the maximum load from about 10,000 watts to about 2,500 watts, and when finished I’ll be down to about 1,500 watts. That’s a reduction of 85% and represents the elimination of about 62 amps of potential load. Put another way, 200 light bulbs at 6 watts is the equivalent of twenty 60-watt bulbs, which is what we might find in a typical three-bedroom bungalow.

Finally, although I have been downloading my hourly consumption into a spreadsheet for the past 30 months this was primarily intended to allow me to track costs, and I was not sure how to use the data to correlate usage to peak load (and recognize that since the data represents average consumption over an hour it cannot be relied upon to accurately reflect peak loads). Nonetheless, the maximum consumption we’ve seen in any summer period was 6.75 KWH, which is less than 60 amps. That occurred on a hot summer evening between 9:00 pm and 10:00 pm when I presume everyone cranked up the air conditioners in the bedrooms. Assuming that the maximum load during the hour was not more than 150% of the average we can assume that the peak demand never exceeded 23% of the system’s capacity. (For what it’s worth, notwithstanding the five air conditioners which were installed last summer our highest consumption occurs in the winter, when more lights are on, more tenants are home, and more cooking is done with the stoves. Our highest usage over 30 months was in December at 8.62 KWH).

I appreciate everyone’s comments and concerns, but unless I have committed some bad math it seems to me that I am some distance from overloading this system.
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Old 06-05-2012, 12:58 AM   #70
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Concerns re overloading 200 amp service in a 12-unit multi-family


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Originally Posted by dmxtothemax View Post
I think most people agree that an upgrade is recommendded !
But I also see that the owner is trying to canvas all options first,
As an upgrade will not be cheap.

But I am concerned about the legal liability side of things
if there is an overload and subsiquent damage or even fire,
a real possibility, the first thing they will say is "The electrical
system was not sufficent for the expected damand"
Then he could be held liable.

Is this not a realistic concern ?
I do not feel that an upgrade to 400 amps is viable. Indeed, our utility has been ordered to reduce consumption by 5% or face financial penalties, so they are likely to put up as many obstacles as possible.

In any case, as noted in the above post I am increasingly of the opinion that an upgrade is unnecessary. In any case, I can easily reduce the potential maximum load by about 10% by converting three more electric stoves to gas (and I continue to retrofit the lighting, which will remove another KW of potential load when finished in a few weeks).

I doubt that legal liability is a concern. If I am not in compliance with Code (and I am not certain that I am not in Code compliance) it is because the methodology which I would need to use to calculate load would require that I allow for six electric stoves which no longer exist (having been replaced by gas stoves).

Because Code permits us to use a factor of 40% (approximately, depending upon the jurisdiction) for some loads there is no guarantee that in unusual circumstances the actual load could not exceed this and overload the system. Indeed, most of the apartments are Code-compliant, however if a tenant has enough gadgets and turned them on all at once they could trip the breaker in the apartment’s subpanel (if they also have an electric stove).

So yes, my system could be overwhelmed if everyone turned on enough appliances at the same time. However, I feel that this is an unlikely scenario in a twelve-unit building, given that it would require a spike five times higher than the highest average load recorded in the past thirty months, and I doubt that such a spike could be considered “expected demand”.

In order for a claimant to realize any significant award there needs to be gross negligence or careless indifference. It is worth noting that the utility’s concern with service upgrades is that their grid (antiquated in this part of town) will be overloaded. In this context, my efforts to improve the efficiency of the building are arguably a more responsible approach to energy management, and my investment in these efforts has been considerable, so I doubt that anyone would accuse me of careless indifference.

Finally, as I noted in a previous post, when I was considering upgrading to a 400 amp service the utility sent someone over to discuss the viability of such an upgrade. He said that he could not determine the need for an upgrade without doing a detailed load calculation, however he did visit the utility room, he did see all of the panels and breakers, but he did not express concern. Having given the property his tacit approval we can presume that the utility might be a party to any liability claim, no?
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Old 06-05-2012, 01:00 AM   #71
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Concerns re overloading 200 amp service in a 12-unit multi-family


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I do not see fire as a concern.

Should tenants be baking pizza and running air conditioners causing the main breaker to trip, none of the individual subservices to the apartments will be anywhere near overloaded. Only upstream of the panel down in the basement where the individual subservices branch off, on out to the utility pole could possibly be affected.

The OP should verify that the main feeder wires are indeed sized for 200 amps. (or 100 amps for each of two cables from the meter going to respective panels with 100 amp main breakers and with six 60 amp breakers serving six apartments respectively.) The overhead service wires hang in free air and do not have to be as fat as wires in conduits or cables.
Thanks. I will be visiting the property tomorrow and will take some photos.
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Old 06-05-2012, 11:46 PM   #72
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Concerns re overloading 200 amp service in a 12-unit multi-family


I'd just like to say thanks for replying and keeping in touch with this thread. So many members post once or twice and never reply again.
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Old 06-07-2012, 01:30 PM   #73
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Concerns re overloading 200 amp service in a 12-unit multi-family


Guess I was wrong.
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Old 06-07-2012, 01:50 PM   #74
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Concerns re overloading 200 amp service in a 12-unit multi-family


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Guess I was wrong.
Don't worry, I'll be back. Unfortunately I've been too busy to get to the property in question.

Yesterday I was dealing with an electrician on another matter... a swimming pool pump which shuts off every time it rains, and has done so for years. So far we have replaced every component in this outdoor circuit... the main breaker, the wiring, the GFI outlet, the weatherproof box, and the pump itself. Yesterday's electrician claimed that we had a defective (that is, another defective) GFI outlet, so he replaced it for $435. An hour later it started to rain and the new GFI tripped and would not reset. When we called the electrician back he explained that the purpose of a GFI was to trip whenever it rained.

Sorry for the thread drift. I will give up on the pool pump and return to the perplexing issues at the 12-plex.

(Likely no need to reply to the pool pump problem... five electricians have tried and failed... and I would not want this to drift off-topic).
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Old 06-07-2012, 08:27 PM   #75
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Concerns re overloading 200 amp service in a 12-unit multi-family


From the numbers you gave and seeing that you have reduced lighting power use and taken away some electric stoves, it looks to me as if you can safely allow each tenant one 6000 BTU air conditioner.

You can take applications for this summer and see how things go, power usage wise.

If not all tenants put in air conditioners and pay you the energy surcharge you specify, you should still collect data and make allowance for each apartment to have one air conditioner before granting permission for second air conditioners.

"Demand" refers to the number of amperes (not kilowatt hours) being drawn at any moment. If you do upgrade your service it is possible that you would have to go into a different rate category that includes a "demand charge" based on the highest spike in demand each month (or maybe the highest 4 or 5 spikes, one each week) even if the spike occurred for only fifteen seconds. The demand charge is in addition to the other charges on your bill.

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Last edited by AllanJ; 06-07-2012 at 08:35 PM.
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