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#194542 - 06/09/10 06:42 PM Demand Meter Help
twh Offline
Member

Registered: 03/11/04
Posts: 898
Loc: Regina, Sask.
A landlord has a commercial building with a demand meter for the entire building. One tenant has a separate, customer owned demand meter, which the landlord is to read and bill the tenant for the tenants usage. The meter is electronic.

How do you read and reset a demand meter?

Another tenant, a tanning salon, wants to install a meter for their own power, too. They don't want to use a demand meter.

Is it worthwhile insisting that the second tenant install a demand meter?

Off topic, the tanning salon had an electrician install current transformers on their feeders. They are donut style with two wires out of each ct. The wires end in a box awaiting connection to a meter. The wires are taped in pairs and the ends aren't visible and may not be shorted. If they aren't shorted, what kind of voltage would be on the wires if the load is a 100 or 200 amps?

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#194544 - 06/09/10 06:59 PM Re: Demand Meter Help [Re: twh]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
TWH:

Without knowing what type of electronic submeters/check meter you have, explaining the reset is difficult.

One brand (E-Mon): Inside of door has a reset button for KWHr. and KW (Demand)

The tanning salon NOT wanting a demand meter tells me that he knows he will save $$$.

You can google 'E-Mon' for more info on their units, both KWHr & KWHr/KW. They are relatively easy units to install, read & reset. Also, good ol' Square D has a very similar unit.


Not having a demand meter on the 'submeter' means the owner foots the demand charges.
_________________________
John

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#194545 - 06/09/10 07:20 PM Re: Demand Meter Help [Re: twh]
mxslick Offline
Member

Registered: 10/24/04
Posts: 785
Loc: Atomic City, ID USA
Originally Posted By: twh
A landlord has a commercial building with a demand meter for the entire building. One tenant has a separate, customer owned demand meter, which the landlord is to read and bill the tenant for the tenants usage. The meter is electronic.

How do you read and reset a demand meter?

Another tenant, a tanning salon, wants to install a meter for their own power, too. They don't want to use a demand meter.

Is it worthwhile insisting that the second tenant install a demand meter?

Off topic, the tanning salon had an electrician install current transformers on their feeders. They are donut style with two wires out of each ct. The wires end in a box awaiting connection to a meter. The wires are taped in pairs and the ends aren't visible and may not be shorted. If they aren't shorted, what kind of voltage would be on the wires if the load is a 100 or 200 amps?


I hope those wires are shorted at the CT end..otherwise you could see thousands of volts and the CT's themselves would probably explode! Make absolute sure that those leads are shorted and DO NOT unshort or disconnect them with power on or you could be shocked or worse.

The emon-demon is the most popular add-on demand meter and is a good idea for your application.

As for the electronic meter, there is a button or lever on the cover glass that if pressed/lifted, will scroll the meter display. If total usage was programmed into the access options you can read total demand. However, you can not usually reset the usage from that button/lever. Depends on meter type and who programmed it.

I have a pair of ABB electronic meters that I need to get reprogrammed but so far can't find anyone with software or willing to do it.
_________________________
Stupid should be painful.

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#194561 - 06/10/10 06:14 PM Re: Demand Meter Help [Re: mxslick]
Tesla Offline
Member

Registered: 06/16/04
Posts: 1280
Loc: Sacramento, CA
The tanning dude knows that he's the Demanding Type.

Demand meters hit your wallet because the Poco is zapping you for the surge in demand that you trigger in a tanning booth -- while not really using it all that much through the day.

If the tanner was burning the watts rather steady through the day then the flat use curve would make the Poco happy. As it stands, the Poco has to keep extra rotating reserve power spooled up at all times to maintain voltage and frequency just due to demanding customers like the tanner.

Thus the Demand Meter was born.

Unless the landlord is a moron, he will insist that the tanner be metered for demand.

( Demand meters charge super pricing for peak kilowatts consumed as against total kilowatts consumed.)
_________________________
Tesla

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#194563 - 06/10/10 06:31 PM Re: Demand Meter Help [Re: Tesla]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
Yes, Tesla you jogged my memory. Back when I did meter reading & billing of the submeters, one utility had 3 demand rates. Peak, Off-peak & intermediate.

The peak rate was about 4 to 5 times the off-peak rate.

That was all within a large industrial park, with 7.2KV, and multiple 480 volt utility services. If I remember, think it was about 35-45 E-mon D-mon units.
_________________________
John

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#194573 - 06/11/10 10:49 AM Re: Demand Meter Help [Re: HotLine1]
mikesh Offline
Member

Registered: 06/07/06
Posts: 614
Loc: Victoria, BC, Canada
I am wondering if we are speaking different terms here.
A demand meter is not always related to different billing rates but obviously has the ability to record highest rates of consumption.
In areas with flat billing or tiered rates the demand is a record of highest peak loading. This number can give you the spare capacity of your service equipment to add load a code calculation would not allow.
How often do we install a big service in a building only to discover that there was never a day where the service was loaded even close to its rating. With demand records it is possible to add load to the recorded demand.
For example you have an 800 amp service and the code calculations shows there is no spare capacity to say add a swimming pool heater or hot tub or another suite etc. You go to the utility and ask for the peak demand over the past 12 months and discover that the service was never loaded beyond say 400 amps so you discover the service has a spare 240 amps of unused capacity. (80% of 800 is 640 amps continuous load capacity)
The other meter type for flat rate billing is a consumption meter. They just record usage but never the peaks or valleys. You get a bill for kilowatts used over time but you would never know if it was used in 3 days or over the month. Sure you know the meter is read on date 1 and on date 2 and the difference is what you used but you were home for only 6 days with the heat on high and guests in the house. the other 24 days you were in Hawaii with the heat on low and the water tank shut off etc. The meter justs spins fast when you were home and barely moves when you were away. The bill just says X kilowatts over the billing period not when you used it and not the peak consumption.
So Demand meters just have a feature to record the peak. old mechanical meters had a red dial that got pushed every peak until it records the highest peak and the needle just sits there until the meter reader resets it.
Then there are the meters that record usage and time of consumption to match to variable rates. These meters record demand and consumption.
In the case of the hairdresser if the local rates are flat the demand meter won't matter but the consumption might show he is using more electricity a month than he is paying for. I know if I was the landlord I would install meters on each tenant regardless of rate structure and I would want a demand meter on the service in case I had spare capacity in the service that could be exploited.

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#194579 - 06/11/10 01:06 PM Re: Demand Meter Help [Re: mikesh]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
Mikesh:
Quickly, what I wrote herein is in regard ti the check meters, or sub-meters that are used for revenue collection from tenants within a structure that has a single utility meter.

'Demand' is the available capacity that the POCO has to have available to provide power. Basically, what Tesla said above.

Also, keep in mind I am in NJ, USA, not my neighbor to the north...Canada. Our electric rates here are probably a lot more than Canada's.




The 'Demand' charges are quite substantial, and IF the bldg owner in the above scenario does NOT install demand sub meters, he will eat the demand charges!
_________________________
John

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#194582 - 06/11/10 03:25 PM Re: Demand Meter Help [Re: HotLine1]
mikesh Offline
Member

Registered: 06/07/06
Posts: 614
Loc: Victoria, BC, Canada
Hot line
Thanks for the explanation of terms. We call it a consumption meter or utility meter and only a demand meter if it records peaks rather than just recording total consumption. I see from Tesla's explanation that peak loads are a problem on some grids and I infer that most utility metering in your area include the ability to record peak demands and charge a premium for exceeding it.

Toronto is likely on the same grid as New York and Michigan and I know that area does have peak load times where brownouts occur.
Here in BC Demand meters are relatively rare except for the Electronic meters slowly replacing the mechanical types.
We mostly use them to monitor peak loading to identify excess capacity in a service or feeder.

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#194585 - 06/11/10 04:58 PM Re: Demand Meter Help [Re: mikesh]
twh Offline
Member

Registered: 03/11/04
Posts: 898
Loc: Regina, Sask.
We pay a charge based on peak demand.

My concern about insisting on a demand meter for the tanning salon is that the first 50 kva demand is free. The tenant would insist that their first 50 kva is non-peak and is therefore free. I think 50 kva is about 140 amps at 208 volt, 3 phase. They have a 200 amp feeder.

The landlord has been reading the other tenant's demand meter but when I look at his records, one number is always 160. Maybe it's the peak demand that hasn't been reset and he probably isn't charging for demand.

The demand meter is a Schlumbeger Vectron. It has a multiplier of 1 but since it's connected to ct's I don't know what that means.

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#194587 - 06/11/10 07:58 PM Re: Demand Meter Help [Re: twh]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
First, get a current copy of the owners POCO bill and see what the POCO demand figures are. The 1 tenants demand cannot exceed the POCO numbers.

What you would do if 50 is included within the 'base' utility fee is deduct 50 from whatever the guys demand reading is on his meter. For two tenants, deduct 25 KW from each. They will complain, but thats about the only way to do it. The ultimate solution is for each tenant to have a POCO meter.

If you are getting involved with the reading of the subs, I strongly suggest that you obtain at least six current POCO bills, obtain the POCO rates, and determine IF there are any laws regarding sub-metering and pricing.

Here in NJ the rates/fees charged to any tenant cannot be greater than the POCO rates. An 'Administrative Fee' is the onlt adder charge that a landlord can charge. There is no definition of the 'Adm. Fee', but reasonable charges for reading and billing processing were OK.

The multiplier is a factory number, based on the ratio of the ct's and the meter electronics. ie: 200 amp CT's with a meter rated at 200 amps, 1 multiplier; The CT's are usually 5 amp output on a 200 amp load; different CT's result in a different multiplier. A '1' is easy!
_________________________
John

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