Internal electric metering options
Is there a way to meter electric usage by different applicances/mechanical units inside the house ?
Let’s say there are two hotwater heaters with one of them serving a small accessory apartment, is there a practical way to meter the power consumption to the second water heater for the purpose of splitting up a elec bill ?
Thanks !
Alan
Replies
Some electric companies have a program for electric service that is timed. That is, they are allowed to turn it off (via a radio transmitter) during peak service periods. In SE Michigan, Detroit Electric has these on lots of people's electric water heaters (the water will stay warm for a while so its not real noticeable to live with the interupted service).
The bonus is that electricity is cheaper.
They send you two bills each month.
If you don't have this available, or don't want it, you will have to arrange for a second meter at your own expense, and it would have to serve a separate panel inside the house, and the two systems would have to be kept quite separate (maybe very expensive for you to do this).
Norm
I would say that it depends on what type of splitting up of the electric bill you are talking about. If it's for legal submetering for a tenant, then I agree with Norm, you have to buy a regular electric meter and install it on the submetered load. The cost for that would be up to you.
There are some other options that might be cheaper and more versatile, if you are in a less formal situation than the legal restrictions that a lease places on charging a tenant for utilities. You might look at http://www.onsetcomp.com and check out their HOBO meters. They have an on-off logger that would tell you the exact runtime of the water heater, then it would be a case of multiplying the run-hours by the rated kW of the heating elements. Another option would be their external channel loggers. You could monitor temperature and current over time, at some short interval. Since the water heater is a purely resistive load, you could easily convert current into kW, and then into kWh.
I guess it really depends on what you plan to do with the data. The reason I bring up the HOBO loggers is because they are inexpensive and offer a lot of flexibility. I use them at work to monitor all sorts of things. But they would not stand up to a legal challenge by a tenant that feels they are being overcharged.
Thank-you for your replies.
Hmm...I don't want to complicate this too much and I may be over-thinking this.
The "sub meter" would be in plain view of the tenant and the usage for the waterheater would be calculated off the main electric bill.
So...all I would want to do is to meter the draw to a water heater.
Currently a 80 gallon elec water heater serves the whole house and runs off the main house panel.
Installing a separate water heater off the apartment panel would be simplest solution if I am comfortable w/ adding that circuit to the Apt's 100-amp panel.
(I have another post concerning 100 amp service.)
Thanks for your feedbacks.