What would be the best way to monitor electric usage over 50 circuits?

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  • ludditeal
    Automated Home Sr Member
    • Feb 2004
    • 62

    #46
    Maybe old news or already discussed but someone is flogging single din 50 Amp meters with pulsed output for £12.95 + £3pp on E-bay.
    See item 200372094031

    Regards
    Allan

    Comment

    • Gumby
      Moderator
      • May 2004
      • 437

      #47
      There is also a module from JWInstruments at this kind of price.

      However, there seems to be quite a few Chinese clones floating about and it's difficult to know about quality. There have been some horror stories of counterfeit MCBs with no actual breaker mechanism inside them!
      ----------------------
      www.gumbrell.com

      Comment

      • RichardC
        Automated Home Jr Member
        • Mar 2009
        • 29

        #48
        Recently purchased two 1 unit kWh meters from OCS GmbH

        Their English website is:



        These will be connected to my soon to be installed Idratek system.

        16.99 Euro each.

        Search for ART-474-200828 to find them.

        They look ok, I hope that they are not too dodgy, I will be installing them over the next week and will see how they behave.

        The postage cost was almost the cost of one of the meters. Plus they do charge for Paypal.

        If anyone is interested in combining orders, if this is of interest, then please let me know. They are willing to give discount on orders of 10 or more and I will need just more than 10 to complete the installation in my CU. Plus if I have more time I can transfer the money to a friend in Germany who can transfer the money and not incur the Paypal charge.

        Comment

        • Gumby
          Moderator
          • May 2004
          • 437

          #49
          You might want to put a post in the bulk buy forum as well. The last time I don't think there was any extra interest, but you never know.
          ----------------------
          www.gumbrell.com

          Comment

          • chris_j_hunter
            Automated Home Legend
            • Dec 2007
            • 1713

            #50
            might be of interest ... latest issue of Which? magazine reviews seven energy meters & reckons accuracy varies (up or down) quite a lot with load & between devices, best within 0.5% & worst within 12.5% ... can handle one to four tariffs, according to device, and only four of them can be connected to a PC ... prices within the range 25 to 50GBP ... Current Cost, a couple of Owls, a couple of Eco-Eyes, & a couple of Efergys ...
            Last edited by chris_j_hunter; 26 September 2009, 09:40 AM.
            Our self-build - going further with HA...

            Comment

            • Paul_B
              Automated Home Legend
              • Jul 2006
              • 608

              #51
              From memory and experience the devices you listed at the end all work on current clamps. So as current clamps only work with resistive loads they are going to be inaccurate by design. The devices mainly discussed in this thread are DIN mounted and measure both current and voltage to output power.

              Paul

              Comment

              • chris_j_hunter
                Automated Home Legend
                • Dec 2007
                • 1713

                #52
                yep, that's right ... looks like I got my threads mixed-up - thought it was this one that had mentioned the current clamp meters ... looking back, though, now, it seems there was just a passing reference to the Current Cost ... ie: maybe it was the earlier thread that took them more seriously !
                Our self-build - going further with HA...

                Comment

                • RichardC
                  Automated Home Jr Member
                  • Mar 2009
                  • 29

                  #53
                  Originally posted by Gumby View Post
                  There is also a module from JWInstruments at this kind of price.

                  However, there seems to be quite a few Chinese clones floating about and it's difficult to know about quality. There have been some horror stories of counterfeit MCBs with no actual breaker mechanism inside them!
                  I'm just setting up a trial between one meter I brought from the German company I wrote about on this forum (which will do a max current of 32A) and one from Stephen P Wales (which will do a max current 45A) all in series along with a CALMU calibrated kwh meter. All three also going into a QRI-002 to compare the pulses. As the din rail mounted units only output 20ms length pulse which is right on the limit that Karam says will work. Fingers crossed!

                  I needed one at 45A for one of the showers. Comparing the two units, they look to be from the same source with moulding marks in exactly the same area, with only the ID on the side being different.

                  Will follow up in a couple of days.

                  Comment

                  • RichardC
                    Automated Home Jr Member
                    • Mar 2009
                    • 29

                    #54
                    Originally posted by RichardC View Post
                    I'm just setting up a trial between one meter I brought from the German company I wrote about on this forum (which will do a max current of 32A) and one from Stephen P Wales (which will do a max current 45A) all in series along with a CALMU calibrated kwh meter. All three also going into a QRI-002 to compare the pulses. As the din rail mounted units only output 20ms length pulse which is right on the limit that Karam says will work. Fingers crossed!

                    I needed one at 45A for one of the showers. Comparing the two units, they look to be from the same source with moulding marks in exactly the same area, with only the ID on the side being different.

                    Will follow up in a couple of days.
                    (bit more than a couple of days!)

                    The results were as follows. Over a two day period, all lighting circuits were fed via the three meters. I have also got 15 days worth, but thought I would hit the two days first to see if it's worth going for the 15 days.

                    59 pulses from the Calmu meter = 0.59 kWh, the meter read 0.59 kWh. The meter setup was verified with a tungsten lamp at 40w and it did read 40w.

                    698 pulses from the 45amp meter = 0.698 kWh, the meter read 0.70 kWh. There was no setup to verify.

                    705 pulses from the 32amp meter = 0.705 kWh, the meter read 0.70 kWh. There was no setup to verify.

                    7 pulses diffrent. So only a 0.01% issue there. But the two din meters did read quite a bit higher.

                    I am going to put the Calmu meter on my incomer and will verify that against the rec. meter. But I will be changing CT's from a 20/5 to a 80/5 for this. I will be using the 20/5 with another Calmu meter and will compare against one of the din modules to work out the diffrence.

                    I am more interested in that the Calmu meter seemed to be spot on, both in pulses and the reading. The DIN meters are to be used in a more indicative role, so that I know roughly where the power is being used.

                    I have split off all the computers onto one big UPS now, and will feed them separately. So will have a house base-load and also a computers base-load. I think I am going to find this info scary.

                    Am ordering another 11 of the 32A meters later on today. Will be interesting later on to add them all up and check to see if they are still appear to be reading high. Will also now do a check against one of the ring main so will have some proper amounts of kWh to play with

                    Next task - water and gas meters.

                    Cheers

                    Richard

                    Comment

                    • Kevin
                      Moderator
                      • Jan 2004
                      • 558

                      #55
                      Originally posted by RichardC View Post
                      Will be interesting later on to add them all up and check to see if they are still appear to be reading high. Will also now do a check against one of the ring main so will have some proper amounts of kWh to play with

                      Next task - water and gas meters.

                      Cheers

                      Richard
                      Interesting Richard - Aside from the actual accuracy of the measuring I would always have expected the pulse counts to read low if anything (if there were any pulse missed) . So it seems either the DIN units do measure high - or the Calmu low - although you have verified it against the load. I gather it's connected via CT's - and I assume has a voltage connection too ? I wonder if they vary and light loads introduce more error.

                      I have my gas and water metered and the pulse widths are no problem there. My water meter is quite sensitive but the gas less so. I tried to order a more pulses/m3 gas meter but the company said they were all the same, based on a standard. These meters, particularly the gas one, do click a bit as they count so worth ensuring they are out of earshot.

                      These sort of exercises do pay off as you become obsessed with consumption. My computers that were 24/7 are a major electrical culprit as the graphs clearly show. I've got a few ZigBee plugs that switch/monitor KWHr too on particular appliances.

                      At the moment I'm focussing on heat loss from my hot water tank. I have a circulating hot water system, along with a towel rail off a secondary coil in the cylinder and it's surprising how much extra heat loss this causes. I'm looking at timing or intelligently switching these two. With the circulating hot water however this causes a churn of cold water back into the cylinder.

                      K
                      Last edited by Kevin; 26 October 2009, 01:25 PM.

                      Comment

                      • chris_j_hunter
                        Automated Home Legend
                        • Dec 2007
                        • 1713

                        #56
                        v.interesting - thanks for posting ... not sure the test with a 40W bulb would be anything but a rough guide (unless I misunderstood), their rating must be nominal & of course dependent on voltage ... the house meter might be the most accurate, if some way of running them (or just the CALMU, if that's in-doubt) against it for at least a few hours, preferably days, could be devised ... mind you, 'would've thought the CALMU would be OK !
                        Last edited by chris_j_hunter; 26 October 2009, 06:47 PM.
                        Our self-build - going further with HA...

                        Comment

                        • chris_j_hunter
                          Automated Home Legend
                          • Dec 2007
                          • 1713

                          #57
                          looks like Current Cost have some new units out :



                          useful or ... ?

                          Chris
                          Our self-build - going further with HA...

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