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 Post subject: A few questions for configuring my purchase
PostPosted: Sun Feb 12, 2017 5:07 pm 
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I'm planning to buy a GEM and DashBox for monitoring power in my house, and I've been reading documentation and forum topics to get up to speed, but I have a few questions.

I have two main breaker boxes. Each has a 200A main breaker. I believe I need a total of 4 Split-200 CTs to cover the incoming power (Panel 1 Phase A, Panel 1 Phase B, Panel 2 Phase A, Panel 2 Phase B, which I'll abbreviate as P1PA, P1PB, P2PA, P2PB). I can connect 2 CTs to each channel on the GEM. Questions:

1. Does it matter how I combine these CTs? For instance, I could group by panel: Ch 1=P1PA+P1PB, Ch 2=P2PA+P2PB, or I could group by phase: Ch1=P1PA+P2PA, Ch2=P1PB+P2PB.

2. Either way, the total power I'm using will be Ch1+Ch2. I assume there's a way in the DashBox's configuration to tell it that the mains are the sum of Ch1+Ch2?

3. Assume, for simplicity, that I am monitoring the mains as above, and a few loads (e.g., Washer, Dryer, Heat Pump on channels 3-5), and that remaining unmonitored circuits are lights/outlets, which I'll call "Other". Does the software in the DashBox compute "Other" (in my example, Other=Ch1+Ch2-Ch3-Ch4-Ch5) so that I can see on the graphs and reports how much power is going to these lighting/outlet circuits without monitoring them individually?

4. I have a subpanel that is fed by a 125A double throw breaker. The closest CT I've seen on Brultech's web site, that's sized larger than that, is the Split-170. But I saw in another thread (viewtopic.php?f=3&t=486) that it's listed as "Special Application, Bus Bar". Can I use two Split-170's to monitor the power going to this subpanel, or is it special in some way and I need to use two Split-200's?


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 Post subject: Re: A few questions for configuring my purchase
PostPosted: Mon Feb 13, 2017 12:43 am 
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If you have two 200 amp panels it comes down to (IF) they are fed off one meter or two. If there is only one meter and both are fed off of that single meter it really comes down to preference whether you monitor each leg of the split single phase electrical system or the individual breakers.

The benefit of monitoring both main 120 VAC lines is higher accuracy, negating individual CT variance, and being able to see the *Big Picture* of each main panel.

Keep in mind its up to you if you want to combine each panel in to a single channel or use two channels.

You will need to read the full users manual which states the maximum each channel can sustain.

Meaning panel 1 has 1A & 1B which goes to channel one of the GEM. Panel 2 has 2A & 2B goes to channel two of the GEM. I'm not sure why you would ever try to combine panel 1 with panel 2's opposing lines?!? :?:

Also, some users like myself monitor each 120 VAC legs on separate channels. I did this because I wanted to know load balance in the home. It also made it easier to monitor solar NET energy production / consumption.

The DB has a *Group* method to add / subtract loads . . .

Lastly, if a circuit isn't being monitored individually it would be up to the end user to determine the energy signature from viewing the *Global* energy consumption via the two / four Split-200 CT's. The DB also has a (basic) energy detection algorithm but obtains that information based on dedicated CT's monitoring said circuits to render that data.

There is no guess work here like many of the toy like energy monitors such as Sense, Smappy, etc.

Regarding the Split 170 CT Brultech will need to comment on that as I have no personal experience with that CT. From a practical stand point all that matters is (IF) the CT will go around the wire conductor properly and configured in the GEM to use the required specifications.

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 Post subject: Re: A few questions for configuring my purchase
PostPosted: Mon Feb 13, 2017 1:24 pm 
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Thanks for your quick reply! I forgot to mention that these two panels are touching each other, covered by a single meter. It's as if it's a single 400A panel, but it's just broken into two.

I had assumed I'd monitor per-panel---I can't see any reason to combine the phases either. I just wanted to ask in case I might be missing something! I suppose that there is an advantage in per-panel monitoring, in that you could compute "Other Panel A" separate from "Other Panel B".

To tell the truth, I believe I can cover all my circuits plus the incoming mains with the 32 channels that the GEM provides. I was just asking about computing the difference ("Other") as a precaution in case I can't. My main interest was whether I can add the two main channels in order to know my total consumption. It sounds as if the Group feature will cover that need perfectly.

Hopefully, Brultech will comment on the Split-170 question. I'd prefer to use that over Split-200s if it works, since it should be a little more accurate, being closer to the actual maximum current, and also a bit smaller which would help with space issues in the panel.


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 Post subject: Re: A few questions for configuring my purchase
PostPosted: Mon Feb 13, 2017 1:55 pm 
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If the arrangement is Meter ->Panel 1->Panel 2 you need only purchase two Split 200 CT's to monitor the primary feed for the entire home. Not only would this reduce costs but save on one GEM channel. Then, again it really comes down to use case and preference as there isn't a right or wrong. :P

As noted the benefit of having both panels monitored at each main feed is being able to see on a global scale what each panel is drawing down for that big picture. A few GEM owners have done just that along with monitoring each of the individual circuits for more detail.

Keep in mind if your electrical system is wired like I illustrated above you need to be aware to NOT indicate the one panel is a *MAIN*. Doing so will impact the proper electrical math in the DB system.

Meaning technically the second panel is considered a super large *Sub Panel* being fed off of the primary main panel.

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 Post subject: Re: A few questions for configuring my purchase
PostPosted: Mon Feb 13, 2017 3:06 pm 
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Thanks again! Neither panel is a subpanel of the other. The power comes inside from the meter, goes through a sort of splitter box, and then goes into the two panels through the two 200A breakers, like this:

Code:
          +-- (200A breaker) Panel 1
          |
Meter--+
          |
          +-- (200A breaker) Panel 2
                                       |
                                       | 125A breaker
                                       |
                                       +---Goes to remote subpanel in the garage


And of course, each of Panel 1 and 2 have a bunch of other 120V and 240V breakers not shown here.


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 Post subject: Re: A few questions for configuring my purchase
PostPosted: Mon Feb 13, 2017 3:31 pm 
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In that case *YES* you would need two pairs of Split 200 CT's to monitor the two panels. I have to gather you live in a huge *McMansion* 400 amps just wow! :o

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 Post subject: Re: A few questions for configuring my purchase
PostPosted: Mon Feb 13, 2017 4:31 pm 
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LOL I know it's a lot! And my bill reflects that, hence my interest in energy monitoring :-). It is pretty much all electric, and it was built in a time when (a) builders didn't build for energy efficiency, and (b) electricity was very cheap (Pacific Northwest), so no one cared. We've done what we can to tighten up the house (using blower door and thermal imaging testing), add insulation, etc., which has really helped, but we still use a LOT of electricity per day, so I want to get a handle on where it's going.

No more old houses for us---our next house will be extremely energy efficient! A local builder makes extremely efficient houses that cost only $200-300 per YEAR for heating and cooling.


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