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My GEM installation - part 3, GEM wiring

published, Aug 28, 2012 8:25pm
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Now that the CTs have been installed in the two panels, a short description of how I wired up the GEM.

As part of my home rewiring projects, I'm also running coax and CAT5 to every room, and have a 1-wire bus that runs through the house. All of this is mounted on a simple plywood panel. Clockwise from top-left: patch panel for cat5 to all rooms, different wiring bundles, incoming phone service and splitter box, in the middle right a connection box for the 1-wire network (plugged into it is the incoming connection from the GEM as well as a temperature sensor crimped inside an RJ45), the GEM intself, and my FIOS home router.

Brultech main panel wiring


The incoming CAT5 connections, with the main panel already plugged in. I simply used a CAT5 pair per CT, and in the case of two-phase circuits, these are combined here by plugging two CAT5 into the same sensor input. When you do this you have to pay attention to the orientation so that they add up; I found it easiest to simply try which one gave me the highest reading. You can also see the 1-wire cable in the block on the right, and the ethernet board on the right.

Brultech main panel wiring inside


Everything wired up with the cover on. Nice clean look.

Brultech finished


All pretty straightforward. In the next post I'll show the setup of the Brultech.


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Hi evandepol, excellent series of articles covering your Brultech GreenEye Monitor (GEM) installation - thanks for sharing! I have a home I'd like to add this product to as well. Here's my scenario followed by some questions I'm hoping you can help answer. I have 2 main panel breakers (200 amps each) flush mounted within stud bays sitting side by side. I also have a 100 amp sub-panel which is about 70+ feet away from the main panel (following the wire path). Ideally I'd like to monitor circuits from each of the 3 panels (though maybe not every circuit?). I would like to place a GEM in my garage near my 2 main breaker panels. At most, it might be about 15 or 20 feet of CAT5 wiring (give or take) to the GEM location from my main panels -- sounds simliar to your situation. However the length from the sub-panel would be 70 or 80+ feet given the path the wires may need to follow. Here are some questions I have around installation, setup and usage.

1) Using the CTs shown in your photos, it looks like these have black/white jacketed leads. Are those black/white wires part of the CT which you then splice onto the CAT5 within the external 2-gang box (e.g. to the left of your panel)? If so, what is the length of the CT wire leads?

My 2 main breaker panels are tall (at least 30") while the sub-panel is about 18". I'm wondering if there would be enough length to splice below the panel or if I could simply splice the CAT5 and CT leads within the panel itself? Outside the box within a separate 2-gang box is probably best, but I'm trying to understand how far away a junction box can be from the panel and still be within reach of those CT wire leads (to splice into a CAT5 wire).

2) How many wires does each CT include (e.g. how many wires does it take to monitor each circuit)?

If it's one pair per CT, then it seems I should be able to add up all the circuit positions, multiply by 2 and then add at least 1 extra CAT5 cable for redundancy. Does this sound correct?

3) Is there a CAT5 cable length limitation from the GEM to the panel(s) being monitored (e.g. maximum cable length)?

4) What technology are you using to monitor your GEM device? Is it a wired [ethernet] connection, wireless or are there other options? I have both a wireless router and a Z-Wave network and wondered if connectivity to my Z-Wave network is possible?

Lastly I'm wondering what a "one-wire" bus provides? Is it literally a single wire running from room to room (daisy chained) or does it home-run back to one location? What can you do with that bus wire down the road?

Thanks for the great series of articles!
Dave (NetworkGuy)

One more question I meant to include: in the center-right side of your equipment, you have your connection box for the 1-wire network. You said it is plugged into a line coming from the GEM, and it includes a temperature sensor crimped inside an RJ45? What does that monitor and/or provide to/from the GEM? And what is the temperature sensor about and what are you sensing in that line? If it's temperatures in each room, what kind of sensor are you installing and where do you put it within the room? Is it visible or somehow hidden?

If it is temperature sensors in the room, I'm wondering if that's something which could come in handy down the road with my own home! How do you anticipate using them?

Thanks for all the information and advice!

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