Page 1 of 3

Connecting ct's to GEM

Posted: Sat Apr 22, 2017 6:20 pm
by Sbe
Couple of questions how do you connect the main line to the GEM. I know you use two split 200's but do they go into one channel or two channels. Same question for 240 v loads. Again two CT's used but do they go to one or two channels. Likely a stupid question but it is not in instructions.

Re: Connecting ct's to GEM

Posted: Sat Apr 22, 2017 7:00 pm
by Teken
Hello SBE,

There are two types of CT's Split and Solid. The Split CT are 60, 100, 200, 400. The Solid CT are Micro 40, 50, 80, 100, 170's.

The Split CT's are Type A and the solid are Type B.

The GEM Installation Manual describes all the details and installation starting on page 18. The Split 200 can be inserted into the PJ of 1 / 2 & 3 / 4.

Ensure you read and observe the correct orientation and polarity of the wiring into the GEM. The choice to use one or two channels for each Split 200 CT comes down to preference and need. 90% of the people and install combine both Split 200 main CT's into one channel.

The benefit of doing this is you can see both sides of the electrical feed as a combined wattage total. For me and the 10% of the users we installed each Split 200 CT on their own channel which allows me to see what each side of the main feed is drawing in terms of power.

I did this so I could at a granular level say *Hey this side is less / heavily loaded* so when I embarked in any electrical work I would know and could see a over load condition etc. This also allows me to have hyper local NET metering capability as I can see my solar power streaming in and can make adjustments etc.

RE: 240 loads: If the load is a *balanced* 240 VAC load you have the choice of using one single CT and enabling the 240 software doubling feature. Or use two CT's for more real time accuracy either method is fine and comes down to preference, costs, and need.

Like the Split 200 main CT's if you decide to install two CT's into a single channel be cognoscente of polarity of the wiring inserted into the GEM. If you make a mistake in the *Physical Direction* of the CT's at each breaker you need only reverse the orientation of the wires at the GEM PJ.

You will know if its wrong because if you unplug just one wire pair the wattage will go up. If you insert the second pair and (lets assume its incorrect) that 100 watt load will split in half to 50 watts. So, you need only reverse the direction of the wires and the load should go back up to to 100 watts.

NOTE: The GEM PCB has the two different CT's with a wiring schematic of how each is wired.

Re: Connecting ct's to GEM

Posted: Sat Apr 22, 2017 8:44 pm
by Sbe
Taken

Thank you very much I just wasn't sure if I have to use one channel or two channels. I will use two as I bought two GEM so I can monitor 64 channels if I need to.

So I when you send up the monitoring you just tell it what each is so two channels for stove will be labeled stove and same thing for main one left and one right main.

Again thank you very much.

Shayne

Re: Connecting ct's to GEM

Posted: Sat Apr 22, 2017 8:59 pm
by Teken
For the stove you would need two CT's and combine both into one single channel. The reason for doing so is sometimes the convenience outlet is used on the stove top.

This way you can ensure anytime it's used that power consumption is recorded for the stove and doesn't use up a GEM channel. It should be noted *Ideally* an electric hot water tank should draw the same power but many newer tanks cycle the top vs the bottom independently of one another to meet energy star ratings etc.

I call this out because if you decide to use one CT and enable 240 VAC doubling the power & energy consumption may not be 100% accurate.

This is why it's important to measure both feeds on a balanced 240 VAC load first. If you find both sides draw the same then you can save time and expense by using just one CT on that balanced load.

Good luck on the install and ask questions when needed.


=========================

The highest calling in life is to serve ones country faithfully - Teach others what can be. Do what is right and not what is popular.

Re: Connecting ct's to GEM

Posted: Tue Apr 25, 2017 1:03 pm
by Sbe
So I think I am close . All cts hooked up. Mains are on separate channels (actually separate gems channel one on each). All my 240s have 2 cts and on same channel (1_2 and 3_4 not high on 1_2) .my split 200s the arrows are pointing to barker box all other cts pointing away. Not sure if it matters but for a type I used 3_4 and put white o top and for b type use 2_3 put white on top. Attached both GEMS to dash box directly and dash box to Ethernet. Was able to configure everything on GEMs and said what cts each channel had .

Does this sound OK? The one weird thing is one channel has more usage than the main and this is true for both mains (one of the channels is very large) is there something I have done wrong ~ note I just set up the GEMs with right cts this morning so for 10 hours they were all micro 40s.

Also one more question for circuit with ground fault breaker I just put one split 30 on load and nothing o neutral is that correct?

Sorry for all questions

SHAYNE

Re: Connecting ct's to GEM

Posted: Tue Apr 25, 2017 1:08 pm
by Teken
Hello Shayne,

If you really did in fact place each *Main* Split 200 CT on separate GEM's. I would humbly suggest you change that configuration because it will cause nothing but headaches in terms of reported values and will be near impossible to trouble shoot.

For a 120 VAC GFCI circuit you need only place the CT on the load side.

Re: Connecting ct's to GEM

Posted: Tue Apr 25, 2017 1:55 pm
by Sbe
I will change that as I can not figure out the numbers they are of adding up. Can I put mains on two channels still.Thank you

Re: Connecting ct's to GEM

Posted: Tue Apr 25, 2017 1:56 pm
by Teken
Yes, they can be placed on channel 1 & 2


=========================

The highest calling in life is to serve ones country faithfully - Teach others what can be. Do what is right and not what is popular.

Re: Connecting ct's to GEM

Posted: Tue Apr 25, 2017 2:49 pm
by Sbe
Ok left main channel 1, right main channel 2. Total W is 1700 Left main shows 1700and right show 850. I know the left should be at 850. This is on the Overview Live page with the speedometer gage but when I say show all channels left is 850 and right is 850. Not sure if it matters. I will look at it for a few days and hopefully it will start to make sense as right now it says all consumption is from right side and virtually none from left but the mains themselves say 55% right and 45 left. Now that I have mains iPod one GEM that may fix that.

Re: Connecting ct's to GEM

Posted: Tue Apr 25, 2017 2:56 pm
by Teken
Hello Shayne,

Just some quick follow up and confirmation in no specific order of importance or relevance:

GEM: Ensure both channels 1 & 2 have been assigned the correct CT parameters for a Split 200. When you look down the column for both you will see the exact same Type & Range they should both match one another.

DB: Ensure both channels 1 & 2 are marked as *Mains* in the Energy Monitors.

Solar: Do you have solar NET metering?