OpenEnergyMonitor Community

CT Sensors

I just moved to a new place, and when attempting to install the eMonPi into my panel, I discovered that the CT doesn’t fit around the 4/0 feed lines coming in from the meter. At my previous place, it was a 150A panel. Is this just a matter of getting a different set of CT? It’s also a 150A panel, and the feed lines are aluminum (hence the 4/0 wire for such a small panel).

Alternatively, is anyone aware of a way to read the smart meter via Zigbee?

You will need two new c.t’s - there’s a page in Learn with a list of c.t’s that are known to work with the emonPi. Learn→Electricity Monitoring→AC Power Theory→Use in North America→Use in North America

The only known way at present of getting data from a smart meter is to count pulses, which has its own problems if you want more than the total cumulative energy.

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I think the long range solution will likely be to get a smart load center like the one Leviton offers, and do that as part of getting rid of alumin(i)um wires - but that’s a much more long range solution at the moment.

I’m curious… Why do you want to get rid of the Aluminum wiring?

We’re going for ali cables here. A friend who used to live in rural Scotland woke up one morning to no electricity. In the night, metal thieves had come along and stolen the copper overhead lines to his property. The network company replaced them with ali.

With the price of lumber these days I’m surprised the thieves aren’t stealing the wooden poles.

But they haven’t quite gotten the memo that copper was only very temporarily valuable enough to steal… 15 years ago.

They also steal fibre optic comms cables laid alongside railway lines - in the hope there’s copper inside.

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Safety, mostly. It’s 45 years old. It’s only on the high current circuits for the range (I have a gas range, so it can just come out entirely) as well as the main feeder (which has decent anti corrosion on it at the moment, but I don’t know the condition of the other end that’s outside.

Our overhead lines outside are generally aluminum because of weight.

Can’t blame you there. Mechanical connections in aluminum wire are a well known fire hazard.

That varies considerably.

From what a friend tells me - he was the electrical superintendent for the town he lives in - ACSR
(Aluminum Core Steel Reinforced) is likely the most common material used in overhead power lines.
Copper and Aluminum i.e. not ACSR, are used too, but to a much smaller degree.

Update: Ordered a set of the 200A CTs, and, well, There’s no good way to get them on. they come apart into 2 pieces to get them around the line, but there’s no way to actually get the damn things back together. They look like they should just snap together, but that doesn’t seem to be the case (yes, I checked the alignment of the teeth - they simply don’t want to go back together). I definitely don’t want to be poking around with any kind of tools on the the hot side of a 150A main breaker.


Which make/version of 200 A c.t. do you have?

I was finally able to get it to go, it required fiddling with the conductor gaps with a screwdriver to make them fit together again and very carefully using a large set of channel lock pliers uncomfortably close to the main lugs.

Still need to wipe the config, since I’m getting negative values on one leg, and need to make sure they’re properly calibrated.

Now that it’s done, where is the config file mentioned in the screen shot: 200A max clip-on current sensor CT - Shop | OpenEnergyMonitor? My system shows it in 2 locations:


Which one is the active one?

The easy way is go in via a web browser → Emonhub → Edit config

And the scale for the 200A CT is still 3,3,3?

That depends on the secondary current. As I don’t know your c.t ratio, because you haven’t answered my question, I can’t say.

What question?

The one where I asked which c.t. you have. Or you can tell me its ratio. I can get the second from the first, but the second avoids a look-up and would be simpler.