Compatible CTs for IoTaWatt

Hey there,

Does anyone know where can we get split core 200A/250A/400A CTs compatible with IoTaWatt … in the EU ? Wondering because buying AccuCT from the US… the shipping is >250$ and they don’t have any EU stock…

Getting something from Aliexpress/Alibaba - there are a lot of cheap options, however … 30+days shipping and no guarantee if what we get would actually be useful (and accurate).

If someone knows a good sourcing in the EU that won’t break the bank, or has experience with the chinese CTs (usefulness, configuration in IoTaWatt, etc) - please share here.

Looking forward to hearing from you guys.


Not trying to discourage you from seeking alternate sources, but want to correct the record on shipping from the US to EU. Economy shipping is $20 < 2 lbs, $25 < 3 lbs, $35 < 4 lbs. Takes a few weeks these days.

UPS to Europe is between $50 and $70 for most destinations with about a week delivery.

The only item not stocked for Europe is the voltage transformer. They are made in China and carry a 25% extra tariff for import to the US. Add the shipping from China to US and then to Europe along with the 25% tariff surcharge and it makes no sense. The website has links to EU sources for those.

The Echun CTs are high quality and available from China. Be sure to get 0-50mA output and 3.5mm jacks.

For 6x AcuCT-H138-400:333 + 6x AcuCT-H100-250:333 I was quoted 516$ cost + 264.91 shipping “UPS EXPEDITED” (Even though I didn’t specify expedited and they didn’t provide any other options upon the quote)

If, as you say AccuCT are made in china - do you have any way of ordering them from china directly to the EU (even unbranded, the quality should be identical)?

I’ll need to monitor 3 locations, each having 2x 3-phase feeds (the 400A clamps would go there) + various loads on the 250A internally (including solar). That makes a lot of CTs and at least 2x IoTaWatt devices per location.

Can the CT wires be extended, say, using 3.5mm f + 3.5mm m, and by how much?

A lot of misinformation above.

The quote above is not from the IoTaWatt stuff store, and those CTs are not compatible with IoTaWatt. Also, the store doesn’t carry 250A CTs, and I did not state that AccuCTs are from China. they are from Canada. I said Echun is from China.

6x400A and 6x200A from the stuff store is $456 USD. Don’t know the destination in Europe, but for example shipping via UPS Expidited (lowest cost) to Belgium would be $108.52.

The CT cost goes down to $405.60 when the 200A are ordered with base units in a Generic Kit. Shipping should be about the same. Add $398 for the base units.

You are welcome to shop elsewhere for CTs. That’s part of the open commitment. But please stop posting vague inaccurate information.

I needed 400A and 250A CTs (preferably AccuCTs). Since I saw you don’t have 250A CTs, I contacted AccuCT directly and the quote is from them.

Why don’t you have 250A CTs available?

There is no demand. Also, in the USA circuits are supposed to be protected with a breaker rated to 125% of expected load. That would be 200A expected load on a 250A breaker. Don’t have any details for your authority’s requirements.

That’s probably for household… My use case is 3 hotels in Golden Sands, 2x3-phase feeds each.
Not sure the value of the main circuit breakers but I think they are 400A or 600A.
They each also have 55 kW solars.

I’ll check with management if we can make a single order through you (that is - if you can source 250A CTs) and get everything in one go.

If you need greater than 200A, I stock 400A at $48. I won’t be special ordering 250A.

What CTs are compatible with these:

Probably would need to put the CTs on the cables above rather than the bussbars.

Not possible … The hotel has 4 3-phase lines, each with 2 cables, i.e. a total of 24 fat cables.
The plan is to have 2x IoTaWatt, each having 2x3 phases directly on the bus bars - to split the hotel in two for the main feeds + 3 cts for a separate inner circuit.
If I have to place CTs on the cables, I’d have to purchase 4-5 IoTaWatts … that’s not gonna work for management.

Suggestions… ?
Would normal split-core CTs work on a busbar ? If so - are there gonna be any issues…

They will work on a busbar, but I don’t see how you could get one around those busbars.

How many Amps in each pair of cables? The 400A and 600A CTs are 36mm and would probably go around both cables.

Or combine each pair of CTs into one input. If each cable is no more than 200A, it would cost less than 400A CTs. The standard approach for combining requires oversizing the CTs. If the two cables are 200A each, the standard approach combines two 400A CTs. But there is another way. You can combine two 200A CTs if you change out the burden resistor to 10 Ohm, or add a 20 Ohm resistor in parallel with the input to in effect make it 10 Ohm.

I’ll ask about the cables @ Monday. As for the bus bars - they are 3.5~4 cm wide, 0.5cm thick. There’s more space at the bottom of the breakers.

Unfortunately a single CTs won’t be able to go around both cables because they aren’t close (and are quite thick).