Can i extend the cables on the Split clamps?


my 3phase AirCon is about 4 metres away from where i am planning on locating my IOTAWatt (which is next to my main distribution board.

Can i extend the cables on the CT clamps for this to work ?

My plan would be to leave the standard probe in tact and get a 3.5mm socket and plug and make an extension cable from this

is this OK ??


You can simply use commodity headphone extensions, being careful to route them away from AC cables. You can find inexpensive extensions on eBay or AliExpress.

Excellent thanks


Is there a limit on how long of a extension cable I can use? GSHP system is being put in and they are using a 100A subpanel about 25 feet away (which will have 3 heat pumps and a hot water hybrid electric heater)… I’d really like to be able to monitor each unit individually (and my understanding is the symphony waterfurnace system doesn’t do real time electricity monitoring). I think ideally I’d run the extensions in conduit together.

25’ is generally OK. I have used simple headphone extensions with good results. Quick look turned up this source which looks fine at a reasonable price. They also seem to have them in about 5’ increments, so once the branch panel is in, I’d run a string to be sure of the needed length.

Running in conduit is good, especially grounded metallic. Don’t undersize, the cost of larger EMT is minimal.

Is it going to be an issue running 4 extensions in the same conduit as far as interference? I should be able to avoid any passing AC wires.

I haven’t actually done it, but I don’t believe you will have a problem. Many installations have several feet of 10 or more CT cables running in conduit with no reports of problems.

The previous wisdom on this subject was heavy on theory and light on empirical results. To flesh it out I got a load of headphone extensions tried them out. Putting two identical CTs on the same primary conductor, I looked for any observable difference with various length extensions on just one of them. I could find no difference. I did not test for any interaction between two or more extensions, but you will be in a position to further this body of knowledge by posting your results, which I have high confidence will be successful.

Induced noise from high-current conductors in close proximity are still a potential noise issue. That’s why I mention grounded EMT rather than the plastic conduit that I see many using appropriately for short runs away from obvious high-voltage wires.

Thought I’d share my experience (frustration) with cable extensions, particularly since I don’t see any reviews of the monoprice cables on the forums. I ordered 4 6’ inexpensive extenders from ebay, twice. Of the first 4, 2 worked, 1 worked to transfer music from my phone but not with the CTs, and one didn’t work at all. Of the second 4, all worked to transfer music but not with the CTs. So I ordered 4 of the monoprice 6’ cables linked above. Unfortunately I didn’t look closely at the pics on their site first. These cables are THICK; each “cable” is actually 2 cables between the male and female ends. They might work but there’s no way they would fit in the conduit I’m using. I’ve now ordered 6 different kinds of extenders from Amazon. I only need 4 but I suspect some won’t work. I’ll report back on which worked and which didn’t.

When you say they don’t work, what exactly do you mean? Are you getting zero watts or is it that the values are not what you expect?

Can you verify that these are stereo or mono extensions and not four conductor?

Have you verified that the plugs are fully seated on both ends?

I ask these questions because I have tested quite a few of these and never had even one fail to produce results.

UPDATE: Searched back and this source has quality extensions for very reasonable prices. I have tested:

G5212846 - 6"
G7448384 - 6’
G7561845 - 12’
G7577902 - 25’

These are well made utilitarian cords. I find that Amazon and others are typically catering to the audiophile community with gold plating and color/texture schemes that have little to do with functionality but exploit the whims of those with disposable income.

Hi Overeasy. Here’s a link to the Ebay cables I bought: Standard 3.5mm Stereo Not sure how durable it will be.

By not working, I meant that I saw zero watts on the status panel. The plugs were fully seated and the only variable I changed was the extension itself. If you’d like to experiment with them, I’m happy to donate to the cause. I doubt the ebay seller would take returns and I can’t be bothered anyway.

If the Amazon cables don’t work, I’ll give those you linked a try.


That tells me that the extensions are simply defective. Seems unlikely, but nevertheless it’s a simple device and would work somewhat. What seems puzzling is the allegation that they work as an audio extension but not for a CT.

The only thing I can imagine is that perhaps some of these are crossing the left and right channels. That would exhibit the symptom you are reporting. If you want to send me a failing extension, I’ll verify and diagnose.

IoTaWatt, Inc.
PO Box 1679
Wolfeboro, NH 03894

I’ll put them in the mail this week.

Ordered and installed 4 extenders from Amazon. All of them worked.

JacobsParts 10-Foot 3.5mm 1/8" Stereo Audio

AmazonBasics 3.5mm Male to Female Stereo 6 ft 3.5mm Stereo Extension Audi

KINPS Audio Auxiliary Stereo Extension Audio Cable 6 ft 3.5mm Stereo Extension Audio

I also ordered 1 I didn’t install (or test) and haven’t linked here. What I like about these 4 is that the cables are thin and the plugs small. I might have been able to run all my cables through 1 3/4" conduit if I had used these extenders from the start. They were super easy to fish through.

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Got the cables.

All four had the right and left channels (tip and ring) crossed.

One had no continuity in the sleeve.
One had a short between the sleeve and tip.

So those two should not have worked for audio (one would pass one channel).

The other two, when connected together, actually worked as the first reversed and the second corrected.

Bottom line, very poor quality extensions.

Thanks for following up. Interesting to know what you found. It cost me nearly as much to ship the others back to Monoprice as I’m getting refunded, but I hated to just through them in the trash. If I were to do it again, I’d just buy from Amazon, knowing I can return without questions.

Do you have a source for tested Y splitter?

Sorry, I do not. I had bought some on eBay a year or so ago and they were fine. Given they are short, I wouldn’t worry about resistance. The key factor is that the left and right channels aren’t switched, which will not work.

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Im using several kinds from Amazon. Both work well.

These are kind of pricey but flexible. about 12 inch long.

If you have these plugged into both sides of the IotaWatt it make the IotaWatt footprint much wider.

I you have these plugged into both sides of the IotaWatt it make the IotaWatt footprint much wider.