Opened the panel and not what I thought

So, I received my IoTaWatt today (Yeah), thanks @overeasy for the great product. I’m looking forward to using and reviewing it in the future.

However, when I cracked open the panel to have a look, it was not what I expected it would be. I assumed (wrongly) that the mains would pass into the panel and through the main breaker and from there I would find cables to attach the 200A CTs once the breaker was off; along with adding my box and placing the other CTs on the smaller circuits. It appears that the mains drop into the breaker and on the other side of the breaker are the bus bars with nothing to attach the CTs too. I assume these need to be placed on live wires, making sure they are high and out of the way from the metal bottom connectors. Is this standard for most US panels?

Here is what my panel looks like, and it is nowhere like the one from our Aus. friend. That one was very unique and interesting, thanks for sharing.

The closeup below makes me want to attach the CT’s above the 100A Barn Sub Panel snaking its way from the top down.

I wish there was space lower down the cabinet but the existing plush take up the only open space below. On the right, it is hard to see, the panel it too close to the wall to place anything on that side.

The knockout I’m planning on using will be right below the large gray (Barn Sub Panel) on the left. I need to drill a new 1" hole below it as there are fewer things to get in the way. No space from above or below as these are already used up.

Slow, steady, and safe in this situation. No rushing to get to the cool graphs and charts.

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Yes, it is. The mains are typically an integral part of the panel and connect directly to the main buses.

They do seem to do things differently down there, but also, that’s three-phase which is more complicated.

There’s not much room in there. Many panels have a loop on the main cables that are easy to connect to. You don’t have very much room at all. It might make sense to cut that wire-tie and move the sub-panel cables out of the way completely. I can’t tell how much room there is between the main cables and the back of the box. Those ECS24200’s might be hard, or even impossible, to fit in there. If you would like, I could send you some ECS25200’s, which may fit better.

With the breaker off, the two metallic connectors on the top of the breaker will still be live, and so a shock hazard. I would encourage you to have an electrician install the CTs.

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This is what I’m thinking on the mains as that gets outside of my comfort zone. Assumed I would be able to disconnect and attach below the mains breaker. I’m not sure why the electrician who did the barn panel took up so much space with the loop.

I also assume that the 100A and the cable in the panel will be too big to do the loop for one of the phases. Is this one that would be better off with two CTs or can we put one on and double it up in software?

With the breaker off, the two metallic connectors on the top of the breaker will still be live, and so a shock hazard

Agreed - the wiring behind my box needs a cleanup but nothing is exposed and its relatively safe. Yours scares me a little.

Me too. :slight_smile: Yours for me to see was fascinating more than scary.

US is 110VAC so the side effect is they need twice the current for the same watts output. i.e. a 2000W kettle here is about 8A so the US is probably close to 18A. More copper required too.

Once had an American visitor here, he commented how much faster a kettle boiled here.

Why the huge earth cable? Someone expecting large currents or is this some sort of “earth return” system?

I may be a geek around numbers and also likes seeing other ways electricity is done around the globe, and this tool and community give me the ability to fulfill both. :slight_smile:

No sure why the large earth/ground as the system was installed in the home when it was built in the 70’s. We have only been in the home a few years ourselves. Like others, we are also learning that there is quite a few “home owner” specials with both the electrical and other aspects of the house. We were told the previous owner was quite the “handy man”.

I agree with you on the unique US split power and the extra effort and amperage required to get things heated up. I’m sure the different ways of supplying power in parts of the country make it interesting for product makers having to support both, and don’t get me started on all the different plug types.

Somewhat off topic, but thought some may enjoy it.

One funny (sort of) story we discovered about our house was that when you are down in the basement on the concrete floor without shoes and touch anything metal, you get a slight shock (24v-48v); like touching a 9v battery to your tongue but on your skin.

We had an electrician out who conformed what I already knew but was unable to find where the odd power source was coming from. When he disconnected the mains via the breaker, the phantom power continued to be present. We had our local power utility come out with all their magical tools and technology and tell us the same, he was seeing this same voltage in the ground and also when touching objects like copper pipes, etc.

He disconnected our house from the street pole and the phantom power still remained. He told me we either had a buried alien spaceship creating power (good for us), or it was back feeding through the cable company which also provides us with phone over their cable. When the cable company came out along with the power company, they found that the phantom power goes away when you have the house power disconnected and the cable disconnected; go figure, no space ship then.

We were told this is not a hazard (unless in the basement with no shoes and touching something metal), and to simply add a larger earth outside (not in the box) along with new grounding rods. We were told this would force the phantom power to the ground and it would be less noticeable. After driving two 9’ brass grounding rods and attaching them with heavy ground cable to themselves and the main panel, we still have the phantom power which they suspect is from the neighbors house built in the 1600s.

I guess some of the things we all have to deal with being home owners keeps life “fun” and interesting.


The ground is the smaller bare wire. The neutral wire is the big bare wire. It is connected to the center tap of the transformer at the street. It is also connected to the ground wire but only at the service entrance. The two hot wires have a nominal 240VAC between them and 120VAC between each and the neutral/ground. Unlike three phase power (where the phases are 120 degrees) the two hots at 180 degrees apart, so not technically called phases. In multi-family dwellings, it is fairly common to provide two of the three phases to each unit. This provides less voltage, 208VAC nominal and the legs are now 120 degrees apart instead of 180. This makes it complicated for measuring power with only a single voltage reference as most products do