Interested in buying...some unanswered questions?

I’m interested in getting an IoTaWatt, it looks like the best “no cloud” solution out there.

First question, I keep all my IoT and home automation stuff on an isolated VLAN that can only talk to my HomeAssistant server, and basic network resources (pfSense router running DHCP, NTP, limited inbound-only-access from my PC to configure devices).
Are there any issues I would expect with an isolated configuration like this?

Second question, I have a LOT of circuits in our panel (its completely full)…single-phase 200A main, 1x 240V generator interlock circuit, 7x 30-60A 240V appliance circuits, 5x 120V “single breaker” circuits, 18x 120V “half breaker” circuits. I know I want to be able to track some things (e.g. both furnaces to know when aux. heat is on, washer, dryer, sump pump) to drive automation in HomeAssistant, but are there suggestions how to decide what I should/shouldn’t pick and what circuits to ignore? Can I loop a CT over say 3-4 adjacent 120V breakers and get an accurate combined reading?
I do know what is on every breaker (about 3 pages of bizarre mismatched mix of rooms) but I have a hard time deciding if I actually should bother with many of them - e.g. “all the bathroom outlets”…or one breaker is “just the kitchen lights” another “just the smoke alarms”.

I’m attempting to attach a picture of the breaker box I snapped when the electrician was wiring up the generator…to get an idea of available space and wire density (bearing in mind 2 of the biggest circuits are not connected to their breakers yet in the picture…they are now).

I also have concerns that there isn’t enough room for 1 CT per circuit (especially on the half-breakers) and I worry with so many wires it may be difficult to get the wires out of the box to the control brain(s)…especially if I end up waiting for the model that has more inputs or get more than one? What’s the usual way to get all the wires out - how many will fit thru the couple remaining 3/4" knock-outs in the bottom of the panel box that are unused?

I understand one of the power bricks us used to tell “voltage”. How does this work with imbalance between the half-phases? I see sometimes ~1V or so difference between the L1/L2 to neutral, will that affect the readings?

Finally gather it also requires 2 power bricks, one for power one for voltage sensing. Is there any way to reduce this down? My panel box is in my garage, and there is exactly 1 duplex outlet for the entire 2-car garage. Its also a GFCI so I can’t put a multi-tap cover on it because the screw hole is in the wrong place and covers buttons…and with the box full its going to be very hard to add more outlets by the box. I don’t suppose there is some way to use a single wall-wart for both power and voltage sensing? Or could I make a “Y” cable that can rectify and step down the “sensing” voltage to power the board off the one wall-wart?

Deciding which circuits have priority is easy. Its the ones that cost you money and the ones that make you money, solar for example. Typically heating and large motor circuits can cost a wad of cash. Light circuits, unless you have a lot of 250w linear tubes on them probably aren’t high in the list. Power circuits with low loading could also be ignored. You will need CTs for your mains connections (2 I assume) and from those and the other monitored circuits, you could use IotaWatt’s derived values to calculate the “non monitored circuits”. For example I have 2 AirCons. A large one (2.4Kw input power) which runs most of winter and uses the bulk of my power during that period and a little one (1Kw input power) in my bedroom which might run 40 hours a year. I don’t bother metering the little one.

A 3/4" (19mm in Aus) gland will accommodate a large number of CT cables. Eventually the size of the 3.5mm jack becomes the limitation. I have 11 ATM but I think another couple could be squeezed in.

You could try a “y” cable with a simple 5V power supply on one leg but if it caused any phase shift of the “other” 9V AC leg, that would impact the wattage calculation. Noise bouncing back into the AC leg could be an issue as well. You can’t you just screw a simple multi socket power board into the wall beside the GPO?

That’s a lot of questions. Only you can decide what you want to monitor, but monitoring the big things is good to do. I have two IotaWatts and that is not enough for all the circuits in my panels. But, I started with something that only had 7 channels and only one before that. You can learn a lot by looking at the mains. Having big things on individual channels makes it easy to tell how much they cost. Since I don’t have enough channels, I put things that have very different signatures on the same one. That makes it easier to see what is going on.

I have four 1/2 conduits from my panel to the box for the IotaWatt. It is not enough for the big wires and big plugs that the CTs in the store have. I have some older CTs that have thinner wire and no connectors. They can easily hold 6 cables. 3/4" conduit can hold more. Your panel does not appear to have a lot of free knockout’s either at the top or bottom. Mine has lots of space at the bottom. There is a large knockout on the top that might work for yours. Use 2" or so conduit. That should be big enough for all your needs.

Use a power strip for the VT and the power supply and you will have extra outlets for whatever else you need/want.

Yes, there can be a difference of a volt or more between the legs. Bob has an article about using a 240V circuit and the 240V VT, or you can pick one of the 120V ones and it will be slightly off when the load is off balance, but mostly right most of the time. This is the reason I have 2 IotaWatts. I have one for each leg. It is not necessary, but I wanted the extra channels and also to prove what the inaccuracy really would be. It is generally within 1-2%, so having a single VT is fine.

Maybe, but I was also hoping to have power strips elsewhere for emergency light, tools/chargers/whatever I need to plug in; hopefully in the near future might get Starlink internet and probably have to plug in its power-injector there; as well as leaving one socket on the outlet for high power tools (e.g. I have an air compressor that draws 12-14A 120V) that I already know from experience will trip power strip overload protections. Wish it wasn’t a finished garage…and wish there was room in the panel for additional circuits.

Its the one complaint I have about this place and not cheap to do anything about - dunno what nutter thought a single outlet on a single 15A circuit was appropriate for a large 2-car garage in mid 2000’s (garage is where the panel is located). I guess that’s the same nutter who labeled all the 120V circuits “Plugs & Lights” on the panel door facepalm.

Ah…how big are the plugs and wires would you estimate diameter?

I was really hoping to use the bottom of the panel since there is already a hole in the drywall there from the generator install I don’t have to cut MORE holes that way, I’d prefer to keep the holes to a minimum if that makes sense. Also ideally I would like to add shelving and “above” the box is the only way to not obstruct access so putting the sensing brain boxes below would not reduce available storage (I already can’t block it up). Yeah, very tight around this box with so many circuits.

I also notice (annoyingly) the breakers for the furnaces and heat-pumps are on opposite sides so I can’t easily “combine” by looping the furnace+heatpump wires thru one CT (and I don’t think wire is long enough to relocate them but I’ve not yet tried). Also naturally they run out opposite ends of the panel so I can’t snag them adjacent at the top/bottom to combine.

For my overall interest, I don’t care as much about watts as I do relative power…actually I would be quite happy with having just amp-readings…but I would prefer whatever units that it be consistent readings.
I think my interest in monitoring is probably
(1) when is aux-heat vs heat-pump on,
(2) when is washer/dryer/dishwasher running,
(3) figure out if something is abnormal e.g. water heater not turning off,
(4) “what-if” overall picture how balanced stuff is and what my typical usage is for “how many circuits can be on with the generator”,
(5) see any obvious ways to cut down power use

Many panels are different, but you should be able tell from the label or other information what is possible. I believe it should be possible to change one of the existing single full size breakers for a dual one. That can give you a new dedicated circuit for the garage. You might even be able to make it a 20A one. If you have an electrician coming already, it should not be too much extra to do that. If you are planning on doing the work yourself, it is one of the easier installs.

It is, of course, your choice, but I would use the top big knockout to get the cables out of the panel. That is probably the easiest way. Drywall is fairly easy to repair and for a garage does not need to look perfect.

The cables are about the size of standard lamp cord, and the plugs are standard headphone (1/8" plug) size, probably about 1/4" in diameter. Bigger conduit makes it easier to pull and also to meet the maximum fill ratio.

It all depends on how easy to understand you want to make it. Having a system that is broken down by each circuit is great. But, sometimes that is too much detail and not really useful and probably not really interesting (do you really care that your outdoor light comes on 3-5 times a night?).

I have many circuits monitored, but I rarely look at the data anymore. I now know that my peak load is generally within my generators capability. I also know that my heated bathroom floor costs almost $1/day. It’s on my list of projects to have it on less, especially in the summer, when the furnace no longer runs. But, it’s a project and I have a lot more that keep getting added to the list. More than a decade ago, I was really excited about doing something about the floor, when I first figured out what it was costing me. Now I am still somewhat excited about, but still it hasn’t made it to the top of the list of priorities. So, I just don’t look at the data :wink:.

For cutting down power usage, there are two things that can really matter, base load (the things that are always on and large loads). My base load is probably around 200W. I figure that is about $200/year. I have reduced it significantly over time. I had 2 or 3 pieces of AV equipment that were drawing about 25-40W. Since I wasn’t really using them anymore, I just turned them off.

I did measure my water heater and it was using a lot of electricity. So a few years ago I got a heat pump water heater. I have it in series with my old standard one and have it set to heat pump only mode. It saves at least $1-2/day. I got a really good deal on the water heater due to a power company rebate, so it has already paid for itself.

The aux heat uses a lot of power, so it is easy to see from the main power graph when it is on. If you want a programmatically generated report that includes breakdowns for individual loads, having more circuits monitored independently will make it easier to create the report.

So, it gets back to what level of detail you want and how easy you want it to be.

Looks like the double breaker in the lower left is unused. Maybe time to bite the bullet and use it to feed a sub-panel. Going to be an EV in that garage someday anyway.

Actually the 2-pole breaker in the lower left was just installed and is used - that’s the sub-feed from the generator (behind a manual interlock-plate to meet code so you can’t back-feed). It was a significantly less expensive option than a transfer switch but requires manual balancing and load selection.

They had to shuffle around and I believe already installed “half” breakers in all the slots that can accommodate them to free up space for it…they thought they were going to have to put a secondary panel in (which I was told would be around $1500 more) but were able to move enough to half-breakers to fit.

I suppose maybe there’s a way to pull a wire out of the box and have a splice in a single-gang box next to the panel and then split that to the existing “whatever” as well as a new plug…maybe worth considering.

Since we just moved in a few months ago hoping to not have to blow too much more huge bills too soon, when you drop $2K on a water heater, $1K on a generator hookup, couple $K on general repairs, probably need to look at a stove soon…fun stuff. I still have a list to work on :frowning:

I’m not actually sure we could get an EV charger without having the whole panel replaced and higher power feed from the utility company…I hate to think what THAT would cost. My poking about with a handheld clamp meter and turning different things on I observed aux heat alone is 40A+60A if both zones are on so half of the 200A feed before you add in the heat pump compressors/fans (it runs below 35F to keep up). Water heater is 20A, oven/stove 30A, clothes dryer 20A, and I haven’t even started to get into the “normal” other stuff that plugs in (large aquariums+heaters, computers/servers, humidifiers, lights, cooking appliances, etc.) Based on what the power-meter says, on the few very cold (20F) days we push nearly 200kWH per day consumption. Everything here is electric, there is no gas service. Yay…

For the monitor install I’d do it myself…I’m comfortable enough with carefully working around existing stuff (I actually installed CTs and analog meters for the generator circuit to balance the load from “cold and dark”) but I wouldn’t do new circuits and similar myself…if only for the potential liability. Hated spending over $1K for the generator interlock that is only like $200 in parts, but if something goes wrong and sets the house on fire if the insurance complains I can cite the licensed electrician who did the modifications. I’ll do 1:1 swaps and add low voltage probes and such but I don’t like the liability of engineering major changes with higher power on them. I know how to do it, I could do it, I just don’t like doing that stuff as its outside my usual comfort unless I have no choice. Mistakes or oversight can be too costly.

I don’t actually know the base-load here but my crude measurements based on the power-meter readings and math puts me around 2kWH/hour minimum or 20kWH/hour at the upper end. I can read the meter with a SDR and log it (rtlamr) but it only gives me snapshots with poor resolution, I can’t see what the draw is in real-time and certainly not per-circuit like I want.

I know I cut a significant bit off when I got a “power saving” power strip for the AV gear in the TV, according to the UPS its all on that dropped about 150 idle-watts between the game systems, set top players, etc. by having it kill the power to them when the TV is off…only downside is it takes half a minute for anything to “boot up” when you want to use it (which isn’t often). I know my computer rack (homelab server+networking gear) runs around 300W 24x7 because I can read the UPS stats. I hate to think what my WFH laptop is probably chewing up (its a higher end machine 120W brick).

I see with the CT probes the 100A ones are listed as 16mm so that’s about half an inch…would the 200A “mains” ones work on a lower current circuit if I wanted to combine anything (e.g. if I put it around 2 fat wires to HVAC gear)? Or would it not accommodate that in software?

16mm is closer to 5/8”, but no problem using a 200A CT for those HVAC. As long as you do not grossly exceed the primary rating, they all look alike to the IoTaWatt 0-50mA.

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