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In my professional life, I work in datacenters and all of our PDUs have ammeter displays on them.

Of course they do: we always want to know how many amps a PDU is using.

But in my house, nobody has any idea. As far as I can tell, there is no such thing as a breaker panel, distribution panel, or anything else that has any metrics whatsoever.

This is weird, since I am constantly interested in how many amps either a particular circuit or subpanel is using—or even my entire house, for that matter. I am always looking for this data and have no way to get it.

I don't want to hang a clamp off the wires, and I don't want to take manual readings of circuits or wires. I want a proper ammeter with a real-time measurement.

How can I do this?

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    I have one of these installed at home. If you want to talk about it more, @ me over in the chat room. It monitors 32 separate breakers and monitors voltage, temp sensors, and pulse meters. – JPhi1618 Nov 14 at 19:05
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    You could design an ammeter that snaps into a 2-pole breaker space. Wouldn't hurt to partner with Eaton, they know how to make the clips that'll fit every modern breaker line: in their BR, CH, CHQ and CL. – Harper - Reinstate Monica Nov 15 at 5:35
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    Generally you'd use a induction-style ammeter that clamps around the "hot" wires, similar to the portable "clamp-on ammeter". It is necessary to have the individual wires separated to do this, but they do not need to be cut or stripped. – Hot Licks Nov 16 at 0:01
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You're going to careen headlong into

NEC 110.2. All equipment must be approved.

You want a conductive ammeter. OK, because of the exigencies, that's going to be a large enclosure that will need to mount past your main breaker. You can't insert that between your main breaker and buses in your panel, because your panel isn't listed for that. That means changing to a meter-main outside the house, connected to the conductive ammeter equipment which is UL listed for this use, connected to your former main panel, which will need neutrals and grounds separated.

"But you only need an ammeter shunt" all of the above applies to the shunt housing.

The ammeter equipment won't be cheap, because it'll be low production rate equipment made for industry. I would expect it to be a triple ammeter intended for 480V, which is fine; use the third meter for neutral. Are you sure inductive meters won't suffice?

Nothing wrong with induction-based ammeters for measuring the current of a known frequency.

Which is to say, there is no reason to doubt ammeter readings merely because they clamp on.

As such, a variety of consumer products provide exactly what you are looking for. The units are UL listed, obviously; they sit inside the service panel with clamps on the supply and also on some number of branch circuits. The only thing that sticks outside the panel in a knockout, is a WiFi antenna. Which elegantly solves another code problem, keeping mains and low voltage systems rigidly separated.

That is the way to go. The existence of these products will deter anyone else from offering plain old hardwired ammeters at a consumer price.

  • Thank you. I don't think there is anything wrong with induction monitoring, I just want a clean and well-integrated installation. I really don't understand why a cheap, totally uninteresting rackmount PDU can very easily display AMPS/Volts/etc. but there are not ready-made panels, or panel modules, that provide this. I also don't understand why everyone is not demanding this - I am not doing anything particularly interesting, and yet I am looking for these numbers all the time ... – user227963 Nov 14 at 19:31
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    @user227963 -- gizmos like the Sense are probably your best bet then, even if the IoTy interface is somewhat offputting to you at first. – ThreePhaseEel Nov 15 at 1:15
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    @user227963 Approval. Approval is not only when everything is working properly. When electrical problems happen, how does the equipment fail? Does it light up and burn your house down or does it contain the external problems? If it internally fails what happens? You're thinking it is simple because you're only thinking of when everything is properly setup and working. Regulators need to make sure it doesn't kill anybody when things go south. – Nelson Nov 15 at 3:44
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    The PDU handles 1/10 the power (20-30A vs 225A). The PDU might be entirely unrated (things from China, eBay, Amazon Marketplace evade safety regs) or if rated, it uses "RU" listed electronic components (e.g. sold by Mouser). Mains devices must be "UL" listed equipment, a higher standard, and service panels are the highest tier of all. And all it would give you is 2 meters; whereas a Curb, Eyedro, Neurio, Sense etc. give you 2 meters on your phone and you can check it from Kazakhstan. – Harper - Reinstate Monica Nov 15 at 4:57
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    As for why people don't care, it's almost never an issue because of the provisioning strategy required by NEC, which makes tripping a main breaker highly improbable. If they are worried about loads, the "safety valve" sort of buying a Sense is just look at the meter. It indicates kw usage easily enough. You are sort of asking an XY question here; what's your need? @user227963 – Harper - Reinstate Monica Nov 15 at 5:01
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Check out the Sense Energy Monitor -- it does use clamp on ammeters, but they're meant to be permanently installed. Other than that, I think it would meet your requirements.

  • Terribly expensive for only two sensors, no? $300. Wow. I did a quick google search and found sensors for ~$12. I would be tempted to design and install a custom system with these sensors and a raspberry pi and perhaps an off-the-shelf ADC/mux module. This would be an interesting and fun project if one has the skills... – peinal Nov 15 at 23:15
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    See @Nelson's comment on Harper's answer about approvals -- that's how you get from $12 to $300 when making it into a commercial product. – Nate S - Reinstate Monica Nov 15 at 23:36
  • sure. But, you don't have to use a commercial product. – peinal Nov 16 at 0:56
  • @peinal But then you have a homebrew pos that isn't safe There's a lot more going on than just 2 sensors. Anyway if you are capable of designing such a thing, your time is worth way, way, way too much to actually do it! – Harper - Reinstate Monica Nov 16 at 2:33
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    People have to think about failure modes. Electricity will kill you and take your family with it. You want to save $300 and risk your family? – Nelson Nov 16 at 3:27
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I recently looked into ways to monitor my solar panels and my home's power usage, so I've got some experience with this.

Can you get the parts to do this? Absolutely.

Here in the UK, our breakers are in a 'consumer unit' with the breakers mounted on DIN rail - and the suppliers of industrial parts can supply DIN-rail-mounted power meters - such as this DIN-rail-mounted digital power meter:

DIN-rail-mounted power meter

However, I opted not to do this because in my country, any modifications to the consumer unit have to be signed off by a qualified electrician, due to a spate of fires caused by incompetent electrical installations. As putting an industrial power meter into a residential installation would be an unusual thing to do, I felt it would be challenging to find someone inclined to be adventurous in what they sign off.

I also had access to some other options - such as a wireless home energy monitor:-

Wireless home energy monitor

I know you say you don't want to hang a clamp off the wires, but this was the option I went for, as it was a heck of a lot cheaper than getting someone to sign off something fancier. And being wireless, you can watch the readings from elsewhere in your home - in my case, I connected the receiver to a computer to record my power usage. However, I remain sceptical about magnetic clamps as a means of sensing, having seen it give nonzero readings before I'd even put the wire into the clamp.

My country also has smart meters with in-home displays - made mandatory by the government, and installed at the power company's expense. So it could be worth checking if your country has a similar scheme. Unfortunately, the smart meter supplied by my power company was pretty useless, which is why I ended up with the current clamps I mention above. Here's a picture of some similar to the ones they supplied me with:

Smart meter and in-home display

Finally, many electricity meters in my country have an an LED that flashes at a rate proportional to energy usage - you can buy an optical pickup that will couple onto those. Unfortunately this didn't meed my needs for solar energy monitoring, as a single LED couldn't give info about electricity import and export at once - but it might work in your case, and they avoid both current clamps and the need to rewire your breaker panel.

Optical pulse energy sensor

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There are a few options like that available for residential use.

  1. Something like the Sense Monitor. It has two clamps that wrap around the supply coming into the panel, and monitors the amperage used there. It also has all kinds of smarts to figure out based on usage patterns which circuit is currently drawing and how much. I'm sure there are other devices like that from other manufacturers out there, this one is just pretty prolific so it came to mind right away.
  2. Leviton has released a load center and a line of "smart breakers" with an accompanying app. This looks like it allows you to view real-time information as well. I think these breakers can also be shut off through the app etc.
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There are small inexpensive devices for sale called "Kill-A-Watt" that you can plug into an outlet, then plug in your appliance / device and it will tell you the watts, amps etc. that the device uses. I find them very handy to snoop out power drains. For the Whole House, there is a system called a TED (The Energy Detective); more expensive than a Kill-A-Watt unit, but it looks at your entire house and specific loads and can talk to a smart phone. It also requires removing wires and connecting to breakers, so for some, that means hiring an electrician.

  • The Kill-A-Watt only covers a single outlet, and only handles 120V, 15A service. If you want to know about your 240V, 20A air conditioner, your split-voltage dryer, or your hardwired ceiling fan, you're out of luck. – Mark Nov 15 at 21:48
  • @Mark you can push a Kill-a-Watt to 20A, but it will squeal if you do. Literally. I did not know those things had speakers. – Harper - Reinstate Monica Nov 16 at 21:07
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You may want to take a look at the Socomec Multifunction Meters. Industrial grade multimeters that provide current, voltage, power, max values and average values and can be installed into the circuitry of your panels.

You can attach communication interfaces to it, so the multimeter provides data in Profibus, Modbus and IIRC ModbusRTU

(I am not affiliated with Socomec, but developed the communication interfaces that can be attached)

  • Hello, and welcome to Home Improvement. Good answer that avoids being "spam": thanks. And, you should probably take our tour so you'll know how best to contribute here. – Daniel Griscom Nov 15 at 17:19
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Many "clean" options exist, but they will require slipping (non-clamp-on) current transformers over the conductors in question, and for the main feed that is a job where you probably want the power company to [shut off your power / pull the meter] while you (or your electrician) do it.

I have a Murata ACM20 unit on my well circuit, though I cannot recommend it very highly, as the readout died after a couple of years - though the current transformer itself is probably fine (very little to break there) and may work with some other readout method. Was nice to have when it worked. Not associated, just a considerably less than utterly happy customer.

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