[HH] instrumenting a breaker box

[Greg London]

> What are you looking to sense? When current is flowing through a
> breaker? How much current? How much voltage? Both?

We moved into a different house last fall and our
electrical consumption is about double our old house.
Was trying to figure out where the power is going.

The new place has mini-splits: electrically powered
heat pumps which provide heat and AC. Wondering how
much power they're chewing up. and if they're cheaper
than oil...

On Wed, October 22, 2014 3:30 pm, Tom Metro wrote:
> Greg London wrote:
>
>> Was looking to instrument the circuits in my breaker box.
>>
>
> What are you looking to sense? When current is flowing through a
> breaker? How much current? How much voltage? Both?
>
>
>> The only thing I could find commercially was this:
>>
>>
>> http://www.theenergydetective.com/
>>
>
> There's also one of these:
> http://www.bluelineinnovations.com/
>
>
> I bought one years ago for some trivial amount when NSTAR was
> subsidizing the cost, and unfortunately never got around to installing it
> (which I still should), so I can't speak to its effectiveness.
>
>
> It has a consumer-friendly sensor that simply clamps onto your
> electricity meter and optically monitors the spinning wheel or digital
> display to track power usage. (Seems rather inefficient when you can
> probably get that info directly from the meeter with a bit of RF hacking,
> as the new meters can be talked to wirelessly.)
>
>
>> But that only instruments the incoming circuit...
>>
>
> I'm pretty sure one of the newer startups doing this claimed that with
> some analysis of your usage patterns, they can figure out how much power is
> going to each of your major appliances, despite only having a whole house
> sensor. Seems a lofty claim. Or maybe they were just claiming that after a
> learning period, they could tell you which combination of appliances were
> running at any given time.
>
>
>> (200 amp service, 40 circuits)
>> ...and getting enough sensors to do all the breakers
>> could cost close to a thousand dollars.
>
> A current probe for a multimeter will run you about $40:
> http://www.amazon.com/Current-Clamp-Probe-for-Multimeter/dp/B00NRHB5PM/
> http://www.righttoolusa.com/p/Tpi-A250-Ac-Amp-Current-Probe-Adapter-400a-F
> or-153-163-183-183a-And-31258602.html
>
> which would add up to $1600 for 40 circuits just for the probes.
>
>
>> Seemed expensive.
>>
>
> Like Drew said, probably pretty reasonable for a code compliant solution
> that you can install yourself.
>
> Code-wise, there's probably more flexibility if you are installing the
> probes outside of the main breaker box. Something you'll want to consider
> if you go the more D-I-Y route suggested below. Obviously the probes are
> low-voltage and electrically insulated from the power wiring, so they are
> low risk. The challenge is that the probe needs to be placed over the hot
> wire only, so you can't just clamp it onto the romex cable in any old
> spot. Splitting open the jacket at a mid-point would undoubtedly be a code
> violation, but you could do that inside a small work box. Consult an
> electrician.
>
>
>> Anyone know of a cheaper way?
>>
>
> You can easily find multimeters with integrated current clamps for as
> little as $12:
> http://www.harborfreight.com/digital-clamp-on-multimeter-95652.html
> http://www.amazon.com/Meter-Multimeter-Digital-Clamp-Probe/dp/B00E6NDZ22/
>
>
> (That a probe alone cost $40 and a probe + multimeter only cost $12
> probably tells you something about the relative quality.)
>
> But you'd have to do a lot of hacking just to get the mechanics to work.
> And that's before you build whatever is necessary to process the signals
> from all the probes.
>
> It looks like there are some lower cost current probes made for home
> automation:
> http://www.amazon.com/s/ref=nb_sb_ss_c_0_14?url=search-alias%3Delectronics
> &field-keywords=current%20sensor&sprefix=current+sensor%2Caps%2C382
>
>
> Here's one that is good for up to 30 A that will only run you $7:
> http://www.amazon.com/Current-SCT-013-030-Non-invasive-Split-Core-Transfor
> mer/dp/B00L51AD3W/
>
> One good for 120 A for $12:
> http://www.amazon.com/0-01-120A-0-5M-Split-core-Current-Transformer/dp/B00
> 5FIFT4E/
>
>
> and it looks like there may be some interface boards designed to glue
> these to an Arduino or something, but all you should need is an A-to-D.
> (See user reviews on the last one for some tips on attaching it to an
> Arduino.)
>
>
> These are all "split-core" probes - meaning the coil opens to be placed
> over a wire. For your branch circuits, you might be able to save by using
> coils that don't open, like:
>
> http://www.amazon.com/Leviton-CDA02-L12-Sub-Metering-Current-Transformer/
> dp/B0055D6F92/
>
> One of the Amazon Merchants is selling that particular one for $10,
> which isn't really a bargain, but I bet similar coils could be found for
> under $5. The savings trades off for higher installation effort, as you'll
> have to remove the wire to each breaker to install it.
>
>
> Another option to investigate is whether you can get a breaker with
> integrated sensors. Such a thing might not exist for residential
> applications. But if it did, you'd end up with a much cleaner
> installation. (Some modern circuit breaker designs use current sensing
> electronics instead of the old style thermo-magnetic design. So a lot of
> the hardware you'd need is already in the breaker.)
>
> At one time SquareD (now Schneider Electric) had a line of breakers that
> fit their QO family of panels (stay away from the lower-end Homeline
> panels) that facilitated remote switching of the breaker. I don't recall
> what sensor information it provided. I don't spot anything like that on
> their breaker page now:
>
> http://www.schneider-electric.com/products/us/en/50300-circuit-breakers/
>
>
> And they do have a remotely operated breaker made for lighting panels:
> http://www2.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/cont
> ent/live/FAQS/228000/FA228072/en_US/1210CT0201.pdf
>
> but it's a pretty old-school design using a motor to mechanically move the
> breaker, and no sensors.
>
> The breaker replacement approach, even if you can find then, is unlikely
> to be cheaper. You'd probably have to start by replacing the whole panel
> and the material costs would likely be twice what regular breakers would
> run. ($1000 for a typical panel replacement parts and labor, so $2000+)
>
>
> -Tom
>
>


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