Current Sensor basic questions

IVB

IVB

Senior Member
I want to ensure I turn the dishwasher on before I go to sleep. Because apparently I suck at it. 
 
Do I just go get any of a bazillion non-invasive current sensors (ie https://www.amazon.com/gp/product/B005CTWE8A/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A1THAZDOWP300U )
 and put it around the cord?
 
I saw some posts that said I needed to open up the 3-wire (or rather, use a small extension cord and butcher that), isolate the hot, and put the sensor around that.
Q1) Is there any fire concerns with that? Seems a little odd to be splicing up a factory made wire.
Q2) Do I just get any regular small 3-prong extension cord or is there a special type?
Q3) The sensors all seem to have a 2.5mm or 3.5mm output plug. I assume I just cut that off and run into an Elk zone?
Q4) The dishwasher runs on a 15A circuit. Some of these sensors are rated at 30A, 50A, or even 100A. But they're all relatively inexpensive. Does sensitivity vary as you get into higher amps (or cheaper price)?  Would it matter if i'm just looking for a boolean on/off, rather than measuring consumption?
Q5) Are there super high sensitivity current sensors in case I want to monitor a very small load, ie just a few amps? Its harder than I thought to find that info.
 
Thx.
 
IVB said:
I want to ensure I turn the dishwasher on before I go to sleep. Because apparently I suck at it. 
 
Do I just go get any of a bazillion non-invasive current sensors (ie https://www.amazon.com/gp/product/B005CTWE8A/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A1THAZDOWP300U )
 and put it around the cord?
 
I saw some posts that said I needed to open up the 3-wire (or rather, use a small extension cord and butcher that), isolate the hot, and put the sensor around that.
Q1) Is there any fire concerns with that? Seems a little odd to be splicing up a factory made wire.
Q2) Do I just get any regular small 3-prong extension cord or is there a special type?
Q3) The sensors all seem to have a 2.5mm or 3.5mm output plug. I assume I just cut that off and run into an Elk zone?
Q4) The dishwasher runs on a 15A circuit. Some of these sensors are rated at 30A, 50A, or even 100A. But they're all relatively inexpensive. Does sensitivity vary as you get into higher amps (or cheaper price)?  Would it matter if i'm just looking for a boolean on/off, rather than measuring consumption?
Q5) Are there super high sensitivity current sensors in case I want to monitor a very small load, ie just a few amps? Its harder than I thought to find that info.
 
Thx.
Click to expand...
Here's one where you don't have to separate out just a single wire:  https://moderndevice.com/new-products/current-sensor/
 
currentSensorWplug.jpg

Instead, you can simply hold it snugly against the cable with zip ties.  That makes it different as compared to all the others, which require you to either break a wire to insert an inline sensor or separate out a wire.
 
It should be easier to monitor at your electrical panel as you likely will have a dedicated circuit for the dishwasher.  If not, you'll have to split the cable as the current clamp needs to go around a single conductor.  The one you linked to outputs 0 to 1V in proportion to the current flow.  I'm not familiar with the Elk so don't know if it has analog inputs that can measure that directly.  If you want a boolean signal, you may need to use an intermediate circuit.   There are many different kinds of sensors available with varying levels of sensitivity and accuracy.  Also, some come with an integrated burden resistor and some do not.  Be very careful with ones that don't have one as they can produce dangerous voltages
 
If you are interested in monitoring other circuits, you may want to consider something like this: http://www.brultech.com/greeneye/ or you can use these to measure two circuits each: https://www.amazon.com/Aeon-Labs-AEDSB09104ZWUS-Aeotec-Monitor/dp/B00DIBSKFU/
 
Cheers
Al
 
Do you have any automated lighting or do you set your alarm stay mode at night so that you can trigger an audible reminder off of one of those when you shut things off to go to bed? Or maybe a motion detector placed strategically so that it reminds you when you go in the direction of your bedroom after a certain hour.
 
Mike.
 
Easiest of all is to just plug it in as a pass-through to an energy monitor. such as:  https://www.amazon.com/Aeon-Labs-DSC06106-ZWUS-Z-Wave-Smart-Energy-Switch/dp/B00I7EVJ88/ref=sr_1_10?ie=UTF8&qid=1466519255&sr=8-10&keywords=z-wave+energy+monitor
71YblGSKRoL._SL1500_.jpg

It could easily monitor a dishwasher or a washing machine.  I happen to use these, and they work fine.   You can often get them at $25 each (prices on Amazon fluctuate).  Not sure if your system speaks z-wave, but there may be similar devices for other protocols out there.  
 
The sensor linked in the OP goes around a wire.  It you put it around the whole cord the current to the load in one wire cancels the magnetic field in the wire with current from the load.  Thus you need to break out just one of the wires and put the sensor around that.  Some people put this type sensor in the power panel although there may be code issues with that.
 
They wires are separated in the dishwasher so this sensor could be placed in the dishwasher itself.  They aren't usually plugged in so an extension cord solution seems like a lot of extra work for nothing - put in a receptacle, use a short extension cord and put a plug on the dishwasher.
 
This sensor is a current transformer and outputs an AC voltage.  It likely needs some circuitry to generate a signal usable with the Elk.
 
You don't want a sensor rated for a lot more current than you have - the sensor may not detect the lower current.  If you do have low current you can pass the wire through the sensor several times to increase the field the sensor detects.  Multiply the actual current by number of passes through the center of the core to get the current the sensor detects.
 
The sensor board that IVB posted also senses magnetic field but does it a little differently so that the sensors can pick up the field from each wire.  The board would need to be moved around the wire to get the placement relative to the wires in the cord for best sensitivity.
 
There are also ways to monitor a light on the front panel.  I think the posts may have been to monitor a water heater...
 
How about a relay wired into the dishwasher that outputs a contact closure?  RIB (Relay in a Box) makes them in an easy to use package.  Easy hookup to the Elk too.
 
What you really want is a current sensing switch, rather than a current transformer which gives you a voltage output proportional to the current flowing through it. That's not very useful to connect to the Elk.
 
The RIBXG that BSR linked to is exactly what you want.  Another option for a current switch is a Veris Hawkeye H800. 
 
Dishwashers are usually connected directly to the house wiring through a junction box, which may be behind the kickplate of the dishwasher, or external to it in an adjacent cabinet or in the wall.  There's a good chance you could fit the current switch inside those boxes.
 
You want a sensor that can sense a low amperage.  The RIBXG and Hawkeye can sense as low as 0.35A and 0.25A, respectively.  That's about right for the dishwasher.  But if the current drawn by the dishwasher is too low to trip the sensor, you can loop the wire through the core multiple times to increase the signal.
 
RAL said:
The RIBXG that BSR linked to is exactly what you want.  Another option for a current switch is a Veris Hawkeye H800. 
Click to expand...
 
That's a good alternative.  Once difference I noticed though was it doesn't seem to have a split core (would require disconnecting a wire, then feeding it through).  Not that big of a deal.
 
IVB said:
I want to ensure I turn the dishwasher on before I go to sleep. Because apparently I suck at it. 
Click to expand...
 
How is a current sensing device going to remind you to turn on the dishwasher before you go to sleep? It is only going to sense current after you turn the machine on.
 
Mike.
 
Wow thanks for all the replies, looks like i have some serious homework to do. I'll likely buy both the RIBXG (once I determine which sub-model) and the zWave to see which works better.  The dishwasher isn't on a dedicated circuit although the only things on it are the disposal and 2 60W bulbs so that'll work. Monitoring at the panel=electrician, whereas I could do a regular split core sensor myself. I can use 
 
Re:How will this remind me, our standard practice is to arm the security system once we're in bed via the Echo ("Alexa, tell Jarvis to arm stay mode"). CQC already sets the echo reply with "doggy door open don't forget to close", so I can just append this to the reply ("and you didn't turn on the dishwasher dummy"). I can't use a motion sensor as we move back & forth a million times, kitchen is right next to our bedroom. Its a single story living area.
 
This seems silly, but how do I actually wire a RIBXGF? My dishwasher actually plugs into a dedicated outlet box under my sink.  I was going to take the outlet out of the box, clamp the sensor around the hot wire, and then cam it all back into the box.  But do I just drill a small hole in the side of the box that the low voltage wires from the RIBXGF come from?  I guess I don't like mixing LV and HV in the same box and that makes me nervous.
 
Mike - I don't have mine installed or programmed yet obviously, but I was going to set it so when I press my "Good Night" light scene it will check to see if the dishwasher is running or ran recently.  If it is then all good.  If not then it will maybe flash the light or beep my keypad.  I could easily set it up to check when I arm my system to night mode.  Or check when I arm it to stay after 9PM.
 
Install a second box. If the box is inside the wall, use a extension ring and use a nipple to another box for the LV.
 
What Del said.  Many of the RIB devices can be wired similarly.  I wasn't sure how to separate the LV and HV at first but that seems to be the intended way.  Put two boxes (and an extension ring if needed) together with a very short conduit between. In my case I was using a RIB-U1C which mounts on the side of the box with wires going into the box.  The low voltage wires go through the HV box into the LV box.  From there you can splice on other LV wires.  The LV wires may not need to be in a box but a box looks cleaner and provides some protection of the splices from damage.  The general rule, as I understand it, is that the LV wires in the HV box must have insulation rated for the higher voltage or have a secondary separator (wall, tubing, etc) that maintains clearance.  There is no HV in the LV box so the wires going out to your automation system or such like only need to be low voltage rated wire.
 
Or you could clamp the sensor on a wire under the dishwasher.  Most I have seen have open wiring in the base.  But this does require pulling the unit out. 
 
Obviously (or perhaps not), you need to assess the safety and code compliance of this for yourself. 
 
At the risk of starting a firestorm of posts against this method, I offer the following:
 
Get an extension cord like THIS and just carefully cut between a small section of cord to separate the wiring with an X-Acto knife.  The insulation is left intact and you can just use the open clamp to clamp around the end conductor. 
 
Instead of this you could just get a plug and re-terminate that end after you separate the wiring.
 
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