Combine 2 Circuit into a single reading?

[Gwrapps]

I have several 2-pole circuits in my setup (air conditioners, sprinkler pump, etc) that I have 1 sensor on each leg. I realize I can use just one sensor and double it in the app, but I feel like reading each wire gives me more accurate readings, especially on unbalanced loads.

Is there any plans to allow us to combine 2 circuits into a single reading in the app? It is annoying seeing seeing 2 separate readings for my AC, pool pump, hot tub, sprinkler pump, etc and then having to add them up in my head. Seems like it would be simple to have multiple circuit combine together into a single reading.

[djwakelee]

Summing the two phases is one of the most wanted features (myself also), and yes they state it is planned for a future update (was Spring 2021, now stated to be Summer).  They just did a small update which added nesting of subpanel Vue’s (and other features), so they are actively adding in new things.  Of course, we’d all like it a bit faster, but it is on the list of upcoming new features.

Understand that many 240V loads will be balanced.  A typical 3 ton AC unit, pumps, hot water tank, EV chargers – anything which doesn’t have a neutral wire going to the load will fall into this case.  In those cases, only 1 clamp is needed and nothing is gained with 2 clamps.  However, what makes the present measurement workaround with 1 clamp somewhat inaccurate is that you specify a multiplier of 2x in the app to make this work.  But, if your voltage on each leg is not the same, this is where the small inaccuracy creeps in for the power.  Small error, but possible.  What they really need to do is add the phase 1 and phase 2 voltages, and then multiply by the current.  Hopefully when they add proper support for single clamp 240V they will do this, and then the 2nd phase monitoring is only needed for unbalanced loads or subpanel feeds.

[Trebacz]

I live in AZ and we have heat pump(s) and air handler(s). For simplicity I’d like to combine 2 240V circuits for simplicity of viewing. I only use one clamp on each, but really only care about the combined energy usage of the 2 240V circuits.

[djwakelee]

@Trebacz: Combining two balanced 240V circuits can be achieved 2 different ways by physical clamp setup/hookup.  If you can fit both wires through the 50A CT clamp, you can do that and both circuits will be summed into one channel.   Both wires have to be on the same phase (same hot leg for each circuit) – otherwise they subtract which is not what you want.  If you can’t fit both wires in the the CT, you can purchase their larger 50A CT which will likely work.  Finally, if the wires are far away, you can get a 2.5mm Y adapter cable (audio mono), and combine the two CTs before connecting to the single Vue 2 channel.  You can only do any of these things for balanced 240V circuits – loads which don’t make use of a neutral (like you mentioned).

I do this with my solar production, which is monitoring two different 240V systems (string inverter and microinverters), using the two wires inside a single CT method.  You can do the same thing if you want to combine 120V circuits, which I also do (out of channels – even with two Vue 2’s).  Same story there – the two 120V circuits must be on the same phase.

Hope that helps.

• This reply was modified 2 years, 10 months ago by djwakelee.
• This reply was modified 2 years, 10 months ago by djwakelee.

[charettepa]

this can be done, on unbalanced loads with neutral

but…..

you need some slack in at least one of the 2 load wires

the second phase must be looped and inserted into the clamp in reverse as the current is going in the other direction

 

the only limitations are

if too thick and you cant fit both into 1 clamp

or

if the wire is too short as you cant loop it to reverse it

 

if its too short

1 alternative is to disconnect the 2 load wires from the double breaker

cross the wires

 

going from this

1=============1
=
2=============2

to this

1====\     /====2
=           =
2====/     \====1

 

 

effectively creating an X pattern and putting the load in both directions

place the clamp in the center of the X pattern and it will pick up the full load on both wires

if it reads negative, just reverse it

this has worked for me

• This reply was modified 2 years, 7 months ago by charettepa.
• This reply was modified 2 years, 7 months ago by Kevin @ Emporia.
• This reply was modified 2 years, 7 months ago by Kevin @ Emporia.
• This reply was modified 2 years, 7 months ago by Kevin @ Emporia.
• This reply was modified 2 years, 7 months ago by Kevin @ Emporia.

[djwakelee]

Yes, you can add the currents of the 120V or 240V circuits on different phases using the above method (route the other phase backwards through the same CT), but this does not yield a totally accurate power result.  To calculate power, Emporia (or any energy monitor) needs the current of the circuit (from the CT) and the voltage (from the 120/240V input).  It also figures out the phase shift between the current and voltage, which is necessary to calculate real power (W) and not apparent power (VA).  When you mix the two phases in the same CT, the voltage source of only one phase is referenced.  If your 120V legs are not split exactly (one high and one low), that will yield an error in the power calculated.

Also, if you do this with 240V circuits, there is additional error since Emporia currently doesn’t deal well with 240V single clamps – we need to use the kludge multiplier.  And when you do that, the software just multiplies the one phase by 2x, instead of adding the voltage of both phases.  But that is a limitation with single clamp 240V for all circuits right now – not just if you try and combine them.

• This reply was modified 2 years, 7 months ago by djwakelee.

[charettepa]

Before switching to double clamp I compared the values. I used 3 clamps total 2 separate and one with both wires. I ran this way for 3 days. All numbers added up. The 2 separate values address exactly to the combined one.

[djwakelee]

Probably hard to measure precisely as there is enough variation clamp to clamp – Emporia only guarantees 2% (clamps and sensing).  If your 120V phases are the same voltages, yes – you will not see much error.  But nonetheless, there will be some if your phases aren’t balanced – even if small.  This will also depend on what loads you have, with resistive (like a hot water heater element) being less affected than older non-power factor corrected electronics, and inductive or capacitive loads.

[charettepa]

in my case I combined in 2 cases

 

1- the AC which is balanced

 

2- the Dryer which is not balanced

the dryer always had 300w more on one of the clamps

which i’m certain is the motor turning the drum at 120v

while the heater is 240v

the 1 clamp that has both loads of the 24ov circuit for the dryer

it measured an equal amount to the other 2 added up on each separately until a few days ago when I removed the individual ones

example p1 was 2800w p2 was 2500w and the combined one was 5300w

when the heater would periodically stop and only the motor was going the single one and p1 both would register 300w with p2 at 0w

then heater would come on again and it would return to p1 was 2800w p2 was 2500w and the combined one was 5300w

as a whole, yes it may be off by a few % but thats the same individually

this should be far more accurate than picking one and multiplying by 2 as its measuring both of them

 

 

[djwakelee]

In the setup you describe, you are measuring the combined current for each wire as accurate as possible.  But the voltage being used (for the power calculation) is actually just one of the 120V phases and not the correct 240V total.  Emporia doesn’t natively support 240V measurement – it doesn’t know you have a 240V circuit.  Likely only a small error if the 120V phases are similar in actual voltage, and the resistive load of the dryer heating elements makes phase angle (critical for power measurement) not come into play here.  In doing it this way, I believe if you switch to Amps view it will also show up as double the actual amount.

[charettepa]

I am running the emporia V2

It actually supports up to 3 phases

I am running both legs of the 240v dryer circuit in one clamp. I am not using a multiplier.

It’s not just double.

I started out with 3 clamps for the dryer.  One on each leg plus one over both in opposite directions.  I ran it this way for several days. The 2 separate clamps always added up to the single one despite the 2 separate ones having 300w difference.

 

I have spoken to emporia support.

They confirmed that this setup is correct as long as the wires are long enough to achieve it and the clamp is large enough for both wires

 

 

 

 

 

• This reply was modified 2 years, 7 months ago by charettepa.

[waterpro]

I contacted customer support about this and they responded that they’re “hoping” to have the ability to lump two circuits together by the end of this year (2022).  Not sure if this is just a canned response.  Judging by when this thread was first started it’s been a feature that’s been “coming” for quite some time. now. lol.

 

 

[devdevil85]

Have there been any updates on this?

[burke031]

Any updates on when combining 2 circuits together will be happening.   Running 2 separate clamps on my dryer is a pain.   But need to since it’s not a balanced load.

[charettepa]

Follow my diagram above and you can use one set of clamps on your unbalanced 240 dryer. I have been running this way for about a year now.

• This reply was modified 1 year, 4 months ago by charettepa.

[burke031]

Does it matter which wire goes in the opposite direction?   Have to go see if I have enough wire.

[charettepa]

It does

If the value is negative, just turn the clamp around

 

 

[Trist]

It seems to me the RoCoil CT wrapped around both would be easier to combine L1 and L2 then dealing with split core?

[mfifield01]

Thanks for the suggestion of crossing the wires. I just did this for my dryer and everything seems to be reading correctly (~5.8kW).

[deac99]

In case this is monitored by Emporia support – I too would like to have this feature as I have these units in Europe monitoring multiple 3-phase circuits.  It’s a real pain that I cannot have the app sum the multiple phases.

[frjoga]

The easiest way to combine the usage from a 2 pole breaker is to put both wires under the sensor. It will give you accurate readings of the total usage rather then adding the usage of two seperate sensors or just dubling the usage of one part of the circuit.

[djwakelee]

The ability to monitor both wires on a 240V 2 pole breaker will depend on the panel wiring and current.  Because out of phase by 180 degrees, for the signals to add correctly in the CT, you need feed one wire the opposite direction.  If you are dealing with thicker and larger wires for the 240V load, this may not be possible.  And even so, this only works for summing the two hots for balanced 240V loads – those that don’t use a neutral.  You’ll also overload the 50A CT if your 240V circuit draws more than 25A, since you are doubling that in the CT with the two lines.  And, it really isn’t using the correct voltage reading from the mains, so any different in voltage from phase to phase will give some error.

Because of these limitations, unless you have small wires and a small 240V load, doubling in the app or using two CT’s is generally preferred.  Wish they would just give us the ability in the app to combine the two phases (1 CT each) into one circuit, or more cleanly deal with single CT’s for balanced 240V circuits (just flag it that way so that app knows to use the sum of the two 120V phases for the voltage, and not need to ‘double’).

Conversely, it is very easy to combine more than one 15A / 20A wire within the same 50A CT.  Provided they are on the same hot leg (same phase), or you need to also feed the wire backward.  Those 12 or 14 AWG wires are flexible and relatively small.

[att]

Hello! Just got my emporia and so far really liking it. Any news on ability to combine two circuits?

[mfifield01]

I’ve been using the method from charrettepa above for 8 months. It seems to work great. You combine both circuits into one clamp, just loop one wire so it runs backwards through clamp.

[att]

Unfortunately in my case the wires are too thick and I don’t think there’s enough slack to loop one of the wires backwards.

Would be great if there was some official word! Even if it’s a while away.

[emporiacs]

Unfortunately, right now, the Emporia app does not offer a way of adding circuits together. It’s a very common feature requested by our customers, and we’re working on that to be launched in a future firmware update, but we still don’t have an ETA for that functionality.

More information: https://help.emporiaenergy.com/hc/en-us/articles/9556368100631-Combining-measurements-

[Scooter133]

This can be for a 240 Double Pole, or two Singles on different Phases that you want to monitor as one.

[Author]

Posts