emonTx V4, emonVS in North America

But I think the entire emonVS and emonTx would then need to fit inside the breaker box. I don’t think that will happen to most people. Once you move the devices outside the breaker box, the outlet is a good way to go.

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Using one of these:

makes it impossible to confuse the 240 V outlet with one of these:

This might be my ignorance of the emonVS setup is showing, but isn’t there a cable running between the two? Could you not treat the emonVS as just another sensor, alongside the CTs… then wires would run from all of the sensors out to the emonTX?

@Bill.Thomson might know what the insulation requirements are for wires coming out of the panel.

Don’t you need 4 pins? I think you’ll need a Neutral for the 120V loads, and apparently it needs a safety earth as well.

Yes, it does need 4 pins, A & B legs, Neutral and Earth.

Indeed there is - and it’s 5 V maximum inside, referred to earth. The only requirement that I can possibly think of is it will need a physical barrier between it and the 120 V wiring - which should not be difficult as there’s quite a distance between the two groups.

IIRC, wires carrying the lowest voltage are required to have insulation rated the same as
that for wires carrying the highest voltage. Given that’s 240 Volts, (in this case) and the use of 300 Volt rated wire is very common in the US, that shouldn’t be an issue.

The “gotcha” is mixing LV and HV wires in the same conduit is a no-no.

Yep. Dunno what the hell I was thinkin’

That means we use one of these:


as was mentioned earlier in the thread.

There’s no marking on the flat “output” cable to indicate a voltage rating - not surprising really. I doubt it is 300 V though. @glyn.hudson should be able to tell us. I suspect it is 150 V.

I mentioned the 300 V stuff simply because it’s a very common rating for electrical
wiring used in a typical US residence.

But, as long as its rating is at least 240 V, it’d be OK for use over here.

The cable & connectors looks like this: 3m RJ12 6P6C 6 Core Straight Wired White | Cablenet - but there’s absolutely no useful information on that website.

This from RS https://uk.rs-online.com/web/p/telephone-cable/0561940 is 150 V, so I’d guess this applies to ours. The dimensions over the cover are about right, also from the look and feel of the cable.

Around these parts at least, stuff installed inside the fuse box needs to withstand higher voltages than stuff hanging off an outlet… maybe 5kV instead of 2kV (but don’t quote me on the numbers). The EmonVS has been through some safety tests, but exactly what that involved isn’t clear.

Let me summarize this idea to make sure I’m caught up.

  1. Install the emonVS-PSU inside the breaker box.
  2. Connect L1, L2 to a 2-pole breaker and the neutral bus (as @dBC posted in the video above).
  3. Connect E to the ground bar.
  4. Run the RJ12 cable out one of the knock-outs to the emonTx V4, similar to what most of us have been doing with the CT cables going to our emonTx V3 all these years.

Seems tidy. Anything I am missing?

Wouldn’t be a bad idea to line the knockout hole with a bushing to give the wire
jacket some protection from the sharp edge the knockout is going to leave.
Code says they’re required, so if you want to keep it to code…

Something like this:

or this:

Don’t forget to keep the LV and HV wires/cables separated from each other. :wink:

Other n’ that, looks good.

The bit about ensuring the EmonVS and the RJ12 cable are all rated as suitable for use in that environment (the CTs and their cables are)

If you already have a 2-pole breaker in your load center, depending on the guage of the wire
attached to it, you might be able to add the wiring for the emonVS directly to the breaker.

If the wire in the breaker is a lot larger than the emonVS wiring, you can add a short pigtail to the breaker, then use wire nuts to attach the emonVS wire to the pigtail.

(code says it’s OK to have two wires attached to one breaker)

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Regarding the emonVS-PSU in North America (both the currently-available 1-input version, and the likely future version with two inputs for split-phase voltage): my understanding is that the CM choke and filter are there to meet EMC standards. I asked about it and Glyn replied here. Earlier in the same conversation, Trystan attached the test results showing the EN standards met.

My question now is, are these components necessary in a US configuration of the emonVS-PSU?

Do they have any impact on the accuracy or function of the emonVS-PSU, or are they there exclusively to meet EMC standards? (Since there is a CM choke and filter both before and after the PSU in the current configuration, my question applies to all four compenents.)

I don’t know whose EMC standards are “tighter” (I suspect it’s the UK’s)
but the US has similar requirements.
(you’ve probably seen the mark pictured below on your electronic devices)


All components in a circuit affect circuit operation to some extent.
How much the EMC components affect circuit operation depends on how well the circuit designer did their job. In a properly designed circuit, the undesireable effects from those components
are kept to a minimal/negligible amount.

AIUI, the components you are asking about are present to meet EMC standards.

I’m seeking confirmation regarding wiring the US NEMA 5-15P cable as the UK labeling differs from what I’m used to in North America.
L1 to black (hot)
N to white (neutral)
E to green (ground or earth)

I appreciate the help. Thank you.

Welcome, Gordon, to the OEM forum.

This looks OK to me. If you have a second ZMPT101B voltage transformer fitted in your emonVs, then the second Line conductor (red) should be wired to L2 (obviously not available when using this particular connector), and you’ll then be able to monitor the voltage of both legs of your supply. You can then pair each c.t. with the appropriate voltage which will give you the most accurate power data.

Power for the emonTx4 is taken between L1 & N, any voltage in the range 100 - 255 V, 50 or 60 Hz.