Meter attached to my EVSE

[ABCCBA]

Rick,

Based on the image you provided, you appear to have a PZEM-004 AC 80-260V 0-100A Meter Module Multifunction Energy Metering AC Power Monitor. I searched a few sites that sell this meter and have found that it is can accept up to 260VAC input. The following link provides the technical information as well as a wiring diagram. https://www.circuitspecialists.com/content/189799/ac004.pdf

Power = Watts = Volts * Amps

So, to meter your load properly, you need to supply the meter with the proper voltage and current. Thus, since you are metering a 240VAC, single phase application, you must provide 240VAC input to the meter.

How to get the 240VAC? First, there is minimal current draw from the meter itself, so I would say that you can use 18 awg or larger with no problem. Make sure the wire is rated for greater than 250VAC.

As to where to tap the voltage from, you need to find a way to tie the two voltage sensing wires to the actual L1 and L2 wires that are serving your charger.

As to if the meter needs to be on its own breaker, I would say no, as long as L1 and L2 that you would be connecting to are protected by a breaker.

For safety, I would install an in-line 2 amp fuse on one of the voltage sensing wires where it connects to the meter. This would allow the fuse to protect the meter, just in case something happened.

The following is provided for illustration purposes. Check and follow local codes and consult a licensed electrician

How to tap you voltage sensing wires: 1. Turn the breaker OFF and double check with a voltmeter that there is no voltage present. 2. Find a screw terminal were the L1 and L2 conductors are landed. 3. Loosen the terminals and remove the conductors. 4. Strip approximately 1 1/2" of the voltage sensing wire ends. 4. Twist one wire on L1 and the other wire on L2. 5. Place the conductors back under their respective terminals and hand tighten. 6. Gently pull each wire to ensure that it is secured under the terminal. 7. Connect an in-line fuse module to L1 input on the meter. 8. Connect the the L1 voltage sensing wire to the opposite side of the in-line fuse fuse. 9. Connect L2 voltage sensing wire to the L2 input of the meter. 10. Verify all wiring connections are tight and then turn the breaker on. 11. Verify that the meter energizes. 12. Connect a load to the circuit and verify that the meter is measuring and displaying all values.

Hope this help point you in the right direction.

PLEASE! Do Not attempt this if you are uncomfortable.

Mike, I guess that would make sense. Thanks.

I am not sure how to safely provide 240 V to the meter. Currently, I have a 120 outlet just below the meter with 18 gauge lamp cord plugged into the 120 V receptacle providing power. (I also have a 30 dryer receptacle next to it). Do I bring the L1 and L2 voltage conductors to the ammeter from the panel or the 30 amp receptacle? In either case, what wire gauge is used since the meter draws such little amperage on its own and would it need its own circuit and circuit breaker?

View attachment 182903

 

[SDRick]

Mike and Brantse,

I appreciate your response and approach to wiring the meter for 240 V. My concern is not with the theoretical or physical wiring itself, but potentially running afoul with the electric codes.

My concerns are twofold.

Can two conductors share one breaker or receptacle terminal?
I was under the impression that the breaker size controls the gauge of the corresponding wire for the circuit and when is it allowed to use a downstream fuse to protect the device?

 

[brantse]

Can two conductors share one breaker or receptacle terminal?

I'm not an electrician or EE, so I apologize if I say something incorrectly or misinterpret your question. I think you're referring to two wires physically landing on a breaker....in that case, yes, I think that is specifically not allowed. My install picks up the voltage at terminals in my 14-50 enclosure/receptacle, which I don't believe would have such restriction. It's no different than connecting outlets or lights in series.

 

[SDRick]

I'm not an electrician or EE, so I apologize if I say something incorrectly or misinterpret your question. I think you're referring to two wires physically landing on a breaker....in that case, yes, I think that is specifically not allowed. My install picks up the voltage at terminals in my 14-50 enclosure/receptacle, which I don't believe would have such restriction. It's no different than connecting outlets or lights in series.

I am having an electrician install a few more solar panels next week so I can ask him as well as the inspector when he comes by.

Electric codes can be tricky but I thought remembering something that if a circuit breaker is designed for more than one conductor per terminal it would be allowed (I doubt many are). Similarly, if the receptacle is allowed for more than one conductor the same thing would apply. I'm not sure if most 30 and 50 amp receptacles are designed for multiple conductors on one terminal. Especially a 6 gauge and an18 gauge wire going to the same terminal.

As I said before, the wiring is pretty straightforward, the codes not so much.

 

[brantse]

Similarly, if the receptacle is allowed for more than one conductor the same thing would apply. I'm not sure if most 30 and 50 amp receptacles are designed for multiple conductors on one terminal. Especially a 6 gauge and an18 gauge wire going to the same terminal.

As I said before, the wiring is pretty straightforward, the codes not so much.

That's certainly a valid point. I really don't know whether these receptacles "technically" allow multiple conductors, or not. You could avoid having to do that entirely by splicing in upstream of the receptacle (provided that was done appropriately).

 

[ABCCBA]

Rick,

NEC and therefore local codes will call for landing the conductors on separate terminals, unless the terminals are marked/labeled for use with multiple conductors. If you are going to install the meter per code by installing a new panel breaker, then you will need to install as small of amperage dual pole breaker as you possibly can find, for your meter. Additionally, I would still install an in-line fuse because you will not find a dual pole breaker with small enough amperage to trip if the meter fails.

Oh, and if you do use a separate breaker, then make sure you look at the manufacturer's specs for the minimum conductor size for the breaker terminals, too.

Mike and Brantse,

I appreciate your response and approach to wiring the meter for 240 V. My concern is not with the theoretical or physical wiring itself, but potentially running afoul with the electric codes.

My concerns are twofold.

Can two conductors share one breaker or receptacle terminal?
I was under the impression that the breaker size controls the gauge of the corresponding wire for the circuit and when is it allowed to use a downstream fuse to protect the device?

 

[SDRick]

Rick,

NEC and therefore local codes will call for landing the conductors on separate terminals, unless the terminals are marked/labeled for use with multiple conductors. If you are going to install the meter per code by installing a new panel breaker, then you will need to install as small of amperage dual pole breaker as you possibly can find, for your meter. Additionally, I would still install an in-line fuse because you will not find a dual pole breaker with small enough amperage to trip if the meter fails.

Oh, and if you do use a separate breaker, then make sure you look at the manufacturer's specs for the minimum conductor size for the breaker terminals, too.

Yes, good points. Something so comparatively simple may not be. As I mentioned earlier, my current setup is the meter plugged into a typical 120 V wall receptacle. I would assume this would be to code just like plugging in a clock radio.

Similarly, what if I plugged in the meter into my unused 30 amp dryer receptacle? The only question then may be am I required to use 10 gauge wire or cannot get by with something less?

In any event, the 2 amp inline fuse to protect the meter is a good idea.

 

[ABCCBA]

Plugging into the 240VAC outlet is not an issue, but still use the in-line fuse.

I did not read the specs to see if the meter is polarity sensitive. If it is, and when you plug up the meter and it shows negative current flow and negative wattage, reverse the L1 and L2 voltage input wires.

Yes, good points. Something so comparatively simple may not be. As I mentioned earlier, my current setup is the meter plugged into a typical 120 V wall receptacle. I would assume this would be to code just like plugging in a clock radio.

Similarly, what if I plugged in the meter into my unused 30 amp dryer receptacle? The only question then may be am I required to use 10 gauge wire or cannot get by with something less?

In any event, the 2 amp inline fuse to protect the meter is a good idea.

 

[davewill]

Personally, I would wire the voltage sensing wires as close to input to the actual EVSE as possible. If you're getting voltage sag on the circuit feeding the EVSE, you won't see it on the meter if you're connected to a different circuit. I would tap the voltage wires in alongside where you're putting the current transformer, as close to the EVSE end of the circuit as possible. That's why people have been doing them inline on the cable for the EVSE.

I have one in my OpenEVSE (I didn't build it because I can't do work that neat). In that case there was room in the EVSE's enclosure and it's integrated into it. You can see the fuses that are protecting both the meter and the power supply for the electronics.

 

[gkalexdc]

Thanks Electricfan. Here's the completed project.

 

[Electricfan]

View attachment 184573 View attachment 184574 View attachment 184575 View attachment 184576 View attachment 184577 View attachment 184572 View attachment 184571 Thanks Electricfan. Here's the completed project.

Nice job! That looks great.