Current Transformer or CT wires

[jaggedben]

Note that the red on the 50A below the main doesn't match the phase of the red on the 15A above two spaces above the main. Those sorts of things need to be sorted out when doing this.

(Also note that Siemens, in their infinite wisdom, has done their factory reds 'wrong' in my opinion. While not code required, the convention is for black to go on top. Sometimes the existing wiring on a panel like this matches their colors and sometimes they are all the other way, and frequently it's a mess. You decide which way to fix it, but consistency matters when doing CTs this way.)

 

[SKSolar]

Note that the red on the 50A below the main doesn't match the phase of the red on the 15A above two spaces above the main. Those sorts of things need to be sorted out when doing this.

(Also note that Siemens, in their infinite wisdom, has done their factory reds 'wrong' in my opinion. While not code required, the convention is for black to go on top. Sometimes the existing wiring on a panel like this matches their colors and sometimes they are all the other way, and frequently it's a mess. You decide which way to fix it, but consistency matters when doing CTs this way.)

Thanks for noting those. I will use a current tester to sort them out.

 

[Harris]

The doc cited above still calls it 'recommended'. Previous instructions didn't mention twisted pair at all.

 

[Solar_ice_caps]

Thanks for sharing.
The costs of those CT wires are beyond imagination consider the size of them. In the end I bought the Southwire 600V #18 AWG wires @$18 per 100 feet (4 x100 wires) and twisted them together. So I have two pairs and I haven't installed them yet . Mt extension is about 80 feet from Combiner to the MSP. My MSP main breaker has 2 poles and therefore, I have 2L1 and 2L2 need to be hooked up with 4 CTs but the combiner only came with 2 Consumption CTs.
These extended twisted pairs are to be connected in the Combiner box and 2 pairs of L1 CT wires & 2 pairs of L2 wires connect to the other end of the extension CT wires in parallel in the MSP.
I hope that works. These are my twisted wires.
View attachment 2569050

At this point with everything I've read I am pretty confident your solution will work at the length you've listed. At longer length the wire size needs to increase to keep resistance low.

I had some other installers in another forum saying they use landscape wire and thermostat wire and it works fine. I had bought some 18/5 thermostat wire, but it is rated Class 2 and the Enphase CT documentation has specific warnings against using Class 2 wiring and equipment.

Did you get your #18 600V wire locally or did you have to order it?

 

[SKSolar]

At this point with everything I've read I am pretty confident your solution will work at the length you've listed. At longer length the wire size needs to increase to keep resistance low.

I had some other installers in another forum saying they use landscape wire and thermostat wire and it works fine. I had bought some 18/5 thermostat wire, but it is rated Class 2 and the Enphase CT documentation has specific warnings against using Class 2 wiring and equipment.

Did you get your #18 600V wire locally or did you have to order it?

I ordered them from ebay. I made sure that the wires I bought have 18 awg and 600V on it.

 

[SKSolar]

Note that the red on the 50A below the main doesn't match the phase of the red on the 15A above two spaces above the main. Those sorts of things need to be sorted out when doing this.

(Also note that Siemens, in their infinite wisdom, has done their factory reds 'wrong' in my opinion. While not code required, the convention is for black to go on top. Sometimes the existing wiring on a panel like this matches their colors and sometimes they are all the other way, and frequently it's a mess. You decide which way to fix it, but consistency matters when doing CTs this way.)

jaggedben, I believe you may have worked on CTs on the Murray MSP before like the one I have. Were you able to use 2CTs instead of 4 CTs to clamp all the wires from the load breakers? I am using the circular CT clamps. Just wonder to buy another 2 or not.

 

[Solar_ice_caps]

jaggedben, I believe you may have worked on CTs on the Murray MSP before like the one I have. Were you able to use 2CTs instead of 4 CTs to clamp all the wires from the load breakers? I am using the circular CT clamps. Just wonder to buy another 2 or not.

Not who you asked, but generally you can add additional CTs and splice or terminate them in parellel, so long as they are on the same phase, and they will be additive.

For Enphase specifically this is true and you can find it in their docs.

So for example for a white/blue cable you can have a CT on each L1 and terminate both white leads into the same terminal and both blue leads into the same terminal and the readings will be additive. Do the same for L2.

As mentioned though, you have to be careful about phasing.

 

[jaggedben]

I've probably used 2 sets of parallel CTs in most of the cases where I had to capture all the individual circuits. Not all, but most of them. You may have to search for it but somewhere in Enphase's documentation is info about how many wires fit in a CT.

 

[SKSolar]

jaggedben,

Merry Christmas!

I am wiring up my 3rd GEN Enphase ESS – Solar plus Battery with no backup. This is prior to AHJ wiring inspection at this point.
I just have 1 IQ Battery 5P and a Combiner 5C. No System Controller and Load Center. That is the selling point of Enphase in response to the low energy export rate of NEM 3.0.

As I went through the Quick Installation guide in the installation of Combiner 5C, at one point after connecting all the wires, it calls for “Energizing the Combiner- by turning all the circuit feeding the IQ Combiner".

Question:
Where does the power come from when I am not connected to the Grid (with no Utility PTO)? And also my understanding is that the microinverters is not sending power from PVs when it is not tie to the grid. How can I energize the Combiner at that point?

Since the Utility’s PTO comes after the AHJ wiring inspection, what are the stuffs that the AHJ inspector would like to see? Is the inspector looking to see all the Equipment being hooked up before he sign off? What is your advice on preparing for AHJ inspection?

Is an Enphase installer require to be present when the Utility Inspection came prior to issuing the PTO? Does the installer require to turn on the system to the Utility Inspector to make sure the system is working as proposed? Sharing your expertise experience is very much appreciated.

Thanks

 

[Carultch]

Question:
Where does the power come from when I am not connected to the Grid (with no Utility PTO)? And also my understanding is that the microinverters is not sending power from PVs when it is not tie to the grid. How can I energize the Combiner at that point?

Since the Utility’s PTO comes after the AHJ wiring inspection, what are the stuffs that the AHJ inspector would like to see? Is the inspector looking to see all the Equipment being hooked up before he sign off? What is your advice on preparing for AHJ inspection?

Is an Enphase installer require to be present when the Utility Inspection came prior to issuing the PTO? Does the installer require to turn on the system to the Utility Inspector to make sure the system is working as proposed? Sharing your expertise experience is very much appreciated.

Standard grid-tied solar cannot be operated until there is a grid-forming source to establish the AC voltage, frequency, and waveform. While waiting for utility power, it remains off, and the panels will remain at open circuit voltage, with all sunlight turning into heat. If you want to test it in advance of utility power, you need to supply your own grid-forming source. Such as a battery inverter system, or a generator/load bank system. Many utilities allow you to temporarily test your system in advance of PTO (but with a standard utility service), and just not keep it on long term.

An AHJ wants to see that your system is built to code. Not every AHJ has the same things they look for, so I can't speak for every jurisdiction. Some may want to see your work in advance of modules, or other major milestones such as inspecting trenches in advance of backfill, so if there is an issue that otherwise would be labor-intensive to correct, they can tell you about it. Even if they don't want progress inspections, take a photo record of anything that would be labor-intensive to take apart while still under construction, so you can show that it was done properly.

It's uncommon that they want to see it operate, but in the event that they do and it is a catch-22 to follow through with it, I would expect a pre-energization inspection, and an inspection after you have power at the site.