Solar System requires external meter.

[RASCORP]

I'm installing a new Solar System. House has 400a service. Two 200a legs come off main meter an into a subpanel immediately next to main. The sup panel separates the 400a into two legs of 200a each. One 200a leg goes directly into another subpanel in house. to serve mostly the A/C's and 220v lines to appliances. The other subpanel (200a) feeds a few other items,, pool, hot water etc. We decided to use side taps before the 200a breaker on second leg. All works perfect per engineers diagram. We desired a realtime external meter that requires installation of CT's. The supplier of the Solar meter suggested we place 200A CT on one of the legs. Although they are suppose to be smarter than I, a simple electrician, I realize this arrangement would not provide all the power being use from the Power company. I know I need to get a measurement of entire 400a service. In all the confusion (not mine) It was suggested I order the meter, and two 400a CT's. Now for my question to you. No I don't believe I actually need two 400a CT's but they have been shipped to me, and I have paid for them. Along with the external meter of course. Will a 400a Split CT work if only a 200a would be needed?

 

[mivey]

yes. You will not be as accurate a lower current and unreliable at very low current. At 10% rated, the accuracy is cut in half. So the 200 amp CTs have 1/2 rated accuracy at 20 amps but unreliable below that. The 400 amp CTs have 1/2 rated accuracy at 40 amps but unreliable below that.

Looping the primary wire is probably not an option or you could fix the ratio by running it through the CT twice.

 

[Willh5080]

Yes, it'll work

 

[RASCORP]

No cannot wrap the large lines around the 400a coil to improve accuracy. I believe the amperage thru the coils will be well over 40a. Thank you for your input.