Does anyone have a comment on my question post number 12 about the difference between those two meter sockets, the 114 TB (with 5th jaw accessory added) and the 115 TB? The 115 is a factory five jaw and it says it's for three phase three wire. Now I get they will be using the two watt-hour method for that and they need the fifth terminal to get voltage from the third phase, but this seems mechanically equivalent to the metering of 120/208 single phase where you need a voltage reference on that grounded conductor. So in either case you have that conductor splicing in the meter socket with a pigtail up to the 5th jaw......So why do they spec two different meter sockets for the two?