Sparkee... you first have to identify to us exactly what you have.
On first glance what you show us in the diagram is a single phase 120 volt three wire system, or what is commonly refered to as a "split phase" system
But then you mention "This gives us 110v between them , but generally we make one 55 leg the neutral and earth it as other wise we have a 'live' neutral of 55v all the time". This sounds to me like a three phase corner grounded delta system.
If it is in fact a three phase corner grounded delta system then yes... the three phase calculation is the correct one to apply to get the proper neutral current.
If it is not three phase and is in fact single phase then, no, the three phase caluclation should not be used to calculate the neutral current. If it is single phase the neutral current would be the unballanced draw from both sides of the system, or 2.08 amps.
Another thing... if it is single phase, there is no "phase difference" between the two 120 volt sources. What they are is two "in phase" voltage sources connected in series so that their voltages are additive. This is the only way possible for the combined voltage level across both sources to equal 240 vac (or the 110 volts from the text of your last post). Some people like to say that split phase legs are 180 degrees out of phase with each other, but that is not a proper or true description of what we have. Think DC for a minute. Take two 12 volt car batteries, to get 24 volts, you connect the batteries together so that the negative pole on one battery is connected to the positive pole on the other battery and you get 24 volts. There is no "phase difference" here. The exact thing applies on AC. It just looks like there is a difference.
And do not worry about upseting anyone, this is just another part of the learning process inherent in our trade, someone taught me, if I can spread around what I know, so much the better.
