CTs work on the physics of induction -- of unsteady electro-magnetic currents -- in this case alternating current.
In every CT cabinet I've had the pleasure to know, the conductors are engineered so that they pass straight through the cores of the CTs -- with no sharp bends in sight.
When a CT is cutting the EM fields of two (2) conductor elements -- at right angles to each other it's suffering a phase shift directly from said geometry.
In the case at hand, the CT is deep into the field of the neutral -- visibly touching it. It's also shockingly close to its ninety-degree face.
These two (2) induced currents -- on the same wire -- HAVE to be out of phase due to the geometry.
Inducing currents that must be out of phase should toast like a feeble bolted-short: battling waves, if you will.
This phase shift can be eliminated by shielding the CT with a trivially cheap sheet of conductor: aluminum would be perfect.
In a corner grounded scheme, the current passing through the neutral bus would not be trivial. Even though it's earthed, it's still pumping as much energy as the other legs in what I assume is a three-phase system.
EUSERC hates such tricky schemes, so my experiences do not reflect those of the eastern states.
{It's EUSERC's position that clever schemes generate danger to firemen and Poco talent when the stress is on. It's better for all concerned if the Service options are highly constrained so that when an emergency strikes everyone is looking at the same familiar scheme.
California led the way on this front because of earthquakes and the rapid expansion during WWII. Bringing talent in from all over the country -- in a grand style and in a total rush -- caused wartime installations to become confusingly 'tricky.' The Poco's started suffering fatalities as their new hires didn't recognize oddities -- starting with corner-grounded schemes.}
