UTC A-10 - no electrostatic shield?

I assumed the ground lug on the A-10 was the Faraday/electrostatic shield, but John from Crimson Transformers informed me otherwise. I tested continuity between the ground lug and the case, and sure enough John is right. Another GDIY member said the UTC A series literature mentions "high electrostatic shielding" on some units included the A-20.

So why doesn't the A-10 have electrostatic shielding? Because of the humbucking design?

https://groupdiy.com/index.php?topic=35743.msg536253#msg536253

https://groupdiy.com/index.php?topic=55150.0


Looks like he's showing one, I can't say I interpret CJ correctly. 

Would a A-33 shield be helpful ?

sorry if those shied cans in the HA-100X was confusing

there are three types of shields ,  four if you count the date orchard in Indio CA

internal shield- a strip of foil or a layer of wire in between pri and sec,
this is to lower capacitance between pri and sec and thus improve HF response,

then you have your cans, the outside can for most transformers, and nested cans like the HA 100X for shielding outside demons from entering the coil/core assy,  sometimes those cans also have a layer of copper in between them for e field,  mu metal is used for most nested cans UTC uses something cheaper that they claim works almost as good but it looks more like a tin can material

then you have the "waste band" copper shield that you sometimes see on a pwr xfmr to keep stuff from radiating outward into a sensitive circuit

i do not know why the A-10 and HA 100X do not carry internal shields.
note that the internal shields must be insulated on one end to prevent a shorted turn , in the case of a wire shield one end of the single layer wind is left floating.