it is a low power preamp ADC.
I thought to keep the toroidals in an external box for lower noise and as there is not much room in the main box. ( i also may experiment with an external battery box later)
That explanation raises as many questions as it answers. What kind of "noise" are you trying to reduce? Acoustical buzz from the transformer itself? Low power transformers, and especially toroidal transformers should not have any acoustic hum or buzz.
Magnetic noise? Are you using unshielded audio transformers (such as a microphone preamp, etc.) Toroidal transformers are noted for their minimal external magnetic field.
Even the world's most respected audio test equipment where you would expect the utmost isolation from mains power noise (for example Audio Precision) uses internal mains-connected power supply circuitry. Using external transformers seems like shades of audiophoolery. It is easy enough to isolate even sensitive circuitry from internal linear (or switch-mode) power supply circuits.
Furthermore, designing external mains-frequency AC power input seems incompatible with the option of using optional battery power. Perhaps you should consider how you intend to generate all the necessary voltages in battery mode before committing yourself to this scheme.
I am considering a scheme where I have an internal SMPS to generate all the voltages (+5V, +/-15V, +48V) from a 12~24V DC input. That allows international users to use the DC wall-wart (or line-lump) power supply of their choice. For example re-cycling a disused laptop power brick, etc.
To answer your original question, no, multiple-core AC wiring does NOT require any kind of shielding or special handling down at mains frequencies.