routercnc_MK3

[JAZZCNC]

Questions on the contactor:
T1, T2 are the mains input ?
L1, L2 are the switched output ?

Yes Either or doesn't matter really it's just a switch.

Should I keep the earth permanently connected (i.e. not through T3/L3 of contactor) ?

Yes leave Earth unbroken.

A1 / A2 24V DC polarity important? I'm guessing not.

Yes it matters. A1 is Positive A2 Negative.

There is a 0 / 1 switch in the middle - some sort of tester / over-ride? Can I leave it at 0 ?

It's not a switch it's a Lever. The Contactor can have a Module added onto front and this switches it. Look inside the Box it came in and you'll see what i mean.?