1 or 2 dedicated 120VAC circuits for my CNC?

Use MTW for current carrying applications.

MTW Wire - UL 1015

A type of hookup wire with a highly stranded bare copper conductor typically used in control cabinets, machine tool applications, and appliance wiring applications such as HVAC equipment. Wire & Cable Applications for MTW Wires are best for use in dry locations at 90°C, or not to exceed 60°C in wet locations or where exposed to oils or coolants.

The Beldon cable is best for signal applications. It is a bit of overkill for most switch inputs.

So addressing your questions:
1. Because each individual conductor should stay below the individual conductor max temp of 105c when the cable is operated at xxx amps at yyy temp.  To see if this is the case, look up other cables in the same Belden family and compare the 2-conductor to a 12 (or more) conductor of the same AWG.  I bet the high-conductor count cable has a lower amp-per-conductor rating than the 2-wire.

2. Because they're different cables, meeting different specifications and intended for different use-cases.

3. I would treat  the number given is their max rating, but you should contact Belden for clarification.

Thanks for your speculations. That kinda makes sense. 

scotth wrote:

Use MTW for current carrying applications.

MTW Wire - UL 1015

A type of hookup wire with a highly stranded bare copper conductor typically used in control cabinets, machine tool applications, and appliance wiring applications such as HVAC equipment. Wire & Cable Applications for MTW Wires are best for use in dry locations at 90°C, or not to exceed 60°C in wet locations or where exposed to oils or coolants.

The Beldon cable is best for signal applications. It is a bit of overkill for most switch inputs.

Thanks. I was not aware of this classification. I will look into it.

Yeah I am still trying to determine sizing for the different circuits. Wire gets expensive these days especially when you have so many different sizes and ratings.

MTW is a lot cheaper than Beldon. Beldon is a wonderful product and works well for intended applications.

Quick question:
Can I hardwire the 30A line to my cabinet and just have it plug into the wall with a 30A plug/outlet? Or should I have the cord plug into the cabinet via a inlet/outlet as well? I was just planning to go the hard wire route to save money and one less connection to deal with.

Sorry if this is a dumb question. Just checking in case there is a specific reason not to hard wire that I may not have thought of.

Thanks

Hardwire to the disconnect switch inside your cabinet (use a cable gland through the housing panel) and a plug on the other end.

Less to go wrong.