Which type of voltage can be used without caution in regards to conductor separation rules?

Using under 12 VDC is considered safe and does not typically require stringent adherence to conductor separation rules. At this voltage level, the risk of electric shock or fire is significantly reduced, allowing for more flexible installation practices, such as bundling wires together without the need for complicated routing that is often necessary with higher voltage systems.

In contrast, higher voltage options, whether they are AC or DC, introduce significant risks and require careful consideration of separation distances between conductors. This is to prevent hazards like electrocution or equipment failure due to unintended conduction paths. Therefore, under 12 VDC stands out as the safest choice when it comes to minimizing precautions regarding conductor separation.