ECN Forum Forums Code Related Discussion Canadian Electrical Code Topics 600V single phase 2-wire

If you are running a 50mm DB2 underground conduit, for a 2-wire, single phase 600V system (no neutral) between two lighting panels (which have a 600V to 120V transformer) is it mandatory to run a third wire as bonding conductor(to ground)?

The panel themselves have their own grounding electrodes.
The 600V circuits are #2Cu, so in general the code would call for a #6 bonding conductor.

What is the CEC rule/subrule that would make the bonding conductor mandatory? I am not sure I read 10-106 properly.

You do have to install a bonding wire with the 600 volt wires so if a fault occurs on the primary side that the upstream breaker can trip. The secondary side has a new ground and bonding jumper to serve the 120 volt side.
There are some cases where you can save on the bonding wire but not this case.
When you feed an out building and create a new service entry the neutral can act as the bonding and as the grounded circuit conductor but because the 2 systems are electrically isolated the 600 volt side needs a bonding wire to return fault current to its source but not for the secondary which works like a new service.