I've got a 3ton AC condenser unit on my roof, with a blower system nearby in attic space supplied by 20A 240v circuit.
- The condenser unit is supplied by a 40A 240v circuit, 2 8ga wires
- The blower unity is supplied by a 20A 240v circuit, 2 12ga wires
- Both circuits are run through the same steel conduit from my outdoor breaker panel.
- There are no ground wires in the conduit.
- The conduit is a little corroded in places
- The total span is about 45'
- Measuring voltage in the panel, I get 118v to the ground bar on each wire and 236v wire to wire on each circuit.
- Measuring voltage on the roof (with the conduit completely disconnected from the AC unit, so only connected to the panel), I get 95v between the wire and the conduit on each of the 4 wires, but I still get 236v wire to wire on each circuit.
Why would there be so much voltage drop? It's like the conduit at the roof is at a higher potential than at the panel. Do I need to replace the whole run with new conduit, and circuits with a shared 8ga ground wire? Or run a new ground through the conduit? I can't see being able to easily do that. What size conduit do I need to carry those wires? Thanks