Thanks for the replies.
1) The heater will require a 30 amp double pole circuit breaker. Swap out the existing 40 amp breaker and replace with a 30 amp double pole.
2) At the 30 amp breaker, terminate the branch circuit red and black conductors to the 2 screws on the 30 amp breaker........ie......1 hot for each leg.
3) At the electrical panel, disconnect the white neutral branch circuit conductor from the neutral bus bar as it will not be needed. Place a plastic wire nut on the unused white neutral.
4) The bare copper ground from the branch circuit will land on either the panel main neutral bus bar or onto a separate equipment ground bar.
5) Connect the heater black to the branch circuit black. Connect the heater white to the branch circuit red. Place some black electrical tape on the heater white to re-identify it as a hot conductor.
Connect the heater green ground to the branch circuit bare copper ground.
The white neutral from the branch circuit will not be used. Place a plastic wire nut on the white neutral. The 8 AWG copper conductors are OK, therefore re-use these conductors.
6) If the heater does not contain a unit disconnect switch, you will require a 30 amp double pole ON/OFF switch at the heater area.
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