Heat pump Water Heater with no Neutral wire

[Ruff]

We decided that the Richmond 10E65-HP5U15 65 gallon water heater would meet our off grid needs. It is a 240 volt 15 map heat pump water heater.

I ran a 10/3 romex to the box where the heater will sit. Once I got the heater box open I find that there are only 2 wires that are free for connection. There is a grounding lug, but no place for the neutral wire. This is a new construction metal building with interior wood framing, normal residential plumbing and electrical (for now).

My circuit breaker panel is N-G bonded and now I am not sure what to do. Should I attach the neutral to the ground lug at the water heater, or just let it float?


Background information.
Currently the electrical service has a meter and main disconnect at a utility pole 200 feet from the house. We buried conduit with three wires of 4/0 in size from there to a three pole manual transfer switch. The power then goes to a 200 amp circuit breaker panel with a 200 amp main cut off. I ran a seperate 4 AWG wire from the ground lug of the panel to the buried ground rods next to the house. I also screwed in the small green lug in the panel. I consider this to be the N-G bonding point. All GFCI outlets seem to test and reset fine.

Jeff

 

[MakeMePower]

why would you connect the neutral at all. connect l1 and l2, and the ground.

 

[zanydroid]

We decided that the Richmond 10E65-HP5U15 65 gallon water heater would meet our off grid needs. It is a 240 volt 15 map heat pump water heater.

I ran a 10/3 romex to the box where the heater will sit.

My circuit breaker panel is N-G bonded and now I am not sure what to do. Should I attach the neutral to the ground lug at the water heater, or just let it float?

This post is kind of weird because you seem to overall have pretty good command of the project, but you were pondering whether to introduce an illegal N-G bond in this box.

You wirenut the neutral to insulate it and keep it out of the way. This prevents unwanted current on the EGCs (which I think can happen even though this appliance is 240V only) and avoids lost neutral shock risk.

 

[ricardocello]

You only needed to run 10/2 w/ground to that appliance, as it does not use any 120v power.
Had you run the 10/2, you would have needed to put black or red tape on the white wire to indicate it is hot, not neutral (for future readers).

Since you ran the 10/3 w/ground, use the black and red and ground, and as Zany said, put a wire nut on the white neutral wire unconnected to anything.
Someday you might need to use it.

 

[Ruff]

This post is kind of weird because you seem to overall have pretty good command of the project, but you were pondering whether to introduce an illegal N-G bond in this box.

You wirenut the neutral to insulate it and keep it out of the way. This prevents unwanted current on the EGCs (which I think can happen even though this appliance is 240V only) and avoids lost neutral shock risk.

I cannot agree more about this post being weird. It seemed to make sense when I wrote it.

I have been putting up plywood backer board and doing carpentry work most of the day and then shifted to the water heater. I could blame it on me being tired, but instead, I will just blame it on my age

Thank you to everyone who responded. It is good to know that even the dumbest questions by can get help for this forum.

 

[Ruff]

You only needed to run 10/2 w/ground to that appliance, as it does not use any 120v power.
Had you run the 10/2, you would have needed to put black or red tape on the white wire to indicate it is hot, not neutral (for future readers).

Since you ran the 10/3 w/ground, use the black and red and ground, and as Zany said, put a wire nut on the white neutral wire unconnected to anything.
Someday you might need to use it.

We ran 10/3 as the original plan was a conventual water heater. this new fangled heat pump thing was a last minute change.

 

[MakeMePower]

We ran 10/3 as the original plan was a conventual water heater. this new fangled heat pump thing was a last minute change.

conventional still only uses 3 wires.

 

[LithiumSolar]

We ran 10/3 as the original plan was a conventual water heater. this new fangled heat pump thing was a last minute change.

I've never heard of a water heater that needs 10/3. Everything I've ever used or worked on has been 10/2 for 240V and that's about a dozen or so electric water heaters and one hybrid heat pump water heater. Copper is expensive these days, don't see any reason to run 10/3 when it's not needed.

 

[ricardocello]

It's done, save it for potential future uses. You never know!

 

[Rednecktek]

I've seen "smart" heaters that need the neutral wire to provide 120v control voltage. I wouldn't be suprised if there were heat pump water heaters out there that needed that control voltage leg as well.

Better to have an extra wire than be 1 short!