Can I Put the Neutral Wire on the Ground Screw of a Water Heater?
A user asked the app whether the neutral wire can land on the ground screw of a water heater. The answer is no, and the question usually means one of two situations is happening at that water heater. Either a white wire is being mistaken for a neutral, or someone is missing a conductor and hoping the ground can do double duty. Both deserve a clear explanation.
Why the Code prohibits it
NEC 2023 250.142(B) prohibits using the grounded conductor for grounding equipment on the load side of the service. The reverse is equally prohibited: the equipment grounding conductor cannot serve as a neutral. The ground exists to carry fault current only, so a breaker trips fast during a fault. The moment it carries normal return current, every bonded metal surface in the path, including the water heater jacket and the piping connected to it, becomes energized at some voltage above ground. If that borrowed path ever opens, the full line to neutral voltage appears on the tank. The old exception that allowed frames of ranges and dryers to be grounded through the neutral died in 1996 and never applied to water heaters at all.
Most water heaters have no neutral
A standard residential electric water heater is a straight 240 volt load: two hots and an equipment ground, commonly run as 10/2 NM where the white conductor is used as the second hot. Per 200.7(C), that white wire must be reidentified with tape or marking at every visible point, which is the step that prevents exactly this confusion. There is no neutral because a 240 volt element needs no return to the grounded conductor; both legs alternate against each other. So if you are looking at a white wire in a water heater junction box, odds are it is a hot that someone failed to re-mark. Put a wrap of black or red tape on it, land it on the second line terminal, and land only the bare or green wire on the green ground screw.
If a real neutral situation exists
Some heat pump water heaters and units with 120 volt controls do use a neutral, and those come with a 4 wire circuit or manufacturer instructions saying so. In that case the neutral lands on the designated neutral terminal per the instructions, never the ground screw, and 110.3(B) makes the instructions enforceable. If the circuit genuinely lacks the conductor the appliance needs, the fix is pulling the correct cable, not improvising with the grounding system.