Originally Posted by 5picker
Most units today have a separate feed from the breaker box.
While you might piggyback onto another circuit I would caution that route.
Water heaters can draw 8-12 amps so a dedicated circuit is best.
X2. The SW6DE usually comes with a 1440 watt heating element stock. That translates to 12 amps. So you need a dedicated 15 amp circuit to power up the water heater element.
If there is not a dedicated circuit already in place (you may luck out and there is one), accessable behind the water heater, you may have to run one directly to the electrical distribution panel for this, as you can see in the pics below this dedicated circuit. Look at your panel to see if you already have a circuit breaker for this.