An electrical disconnect is a device that is used to disconnect power from an electrical circuit. It is also referred to as a disconnect switch, isolator switch, or simply a disconnect. The purpose of an electrical disconnect is to ensure that power can be safely shut off to a device or electrical system when maintenance or repairs are required. It can also be used as a safety device to prevent injury or damage in the event of an electrical fault or overload.

An electrical disconnect can take several different forms depending on the application and the level of protection required. For example, it can be a simple switch that interrupts the flow of current, or it can be a more complex device that incorporates additional safety features such as fuses or circuit breakers. An electrical disconnect is a critical component of an electrical system that provides a means of isolating power for maintenance, repairs, or safety purposes.

Yes, an electric water heater typically requires a in-sight disconnect. The National Electric Code (NEC) requires that all fixed electrical appliances, including electric water heaters, have a disconnecting means that is readily accessible to shut off power to the appliance for maintenance or repair.The disconnecting means can be a switch, circuit breaker, or other approved device that is capable of interrupting the full load current of the appliance. It must be located within sight of the appliance or located in a readily accessible location.

The in-sight part is kinda important. If the purpose of the disconnect is do de-energize the appliance so that it  can be worked on, being able to easily turn the electricity on again without seeing if the work is finished is dangerous. The commonly given explanation would be the tradesperson working on wiring up the electric water heater in the garage, and another tradesperson or even a homeowner seeing a flipped circuit breaker on the exterior panel and turning the power back on to the circuit, shocking the person working on the water heater.

“In-sight” means exactly what it sounds like: the electrical disconnect needs to be directly visible from the water heater itself. That way, if someone were to go to inadvertently turn the electricty back on, they would see that someone is still working on the circuit and hopefully decide not to shock the worker.

 

What Devices Can Be Used as an Electrical Disconnect for a Water Heater?

As of 2023 National Electrical Code, you have four, but really three options:

• A Circuit Breaker at an in-sight Electrical Panel
• An in-sight Pull-Disconnect or Circuit-Breaker Switch box
• A regular wall-switch (similar to a light switch) in-sight of the equipment
• Any of the the previous devices can also be used when they are installed out of sight BUT they must be able to be physically locked out from operation.

 

Can a Plug and Receptacle be Used for an Electric Water Heater?

Not anymore. Once upon a time, this was a configuration that was allowed and commonly used to energize water heaters and satisfied the “in-sight” portion of the code as you could just un-plug the water heater to de-energize it and the cord was never longer than 6-feet. Now, this is no longer the case.

According to the National Electric Code (NEC), water heaters and other fixed appliances must be hard-wired directly to a dedicated circuit and cannot be connected with a cord and plug. The reason for this requirement is that water heaters draw a significant amount of power and can generate a lot of heat. A cord and plug can become a potential fire hazard due to the high amperage and heat generated by the water heater, as well as the risk of damage to the plug or receptacle over time. I know from first hand experience that these older water heater plugs would often be very warm to the touch, a sign of electrical resistance, and the plastic around the brass contacts would often become melted from the excess heat.

A disconnecting means is required at electric water heaters for safety reasons to allow for easy maintenance and repair of the electric water heater without the risk of electrocution.