Does an electric water heater require a disconnect?

Wednesday, July 11, 2018

When someone is repairing an electric water heater, they need to be assured that the electricity stays off while they are handling wiring and connections that could shock or kill if the circuit were to suddenly become “live.” So the building code addresses this safety issue by providing several choices of solutions that make the means of disconnecting the circuit either within sight or under the exclusive control of the person working on the water heater. 

    Here are the five options:

1) Panel within sight - If the main electric panel or a subpanel that serves the water heater is within sight, a second means of disconnect is not necessary. So a water heater that is in a garage or utility room with a direct sightline to the nearby panel serving it would be acceptable.

4) Pull disconnect or circuit breaker panel within sight - This is the solution we see most often in new construction.

2) Cord and plug within sight - Although we rarely see this option used anymore, you can wire the water heater with a cord to a wall receptacle that is within sight of the water heater. “Pulling the plug” is the most basic kind of disconnect there is. 

3) Wall switch within sight - This is acceptable, but not necessarily the best choice, because eventually someone in the house will use the switch to try to turn on a light in the closet or room. After flipping it back and forth several times, they will decide that the switch doesn’t work, leaving it in the off position. Your next shower will be a cold one unless you label the switch as “WATER HEATER”. If you do choose this option, the switch be 30-amp rated (not a regular light switch). 

5) Lockout device at panel  - This is a metal gizmo that attaches permanently around the circuit breaker for the water heater in the electric panel, and is used when the panel is not within sight of the water heater. It has a hasp with a hole in it that accepts a small padlock, and allows the circuit breaker to literally be locked into the off position. Only a permanently installed lockout device is acceptable. 

    By the way, the first four options that are specified as “within sight” mean “within sight in both directions”: the switch should be visible from the appliance and the appliance visible from the switch. So, if the switch is just around a corner from where the water heater is located, and you can see it when standing at the switch, but the switch itself is not visible when you are at the water heater, it’s no good. The NEC also defines the range of “within sight” is maximum 50 feet away. 

    Prior to the 2017 edition of the National Electric Code, appliances rated at not over 300 volt amps (watts) or not over 1/8 hp motor were required to have a disconnect [NEC 422.31(a)], but it was not clear that it must be within sight if not lockable. The 2017 edition, however, added “where the switch or circuit breaker is within sight from the appliance” to the citation to clarify the intent.

    Also see our blog posts What is required clearance for access and working space in front of an electric water heater? and Does a water heater need a shut-off valve?

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Here’s links to a collection of more blog posts about WATER HEATERS:

Are water heaters required to be raised off the floor? 

Can a Temperature and Pressure Relief (TPR or T&P) valve be mounted to discharge horizontally?

Where are gas water heaters not allowed to be installed?  

Is the minimum size water heater inlet pipe 1/2" or 3/4" according to the building code? 

Can you use a light switch for a water heater disconnect? 

How can I tell if a water heater is HUD-approved for mobile/manufactured homes?

Can you wire a 240-volt water heater with 120 volts? 

What is required clearance for access and working space in front of an electric water heater? 

Why is the water heater older than the house? 

Is it alright to have a shut-off valve on both the hot and cold water pipes at a water heater?  

What is the minimum clearance to doors and windows for an outdoor tankless gas water heater?  

Why should a tankless water heater have an isolator/service valve kit installed?

When was a gas water heater first required to be elevated 18 inches above a garage floor?  

Can the temperature and pressure relief (TPR) valve discharge pipe for a mobile/manufactured home water heater terminate under the home? 

What is the purpose of a thermostatic mixing valve above a water heater? 

Does a tankless gas water heater still work with no electricity during a power outage?  

•  Why do water heaters have a sacrificial anode? 

What is the difference between a manufactured/mobile home water heater and a regular water heater? 

Does a tankless water heater require a pressure relief valve?

When is a water heater drain pan required?

Why is there water in my water heater drain pan?

What does it mean when a water heater Temperature/Pressure Relief (TPR) discharge pipe is "trapped"? 

Can I leave a gas water heater in place when remodeling a garage into a family room or bedroom? 

Where do I find the water heater in a mobile home?

Does a tankless water heater in an attic require a drain pan? 

Does an electric water heater require a disconnect? 

Is a catch pan and drain piping required for a replacement water heater?

What is the difference between a single element and dual element electric water heater? 

What is an FVIR water heater?

What is a heat pump water heater?

What is a dielectric union?

What's that powdery crust on the pipe connections at the water heater? 

What are the most common installation mistakes with water heater replacement?

Why is my water heater making strange (rumbling, gurgling, knocking or banging) noises? 

What can I do to make my water heater last longer?

How can I determine the age of a water heater if the serial number is missing or decoding it is impossible? 

How does a hydronic heating system work?

What is the difference between a regular water heater and a direct vent water heater? 

What is the difference between a regular water heater and a power vent water heater?

What is backdrafting at a gas water heater? 

How do I determine if a water heater is gas or electric?

What does it mean when a gas appliance (water heater, furnace, or range) has been "red tagged"?  

• What's the valve with the flip-up handle on the water heater for?

• Why is an older water heater an insurance problem?

    Visit our ELECTRICAL and WATER HEATERS pages for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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