I run into this from time to time during a home inspection. A water heater that has been installed using a cord and plug.

The issue is that I cannot find for these electric water heaters that any instruction from the manufacture allows it. 

Some of the installation manuals are pretty vague on the electrical installation instruction and will refer back to ANSI and  NFPA70.  But most state it must be on it own circuit with proper over-current protection and disconnecting means. I have not seen where they specify the use of a cord and plug as this method.

So if they all refer to the Electrical Code for the installation lets look at some of the codes that may be applicable.

First is article 110

110.3 Examination, Identification, Installation, and Use of Equipment
(B) Installation and Use.
Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

Here is the electrical installation page from State Water Heaters- No cord and plug referenced

State Water Heater Manual

This is from Rheem- I do not see a cord and plug being specified

Rheem Manual   

Note: GE’s manual is exactly the same

Next is article 400 for flexible cords and cables

400.7 Uses Permitted
(A) Uses.
Flexible cords and cables shall be used only for the following:

(1) Pendants.

(2) Wiring of luminaires.

(3) Connection of portable luminaires, portable and mobile signs, or appliances.

(4) Elevator cables.

(5) Wiring of cranes and hoists.

(6) Connection of utilization equipment to facilitate frequent interchange.

(7) Prevention of the transmission of noise or vibration.

(8) Appliances where the fastening means and mechanical connections are specifically designed to permit ready removal for maintenance and repair, and the appliance is intended or identified for flexible cord connection.

(9) Connection of moving parts.

(10) Where specifically permitted elsewhere in this Code.

(11) Between an existing receptacle outlet and an inlet, where the inlet provides power to an additional single receptacle outlet. The wiring interconnecting the inlet to the single receptacle outlet shall be a Chapter 3 wiring method. The inlet, receptacle outlet, and Chapter 3 wiring method, including the flexible cord and fittings, shall be a listed assembly specific for this application.

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Now lets  look at Article 422 for Appliances

422.13 Storage-Type Water Heaters
A fixed storage-type water heater that has a capacity of 450 L (120 gal) or less shall be considered a continuous load for the purposes of sizing branch circuits.

Informational Note: For branch-circuit rating, see 422.10.

From the Handbook–
Because certain water heaters are a continuous load, the branch-circuit overcurrent device and conductors are required to be sized based on 125 percent of the water heater nameplate rating unless the over-current device and the assembly it is installed in are listed to be used at 100 percent of its continuous current rating.

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422.16 Flexible Cords
(A) General.
Flexible cord shall be permitted (1) for the connection of appliances to facilitate their frequent interchange or to prevent the transmission of noise or vibration or (2) to facilitate the removal or disconnection of appliances that are fastened in place, where the fastening means and mechanical connections are specifically designed to permit ready removal for maintenance or repair and the appliance is intended or identified for flexible cord connection.

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I guess the one way you could use them is if you have special permission but most likely the inspector is going to refer back to the manufacturer’s instructions.

422.22 Other Installation Methods
Appliances employing methods of installation other than covered by this article shall be permitted to be used only by special permission.

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I see a lot of new construction doing inspections and I never see cord and plug installations for electric water heaters.

I would say that since the only time I see a cord and plug installation is post inspections on existing homes, I assume that most electrical inspectors would not allow this type of installation. 

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So lets put the final nail into the coffin as they say. Let’s look at the UL listing for Household water heaters.

UL 174 Standard for Household Electric Storage Tank Water Heaters

Section 12, Electrical Supply Connections – Cord Connection: Incorporated the requirements of
compliance with referenced standards for attachment plugs provided on small capacity storage tanks, and flexible cords and cables as follows:

12.1 Power supply cords

12.1.2 An attachment plug provided on a small capacity storage tank water heater shall be of the grounding type and shall be rated in accordance with Table 12.1 and shall comply with the Standard for Attachment Plugs and Receptacles, UL 498.

12.1.4 Flexible cords and cables shall comply with the Standard for Flexible Cords and Cables, UL 62.


This is from an older UL 174 but I think it still complies-

SMALL CAPACITY STORAGE TANK WATER HEATER —
A water heater marked with a rated capacity within the range of 1 gallon (3.8 L) to 5 gallons (18.9 L).

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If you find any errors or have additional information that would expand on any code, building standards or manufacturer requirements please let me know.

NCW Home Inspections, LLC  is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…  

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