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  1. #1
    Jerome W. Young's Avatar
    Jerome W. Young Guest

    Default toggle switch used as water heater disconnect

    I see this two or three times a year where someone has wired the water heater to a light switch. The switch is dedicated to the water heater but it seems that this is a problem. Any thoughts on whether this is at all acceptable and why it is not

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  2. #2
    Join Date
    Mar 2009
    Colorado Front Range

    Default Re: toggle switch used as water heater disconnect

    Specifically, a 15 AMP switch can't be used on a 30 AMP rated water heater. It might be acceptable for a smaller one though. The answer to your question is load specific.

    Is the switch actually a light switch, probably rated at 15 AMPs, or is it a heavy duty switch rated for the water heater load? The chances are pretty good you can't tell without removing the cover plate. The heavy duty switch will fill most of the area of the box and a "light switch" won't. Many of the heavy duty switches have ratings posted on the front so you can see them with the cover plate removed. With the cover plate on the look the same.

  3. #3
    Join Date
    Feb 2009
    On The Mason-Dixon Line

    Default Re: toggle switch used as water heater disconnect


    The switch must be rated for the Voltage of the water heater ( 120 , 240 etc) and the amperage drawn by the water heater -2008 NEC 404.14

    If the water heater is 240 volt you must use a 2 pole switch to disconnect all ungrounded conductors - 2008 NEC 404.15(B)

    The switch must be indicating ( must state on / off on it ) as per
    2008 NEC 422.35 and 404.7

    side note:
    Most switches rated 20 amperes , the body of the switch is red. 30 amperes, the body of the switch is green.

  4. #4
    Join Date
    Jul 2008
    Snowbird (this means I'm retired and migrate between locations), FL/MI

    Default Re: toggle switch used as water heater disconnect

    What kind and rating water heater? (electric or gas power vent; storage type (size) or tankless; 120, 120/240 or 240 and rating less than or greater than 13.3A; storage capacity less than 120 gal, insty-hot; dmand type, etc.).

    Does the service have a main disconnect or is it a split bus?

    NEC 422.30 requires that the appliance must have a means of disconnect. This would normally be located in the panel (load center), (lock out cover if not in sight or more than 50 ft), or it could be provided by a aseparte disconnect switch. Although not normally done, 422.34 does allow the unit switch that is an integral part of an appliance having an "OFF" (indicating) postiion that disconnects all ungrounded conductors from the source to be considered the required disconnecting means. In many local codes this is not acceptable. NEC 422.34 further requires that there be another means of disconnect for the appliance, which in the case of a one-family dwelling is USUALLY the main service disconnect.

    NEC 422.35 requires that switches and circuit breakers used as the disconnecting means must be of the indicating type, meaning they must clearly show that they are in the "ON" or "Off" position.

    NEC 422.31(B) requires that for permanently connected appliances rated greater than 300 volt-amperes or 1/8 horsepower, the disconnecting means must be within sight of the appliance, or be capable of being locked in the "OPEN" position. .

    A non-fused AC type pull-out disconnect is usually what I've seen for the standard electric storage type water heater usually used for residences where a second disconnect is required not otherwise provided (split bus or if main plus circuit breaker - not able to be locked out) and located within sight while servicing & w/in 50 ft.

    P.S. I'm dubious about the phrase "light switch" simultaneous disconnection of all ungrounded conductors - not a mushy snap.

    Last edited by H.G. Watson, Sr.; 12-16-2009 at 08:40 AM.

  5. #5
    Join Date
    Mar 2007
    Ormond Beach, Florida

    Default Re: toggle switch used as water heater disconnect

    Whenever I've seen them, and the correctly rated switches are used, it takes a fair amount of effort to switch the switch from 'on' to 'off' and vice versa.

    As H.G. said, it's "not a mushy snap.", there is definitely something to it.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( )

  6. #6
    Jerome W. Young's Avatar
    Jerome W. Young Guest

    Default Re: toggle switch used as water heater disconnect

    thanks to all for your input.


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