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How can we run smart-ups 3000 rackmount on a 20a circuit?

Discussion in Smart-UPS & Symmetra LX / RM started by Eugene , 7/20/2017 9:24 PM
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  • ewoo
    New Member New Member
    Eugene 7/20/2017 9:24 PM

    I purchased APC Smart-UPS 3000VA LCD RM 2U UPS (SMT3000RM2U), but I only have 20 AMPS circuit.  Is there any adapter that will allow me to operate SMT3000RM2U safely in 20 AMPS circuit?  Thanks

  • wayne_i
    Apprentice Apprentice
    Wayne 7/20/2017 11:54 PM (in response to Eugene)

    Hi Eugene,

    While you can find conversion for a locking ("twist-lock") plug on-line, there are adapters you can buy "locally" that will allow you to convert from a regular (straight blade) 30 amp plug to 15 amp plug.

    BUT before I go further, I ask you to consider what the result will be, and what can be considered "safe".

    A 20 amp circuit is "rated" to provide only 2/3 the current of a 30 amp circuit-- or approximately 2000VA from the UPS, considering efficiency. Theoretically, exceeding 20 amps (or 2000VA load on the UPS) SHOULD cause the circuit breaker to trip, resulting in the 3000VA UPS switching over to battery operation until first the load is reduced AND then someone resets the circuit breaker. Assuming you chose the 3000VA model so that you could approach that load, this is not a practical solution. If you chose the 3000VA model while considering the (community) perspective of running close to 1/2 or 2/3 the max rating of the UPS, you MAY get away with this arrangement.

    Regarding safety, circuit breakers and fuses open quickly under an extreme overload or short circuit, but they WILL tolerate a "modest" overload for a while (could be many minutes) which could lead to heating of the wires and connectors, something that really should NOT be considered "safe". A 3000VA UPS is designed to draw 30 amps indefinitely if that is what the load needs, so there is the potential to create such an overload condition.

    The "punch line"-- this is NOT a recommended solution, but you can search on-line for NEMA L5-30R to L5-20P (or 5-20P if your existing receptacle is "straight-blade, again, not recommended) adapters for converting the factory installed locking connector, or you can buy adapters to go from a 30 amp to 15 amp straight blade plug at most stores that sell RV supplies and accessories.

  • liamg
    =S= Representative
    Liam 7/25/2017 7:32 PM (in response to Eugene)

    I would also like to note that using an adapter or modifying the input plug will void the UL listing of the UPS as well as the Equipment Protection Policy of the UPS. In short, it will work, but it is not supported and is potentially unsafe. APC strongly recommends having the proper circuit installed or using a smaller UPS. 

  • eBrain
    New Member New Member
    Atiq 7/11/2018 6:52 PM (in response to Eugene)

    We have purchased exact same model and have exact same issue except our load is 1300 Watts. We purchased 2 units one attached to storage and other attached to server. Went for 3000 Watts option to have additional power available down the road when we move to new facility in 6 months.

    If I understood correctly unit does not always draw 3000 Watts/30 Amps If we have 1300 watts max load will be 1300 Watts/15 Amps. Can you please confirm or share relationship between load and power consumption? Thanks

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