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Another amp draw question- electrical corded lawn mower

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  • Another amp draw question- electrical corded lawn mower

    We are not very good at electrical stuff and need advise from you experienced folks about it.

    We connected a new 12amp corded lawn mower to a 12 guage 100-foot extension to wall plug in the basement.

    When we try to cut tall grass, the blade of the mower stuck and (we think) it caused the motor to draw a lot of current (at this time point). One of the circuit breaker in the ciruit breaker cabinet tripped. So, we reset is. It tripped a couple more time as we have learned not to cut the tall grass or not pull the trigger of the lawn mower too much.

    So, is there anything like a breaker/item/surge protector I can put in between the extension cord and the wall plug so the circuit breaker will not be tripped in the future.

    In general, it a circuit breaker is being tripped repeatedly, is it bad for the breaker? Would it fail to trip in the future? Would this be a fire hazard?



  • #2
    Re: Another amp draw question- electrical corded lawn mower

    I have seen breakers to what appear to weaken over time, with repeated overloading of them, not all seem to but some seem to, or you just start out with one that is not as strong as another,

    the breaker is doing exactly what it was designed to do, is to disconnect if the rating of it is exceeded for any length of time, see how a breaker works,

    the recommendation I have for you is to take a smaller swath on the mower and thus not load it as heavily, as with a full swath, just like one would do with a gas powered mower, so one would not kill the motor it in taller grass,

    the breaker tripping is not "dangerous" unless there is some in proper wiring, but I would suggest to try to listen to the mower and the load that is on it and cut in such a way that it is not being over loaded, and not tripping the breaker, but I suggest not over loading the breaker if possible,

    I have seen in line GFI units but not familiar with an in line circuit breaker, besides some plug in strips that have a CB in them,

    If you have a 15 amp breaker it would be hard to say which breaker would trip first if you put a 15 amp breaker later in the line, if you have a 20 amp in the box and put a 15 amp down line in the cord some place in theory 15 amp should snap first,
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    • #3
      Re: Another amp draw question- electrical corded lawn mower

      What size breaker?
      Do you need all that 100 foot cord?
      How tall is the grass?
      Any thing else running on this same circuit? Evan a couple lights will draw an amp or two which might be enough to put you over the edge.

      1. As BHD said; take a smaller bite (swath), this will reduce the load on the motor and thereby the amp draw a bit.
      2. Use a circuit with a 20A breaker if available but DON'T replace the 15A with a 20A as the wiring will not be sized correctly and you will end up burning your house down, GET AN ELECTRICIAN TO UPGRADE THE CIRCUIT OR INSTALL A NEW DEDICATED CIRCUIT FOR THE MOWER. [this is probably the best course of action for a long term solution]
      3. If you can get a cord with 10 Gauge wire. Not cheap but will help with the voltage drop. The longer the cord, the greater the voltage drop and the current goes up trying make up for lower voltage. The motor wants x number of watts and its gonna try to get it through some combination of volts/amps.
      4. Mow more often so the grass is shorter and only when the lawn is dry. This will also reduce the amp draw on the motor because the mower blade does not have to push as much weight (tall or wet grass).
      "It's a table saw, do you know where your fingers are?" Bob D. 2006


      1/20/2017 - The Beginning of a new Error


      • #4
        Re: Another amp draw question- electrical corded lawn mower

        You have several issues.

        You are overloading your mower, or using an undersized mower. Sometimes an electric mower is not appropriate...
        But you can get better performance by taking lighter cuts. You should try not to cut more than one-third of the blade in any mowing session. Besides, it can traumatize and damage the lawn.

        Your extension cord is too small. You need a 10g for a 12A mower at 100 feet. This can be contributing to the tripping, and is likely shorteing the life of your mower.

        The receptacle you're using needs to be a GFI protected circuit, you should check to see if you are. It's a personal safety issue.

        Adding an inline breaker (they do have these, and inline GFIs as well) is not the solution. It will have to be smaller than the panelboad breaker in order for it to trip first. Which means it will be tripping more frequently.

        Some breakers are rated for switch duty (marked SWD) and these are heavier duty. But it isn't really possible to answer your question... in general, a breaker has an internal contact that DOES draw an arc every time it trips. Eventually it WILL fail. Other internal parts are subject to failure as well. Breakers and breaker panels come in various quality grades. Cutler-Hamer or Square D QO is good stuff, a Federal Pacific panel was probably a hazard the day it was manufactured. But ANY mechanical device has a finite life. All switches and contactors, including breakers, are subject to failure. The more cycle it sees, the more of its life you will use up. Obviously if your breaker is marked SWD it will last longer than a non-SWD breaker. BUt who knows how many trips it will last? I've never seen specs on this.

        In any case, if you are repeatedly tripping a breaker, it is telling you that you are oveloading it. Why continue to do that? Get a proper mower, use a proper cord, plug into an appropriately sized and protected receptacle, and take appropriately light cuts so that you won't overload your machine or your branch circuit.

        The problem with asking for trouble is that you are likely to find it pretty easily. People that never seem to have problems are not really luckier... they just don't put themselves or their equipment in situations where they are stressed or working in a way that seems unnatural.

        Be careful... be prudent!


        • #5
          Re: Another amp draw question- electrical corded lawn mower

          Thanks for all the replies.

          You guys are truely honest on this that I should cut more often. And there are good points about wire inside the outlet and the trip breaker issue.

          Also, we did not run any AC or light when using the corded lawn mower =)

          I have to admit that we did not think it thru when we bought the corded. Since we triped the breaker a few time 2 week ago, we have not used it. We just use the battery-operated trimmer to trim the grass.

          Yip, the lawn mower has been in "lock-down" since then and I hesitate to use it until I think it thru and got the experience/comments from you folks.

          BTW, is there way to check the amp rating of that particular circuit breaker (in addition to the "SWD") or the "amp rating" of the wire between the outlet and circuit breaker?


          • #6
            Re: Another amp draw question- electrical corded lawn mower

            The breaker should be marked. Often it's right on the end of the trip/reset lever.

            Single conductor wire, should be marked on the insulation. 14g is used for 15A; 12g is used for 20A.

            Romex (trade name for NMB) is marked on the outer jacket. This part may be stripped almost all the way back in your panel or electrical box. If you can't see the marking, turn off the power and measure the wire. You can find the diameter of 14 gauge and 12 gauge easily on the web.

            But, if you are not familiar with working with electrical power... you really should hire an electrician. It's nothing to trifle with.


            • #7
              Re: Another amp draw question- electrical corded lawn mower

              Just buy a 6 hp gasoline lawnmower, and be done with it.