It can be done with a fixed connection and cut by means of a key of very good quality although in reality it would be best with a 20A bipolar switch or a motor guard with adequate protection (I estimate that 2.4 / 4A would be within the range of a small pump) or a bipolar thermal 10A, The engine guard has the advantage of protecting the engine, which you will not achieve with a thermal device, much less with a common switch As I told you in the previous post, I do not agree at all to start and stop the engine through the plug, that in my opinion is not correct, even if the pump comes from the factory with a record of something that I do not finish To believe, it would be nothing unusual for the owner or another person outside the factory to do it (he would speak very badly of the manufacturer) Cheers