I have a 1HP pump (18.6A) that plugs into an outside GFCI outlet with a standard 3 prong plug. there is no hardwired timer - Is there one i can buy to just put inline (plug-timer-plug)? All the ones I see online and Home Depot are only rated for 15A. This is not an area i want to take a chance . Any suggestions / links to a plug in timer that can handle 20A?